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Star tuned magazine june 2004
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STJRTUNED
Information for the Independent Mercedes-Benz Service Professional
June 2004 U.S. $6.00 € 12.50
Group Publisher
FEATURE ARTICLES
Chri stoph er M. Ayers, Jr.
cayers@cmacomm.com
Editor
4MATIC AND ETS
Joe Woods Traction by Pipe and by Wire
jwoods@c macomm.com The last (for now) in our traction control series
MBUSA Technical
Content Advisor
Donald Rotolo
Donald.Rotolo@mbusa.com
Project Director
Andrew Brzo zowsk i
Brzozows ki A@mbusa.com
FUEL PRESSURE AND VOLUME
The simple is not easy
Ar t Director
Jef Sturm
jsturm@cma co mm.com
Production Manager
Joe Cristi ano
jcri stiano@c ma comm.com
TEXTBOOK CASE
Circulation Manager 202 Climate Control, An easy exercise
Phillip A. Helon
phelon@c macomm. co m
List Consu ltant
NFocus
DEPARTMENTS
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7. Four-wheel-dri ve increases traction, often enough The ord in ary, fam iliar diffe rential is an 'open' dif-
to s usta in movement and co ntro l un der cond itions fe re ntia l. Torque deli vered thro ugh the drives haft
that mig ht otherwise mea n the d ri ve r wo ul d choose pinion a nd differe ntial ring gear applies equally
to stop or would get stu ck in s now, mud or sand. through the sp ider gears to each axle halfs haft,
Fo ur-w hee l-drive is n ot co nsta ntly adva ntageou s, rega rdl ess of individu al halfs haft speed. Aside from
however, because it mecha ni ca lly coup les all th e s li ght fri cti on betwee n in te rn al parts, an open dif-
whee ls a nd dr ivetrains togeth er; and so metimes, fe re ntial a pplies equal to rque to each axle - with the
surprisingly e nough, th at conn ec tion ca n work co nseq uence that th e maximum torq ue th e differen-
aga in st optimi zati on of traction a nd co ntro l. There tial can a pply to its drivew hee ls is just double what
have bee n two q uite di ffe rent syste ms called th e d ri vewheel with less tracti on can trans mit alone,
4MATIC, the fi rst hydrauli c, beginning about 199 0 the drivew heel that s lips first. Once that first wheel
and the second electro nic, wo rk ing through th e s pin s, th e vehicle stops progress. This is exactly
service brakes, starting in 1998. We concentrate what we see when a ca r sp in s a drivewh eel in a
he re on the earlier system sin ce yo u're more likely s nowp ile or mudh ole: Until that wheel regain s trac-
to see it in an ind ependent shop. tion, a sta ti onary car does n't budge. In the extremes
of lim ited traction, an open diffe rential gives you
Locked and Open Differentials one-wh ee l-drive, and, worse yet, drive through
wh ichever wheel has less tracti on .
So we move to th e locked or limited-slip differen-
"Four-wheel-drive" can be a mi sleading descrip-
tial. "Locked" is an exagge rati on, as you know,
ti on. In principle, of course, any driveline system
because in side and outside wheels must travel dif-
conducting powe r through the tra nsmiss ion to a ll
fere nt speeds in a turn. Otherwise th e inside wheel,
four wheels is 'four-wheel-drive.' Th ere are, howeve r,
us ually less heavily loaded as centrifugal force
significa nt differences ari sing from the distinction
throws th e weight outward , must skid forward along
between locked and open differentials. Let's have
t he paveme nt.
tha t clear fi rst.
The 4MATIC differenti als ' lock' in a way sim ilar to
the limited-slip diffe re ntia ls yo u may know fro m
do mestic trucks or high-perform ance (at least fast-
accelera ti on) vehi cles. In most of t hose, a co nstantly
s prin g-load ed multi disk clutch lin ks the opposite-
s ide axle s hafts , th rough a friction material and spe-
cia l lubri cant, both requiring peri ocii c replacement.
8. 4MATICAND ETS
The earli er 4MATICs use hyd rauli cs to engage th e This mea ns two wheels, one on each axle, have to
clutches, as we'll see. slip simultaneou sly for the ve hi cle's motion to stop.
There are al so true lock ing differentials using slid- Such four-wheel-drive wi ll , however, represent a sig-
in g-dog clutches, but th ese engage with an imm ed i- nifi cant traction improvement over plain-va n i lI a
ate, heavy clank, a force remin iscent of excavation or two-whee l-d rive. After aU, it means at l east a dou-
railroad eq uipment, an engagement force that would bling of traction, and usuall y more th an that, ass um-
be quite unwelcome in a sedan. With an earthmov- in g so mew hat different traction at each wheel. Ju st
ing impl ement, this doesn't matter sin ce the grind- as two-wh ee l-drive through an open di fferential real-
ing ea rth moves und er th e tire lugs and si nce nei- ly mea ns one-whee l-d rive, four-wheel-d rive through
ther driving comfort nor speed was a priority, any- two open differentials really means two-wheel-drive.
way. With a sedan, that's out of the qu estion . On a That's more traction, but it doesn't use all th e trac-
vehi cle driv ing mostl y on hard pavem ent, you don't tion ava il ab le.
want a truly lockin g differential, not on ly because A four-wheel-drive syste m that locks the front and
that wou ld abrade the tires with lowe r load qui ck ly, rear ax les together still has the problem that one axle
but also because it would mea n one or t he other tire or th e other must slip in every turn, because the front
on an axl e would have to slid e in every turn , actual- wheels will invariab ly follow a track along a sma ll er
ly reducing traction eve n und er what should have radius and shorter path than the rears. A long tim e
been id ea l pavement co nditi ons. ago, I had an anci ent Jeep th at never rea ll y got stuck,
but took every turn with unpredictab le directional
Torque through the Transfer Case excitemen t anytim e four-wheel-drive was engaged.
You co uld never tell whether the front or the rear
ax le wo uld slide loose sideways first - that depended
The earli est four-wheel-drive systems simpl y used
on everything from the load to the quality of th e grav-
a second driveshaft from a transfer case to the front
el on th e road. And your co rrective maneuver had to
ax le differential, where anoth er open dif-
wait until th e slip was clea rly under-
ferential did its torque-
way, because you turned the
splittin g wo rk. The
steering whee l in opposite
sa me 'l ess-trac-
directions to recover
tion' limi tation
depending on which axle
st i II app l ies,
slid. Exciteme nt, as I said.
but with this
The obvi ous manufactur-
advantage: The
in g fix is to in clu de an
average speed
interax le differential, which
of the fron t
all modern fo ur-wheel-drives
wheels WO Uld ,
do. You ca n't just add a center
by so lid
differential and let it go at that,
mechanical
howeve r, or you're back with
Iin l<age, move at
yo ur original prob l em:
exactly th e same
A ll the torque goes to
speed as the
th e first whee l
average speed of
that slips, and the
t he rears ("aver-
ve hi c l e stops
age" because each
there. FOUf-
w h ee l on each
w h ee l-dri ve
ax l e ca n st ill
with three open
move at a differ-
differentials
ent speed from
beco mes, in the
its opposite num-
extreme, one-
ber, but each axle's differen-
wheel-drive again.
tia l ring gear turns at exactly the
same speed as th e other axle's).
The transfer case can engage two-wheel-drive only, four-wheel-drive or four-wheel-locked. In the last case, front and
rear axles turn at the same speed.
9. 4MATIC Progressive Locks sup plementary front drivetrain and the transfer
case, but also a detailed hydraulic system, from
So the Mercedes-Benz 4MATIC system emp loys pump to actuator pistons, to actuate the various dif-
'locked' four-wheel-drive when the various sensors ferentiallocks that come into play under conditions
indicate the need for the add itional traction, but not we'll discuss in a minute. ETS, the new 4MATlC sys-
unde r normal driving conditions when ordinary two- tem emp loying 4ETS, in contrast, works mainly elec-
whee l-drive through the open rear differential is suf- tronically (thus the 'Wire' of our subtitle), with the
ficie nt to conduct all the forward drive moment the control unit activating specific wheel brakes to keep
engine can deliver to the whee ls, and not under the wheel with the least traction from sp inning. ETS
those specia l driving conditions when - paradoxi- works specificall y with two-wheel-drive cars; 4ETS
cally - a locked four-wheel- drive could make a low- applies to those with a front driveax le. Somewhat
tracti on condition worse. confusingly, 4ETS is also called 4MATlC.
Perhaps the most important such contrary condi- Here are the progressive steps 4MATIC
tion occurs during hard-braked, ABS-pu lsed stops, emp loys when the wheelspeed sensors and the
particularly in turns. If foul'-wheel -drive were still steering wheel sensor information point to drive-
engaged under those conditions, it would be possible wheel spin: Driving along an ordinary road with
for the interconnected drivelines either to mask a good traction and no whee ls pin, the car works by
whee l's slip from the sensor's report and thus block ordinary two-wheel-drive with an open differen-
the control unit's recognition and countermeasures, tial at the rear drivewheels. This provides the
or to force a wheel with limited traction to turn at the best combinatio n of drive and directional traction
same speed as the others (this last is most noticeable in the absence of a problem.
during a steep turn or rapid steering changes, The old er hydraulic system provides open-dif-
when whee lspeed varies at the different ferential two-whee l-drive because the multi-
whee ls because each follows a path with disk clutch pack for the center differential lock
a different turning radius and differ- is spring loaded closed, that is,
ent length (and thus, a different engaged. This couples the input
speed ). To accommodate turns, one shaft from the transmission to
of th e inputs to the 4MATIC contro l the transfer case planetary car-
Llnit is a steering whee l angle sen- rier, sp lin ed directly to the dri-
sor, similar but not identical to or veshaft for the rear axle. This is
interchangeable with the one used the fail-safe mode of the system,
with ASR, ESP and ETS. insuring rear-axle two-wheel-
The greater the steering whee l drive regardless of any electri-
angle, the larger the speed difference ca lor hydraulic fault in the
the system allows mechanism.
between the wheels.
4MATIC is the
'most mechanical'
(thus the 'Pipe' of our
subtit l e) of the
Mercedes-Benz trac-
tion contro l systems,
because it involves
not only all the steel
shafts and gear-
works of the
The system works hydraulically, but it's also internally lubricated with oil. If the sea~s on the multidisk clutch pis-
•
tons start to leak, the hydraulic oil can fill the transfer case and begin to run from the lent. The loss of hydraulic
fluid would be obvious long before that.
10. 4MATIC AND ETS
When the sensors indicate the rear drivewheels
are turning faster than the front wheels, at a thresh-
old determined by the control unit as wheelslip, the
system switches over to its first shift stage, 'compen-
sated' four-wheel-drive. 'Compensated' four-wheel-
drive is neither an open differential nor one that's
locked. Instead, the geometry of the transfer case
gears routes 65 percent of the torque to the rear axle
and 35 percent to the front. This allows all four
whee ls to turn at different speeds, but within plau-
sib le constrai nts of how much traction they might
have and how much drive torque they can absorb .
The system se lects this stage by applying hydraulic
pressure to both the clutch packs in the transfer
case, unloading th e spring-loaded center differential
lock and engaging the front axle drive clutch.
The third stage, the second shift stage, locks the
interaxle differential by releasing hydraulic pres-
sure to its clutch (allowing the spring to lock it)
whil e maintaining engagement pressure to the front
ax le clutch. Now we have traction sim ilar to that old
Jeep - it won't get stuck easily, but a steep turn could
be a problem, were it not for the steering angle sen-
sor, which would signal time to return to the previ-
ous shift stage. To prevent engine surge, the system
briefly engages this stage every time, releasing the
center lock shortly thereafter.
The fourth stage, the third shift stage, adds the
lock for the rear differential, preventing those drive-
whee ls from turning at significantly different
speeds. There is no differential lock on the front axle
differential because that could cause a steering
problem. Better that a driver gets temporarily stuck
than temporarily loses steering.
Since the disks don't mechanically lock, there is
sti ll eno ugh difference of speed between the half-
shafts to accommodate the difference of speeds in
ordinary maneuvers and turns. The system 'locks'
with a substantial but not excessive resistance to
turning at different speeds. There is, in fact, a test
yo u perform with a torque wrench to check the fric-
tional force of the hydraulic 'lock.' Specifications
vary by model, largely reflecting the weight of the
car and its consequent traction . Like any test i nvolv-
ing a live drivetrai n on a hoist with the engine run-
ning, th is requires considerable attention to the cor-
rect procedures to prevent an acc ident.
There are three differentials involved in 4MATIC:
the familiar one in the pumpkin case at the center of
the rear axle, a similar one in front sharing a hous-
ing with the oilpan, and a sun-and-planetary design
in the transfer case connecting the front and rear dri-
veshafts. There is no lock ing clutch in the front axl e
•
differential, because locking the steering wheels
together wo uld destabilize the car during turns. The
lock ing clutch in the rear axle differential is essen-
11. sions. The reason for using a Ravineaux gearset is
th at the geometry allows th e sun and ring gears to
turn in the same direction. The relative sizes of the
sun and planetary gears determine the torque split
front to rear when the center lock is disengaged.
Notice this may mean there is still no usable trac-
tion. It is much less likely that traction con ditions
will be so poor that none of the wheels will have suf-
ficient traction to move the car, but th at is possible.
We can all imagine (a nd some of us who live in the
North have expe rienced!) conditions under which
thi s is just what happens - all the wheels spin, but
th e ca r still can't move. Like all the traction-control
systems, 4MATIC is limited to working in the real
world with real-world physical limitations. It works
very well, but not magically.
Working with 4MATIC
tially the same mechanism familiar from ASD, which
we discussed in an earlier issue. Notice each of these Here are some service points when working on a
differentials is necessary for all but the most primi- 4MATIC car. As with any hydrauli c system, air bub-
tive of four-wh eel-drive systems. And the Mercedes- bles and leaks sometimes occur. You ca n often flush
Benz system is far from the most primitive. air through the system by merely toggling th e serv-
The interaxle differential does not look much like a ice va lve for ward to the test position and running the
differen tial, but here's how it works. The transmis- e ngine. This opens the circuits and lets the oil flow.
s ion for a 4MATIC car is the same as for the others, If there is sti ll a ir in the system, you can vent it from
but the tail s haft ends in a ring gear sh ell rather than the caps on the rear differenti al pistons and by loos-
the output shaft and three-lobed driveflange th at enin g the hydra uli c lines at the transfer case until
co uples to the driveshaft through the fl ex ible rubber the oil flows clea r - usually only a few seconds. By
joint (th e 'Gobbo' joint). The inte rn al teeth of that anecdote, th e most co mmon part requ iring replace-
output ring gear shell engage what initi all y appear to me nt is the pump, but this is probably because the
be th e planetary gears on a carri er. Closer inspection, pump is th e high point in the system a nd loses lubri-
however, reveals a second set of planetary idlers driv- cation first if th ere's a leak. Thi s tandem pump
en by the first set, a nd these seco nd gea rs engage the forms a unit with th e power steering system and also
s un gear at the center. provides hydra ulic press ure for a ny vehicle with
This arrangement of sets of pl a netary idlers on th e hydropne umatic suspe nsion.
carri e r is ca lled a "Ravin ea ux gearset," and gri zzled Th e accumulator, a compressed nitrogen chamber
StarTul1ed readers long on th e job may recall that was atop th e hydra uli c control unit, in cludes a diaphragm
the central gearset of the two-speed automati c tran s- to separate gas from oi. If that diaphragm eve ntually
missions long used in domestic autom atic trans mis- Continued on Page 14
12. 4MATICAND ETS
Shift Modes
The earlier, hydraulic 4MATIC works through the axle; and there are three multidisk clutches: two in
transfer case and rear differential, so it is worth- the transfer case and one in the rear axle. Here's
while seeing exactly what happens when the system how they sequentially engage as traction conditions
functions normally. There are three differentials: in require (reflected in the sensor input information):
the rear axle, in the transfer case and in the front
12
Most of the 4MATIC engagement work occurs
in the transfer case, the
gearbox that delivers 11
torque from the transmis-
sion output shaft's ring
gear to the front and
rear differentials.
Initial drive torque is
100 percent to the
rear axle, switching
to 35/65 front/rear
or 50/50 front/rear,
as calculated by the
electronic control
unit from the wheel-
speed and steering-
wheel-angle sensors.
The final shift mode
engages the interaxle
(transfer case) differential
at 50/50 and, as needed,
locks the rear differential.
First Stage
Normally, the 4MATIC car runs
under the same two-wheel-drive
..
as every other
Mercedes-Benz. 100% 100%
Engine output ~
torque through ..........
the transmis-
L1fIr~~~1i~n;;;~~~~;=~;;r"l:~~F~~
sion twists through the
transfer case to the rear-axle
output shaft. The front multi-
disk clutch engages through its
preload springs. The rear multi-
disk clutch (to the front axle drive) remains dis-
engaged. Keep a 4MATIC car on good, dry pave-
ment and don't nail the pedal to the floor, and
this could be the constant shift mode of the sys-
tem for many thousands of miles.
13. 65%
Second Stage
of the gear wheels in the transfer case's Ravineaux
If the wheels peed sensors report a difference gearset. Except for the momentary pause to confirm
between rear drivewheels and fronts beyond a cer- engagement of the rear multidisk clutch before the
tain threshold (a somewhat flexible threshold front releases, all three of the car's differentials are
depending on the steering angle sensor input as well open at this point, and you have drive to both axles.
as the vehicle speed), the first traction-control
measu re is to engage the front axle drive. The sys-
Third Stage
tem does this by engaging the multidisk clutch at If there is a difference in wheelspeed from front
the rear of the transfer case. Once this clutch to back even with the compensated four-wheel-drive
engages securely, the system then immediately dis- engaged, the system locks the center differential.
engages the spring-loaded front transfer-case clutch. The mechanism for doing so is to vent the pressure
A check valve and fixed orifice preclude disengage- at the front multidisk clutch, allowing the spring to
ment of the front should the rear engagement fail - fe-engage it. Once both transfer case multidisk
to insure the vehicle can still drive with at least rear- clutches engage - the rear by pressure applied, the
axle two-wheel-drive under all circumstances, as front by pressure released - both output shafts
well as to prevent engine overs peed. rotate exactly together. As explained, this improves
This shift mode is called "compensated four- traction as long as the vehicle moves in a straight
wheel-drive" because the torque to the wheels falls line, but can be a problem in a turn. However,
into a 35/65 front/rear proportion as a geometric 4MATIC includes the steering wheel sensor, so that
consequence of the relative sizes and configurations problem should not occur.
Fourth Stage modes, the system locks the rear axle to make its
wheels turn at the same speed. This final state of
The front differential is a permanently open dif- the 4MATIC system has both rear wheels turning
ferential because otherwise there might be a prob- exactly together and the front wheels turning an
lem with steering. The rear differential is usually average speed exactly equal to the rears. Only if aU
open, but if there is still a difference in drivewheel these measures are insufficient will the driver have
speed, after aU the corrections of the previous shift to call for help.
14. 4MATICAND ETS
Continued from Page 11
leaks, the accumulator can cease priming hydraulic Traction by Wire
components and can allow the system to make peri-
odic 'water-hammer' clunks as the pump cycles. If ETS and its multi-axle analog, 4ETS, are simpler,
the noise goes away with the service valve in the test electronic variants of ASD and the earlier hydraulic
position, suspect the accumulator. 4MATIC. The simplification comes from the absence
A mechanical problem that may set you to scratch- of the hydraulic distributor-lockup components
ing yo ur head comes if you remove the front drive- involved in ASD and 4MATIC. Don't be misled, how-
shaft. With the rear driveshaft, you can bend it in ever, there is still plenty of hydraulic work afoot -
the middle at the center bearing to shorten it and but through the brake system. Instead of controlling
remove it from the car. But there is no joint in th e wheelslip by locking one or more differentials , ETS
short front drives haft. Instead, you pull back the se lectively actuates the brake on whichever drive-
rubber boot at the front, loosen the locking cap and wheel s lips. Not all ETS cars have four-wheel-drive,
slide back the splined coupling. Pay close attention but those that do employ plain open differentials all
to centering the shaft in th e flexible joints on around, counting the unclutched sun-and-planetary
reassembly, or you cou ld have a running noise that in the ETS transfer case as plain and open.
will be very hard to diagnose. Match-marking the Such traction increase must obviously toggle on
parts with chalk or paint is a reasonable precaution. and off very rapidly, as fa st as the driving conditions
change. This is possible on ly with a digitally con-
tro lled automatic system, one that works directly from
se nsor inputs rath er than just from driver controls.
The driver, after all, has many other tasks to perform.
~Ob Like ASD, this could mean there would still be dri-
vewhee l slip if there were more delivered eng in e
torque than the available traction could employ. In
~®~t
W- 70e
such a case, both drivewhee ls would s lip, not just
th e one; but a driver with a ny level of aware nes s of
70d
driving dynamics shou ld have noticed the problem
and lightened his foot. To encourage development of
th is awa reness , the in strum ent panel includes a
warning lamp that the syste m is at work retaining
traction, and that the driver should accommodate
hi s expectations to the physics of the availab le
wh eelpatch-to-pavement friction.
ETS works in ways quite familiar to people w ho
know ABS, ASR and ESP. Preventing drivewh eel
sp in by app lying the whee lbrake, in fact, could be
ma rg inally more effective than locking a differential,
s ince the system could control all four wheels at dif-
ferent speeds effectively. With the open front differ-
ential, the older, hydraulic 4MATIC cannot do that.
15. OH road, More OHroad and WayOffroadl
Four-wheel-drive for vehicles that mostly remain on paved
roads serves a different purpose fro m four-w heel-dri ve for trac-
tor-lug wilderness explorers. Ju st as with th e other tracti on-con-
tro.1 systems, this on e increases the effective use of th e limited
traction to help maintain optimi zed co ntrol for the driver, eve n
under circum stances of un expectedly slippery surfaces or oth e r
such control risks. Cars dri ving on pavement have diffe rent, but
not less serious need for traction controls. Th ey may not be
called upon to climb ove r a fa ll en log or obstructing bould er, but
they may have to deal with a poth ole, a patch of black ice and a
grave led surface, all within a fraction of a second a nd at differ-
ent whee ls. The dri ve traction enha nce ment is simil a r, but fo r
quite diffe rent purposes.
4MATIC and 4ETS cars a re the su bject of our major feature
this iss ue, but four-wh eel-drive is nothing n ew to Mercedes-Ben z. While thes e cars can drive on unimproved
roads and even briefly on relatively smooth fields, the company build s oth er four-wh eel-drive vehicles more
suited to greater distan ces from th e pavement.
No doubt, you 're famili ar with th e M-class Mercedes-Benz,
Stuttgart's entry into the SUV market. It actually ha ils from
Tuscaloosa, Alabama, but it's still a Benz. We pl an to carry fea-
tures covering the M-class in upcoming issu es of StarTuned.
A bit more rugged and a b it
more suited to offroad travel is
the GeWndewagen. Whil e thi s
is an esta bli shed des ign (th e
bulletp ro of 'Popemobile' h as
bee n around for yea rs ), the
ca rm a ke r has bee n importing
th em to the USA s in ce 2000 so
you should be seein g th em in
yo ur wor kbay.
Fin ally, and most gn arly of
all , is th e Unimog. Proba bly
th e most capa bl e offroad vehi-
cle on wh eels, if you can' t ge t so mewhe re in a Unimog, you s hould probably
recon sid er wh eth e r yo u rea lly want to go th ere. When som ebody with a
Mo nster-Mudder truck gets buri ed in t he mu ck, he h as to find a h elper to
co me with a Unimog. When
so me body with a Unim og gets
mi red, he has to fin d someo ne
who ca n com e help with a
ve hi cle th at cla nks along on
its steel tracks. Th e re are va ri-
ou s s i zes a nd t y p es of
Unim og, fro m abo ut th e size of
a picku p to a match for a qua r-
ry t r uck. 'Mo gs h ave bee n
im po rted in small numbers fo r ma ny years, ofte n used for
heavy con stru ction , railroad sw itch e ngin es, ex pediti on moth-
er vehi cles or, equipped with so me of th e hu ge va riety of spe-
cial-purpose imple me nts (even s norke ls - really!), doing
everything from digging ditch es, plowing s now a nd blasting
ou t rain sewers to cutting weeds a nd pl a ntin g te lep hone po les. [f yo u want to learn more abo ut Unim ogs, let
us know. We would, too!
16. - Welcome to StarTuned, the magazine for independent service technicians
working on Mercedes-Benz vehicles. Mercedes-Benz sponsors StarTuned
and provides the information coming your way in each issue.
_ The worldwide carmaker wants to present what you need to know to diagnose
and repair Mercedes-Benz cars accurately, quickly and the first time. Text, graphic,
on-line and other technical sources combine to make this possible.
_ Feature articles, derived from approved company sources, focus on
being useful and interesting. Our digest of technical information can help you solve
unanticipated problems quickly and expertly. Our list of Mercedes-Benz dealers can
help you find origjnal, Genuine Mercedes-Benz Parts.
_ We want StarTttned to be both helpful and informative, so please let us know just
what kinds of features and other diagnostic services you'd like to see in it.
We'll continue to bring you selected service bulletins from Mercedes-Benz and
articles covering the different systems on these vehicles.
_ Send your suggestions, questions or comments to us at:
StarTuned
One Mercedes Drive
Montvale, New Jersey 07645
Phone: 1 800 225 6262, ext. 2647
e-mail: StarTuned@mbusa.com
19. At Mercedes-Benz, we believe in being faithful. Faithful to getting
you the parts you want, with all the support you need. And faithful
to a partnership that strives to support your business in more and
better ways than anyone else. So you, in turn, can be faithful to
all those who rely on you. Contact your dealer. Unlike any other.
20. FUEL
PRESSURE
AND
VOLUME
It's not always easy to checl< something simple
In days of techno-yore, when ca rburetors mi xed Fuel injection brought many combustion and
the fuel and air for a n engine 's intake, you could emissions advantages, but it did not bring di agnos-
usually check for fuel with a glance at the dash tic simplicity. You still glance at the dash gauge first
gauge followed by a look down the venturi as yo u (and if a functional Benz gauge says th e tank is
cycled the linkage. If yo u saw a squirt from th e empty, it's e mpty), but yo u need more than your
accelerati on-enrichment pump nozzle, th ere was eyes a nd fin gers to check fuel delivery now. If you
fuel; otherwise, th e bowl was empty. Then the ques- don't find the right pressure and volum e, of cou rse,
tion was why. th e question is still why.
The tool s necessary are a fuel pressure gauge a nd
11) Electric fuel pump. suitable adapter fittin gs, a graduated two-liter flask
1 Suction side, 2 Pressure limiter, 3 Roller-ce ll or bea ke r, a switchab le electric jumper (like a rem ote
pump,4 Motor armature, 5 Check valve, starter button) , a clock with a second hand, and (for
6 Pressure side . many mode ls ) a h a nd-actuated vacuum pump a nd
gauge. You also need to know what to do with them,
2 3 4 5 which is our business here. Finally, though we cer-
tainly hope it's perm a nently unnecessary, have a fire
extinguisher within reach. For safety, disable spark
and any other source of flame. Don't smoke or let
anyone else s moke nea rby. There's a lot of heat e ne r-
gy in sprayed gasolin e, a nd it catches fire very easi ly.
That's why we suggest the pushbutton jumper - if
yo u sudde nly jump back, the pump stops.
111e electric fuel pump used for fuel injection is Genera lly, we think of pressure a nd vo lume tests
an electric motor and a meshed lobe or roller as the procedure to check th e fuel pump. That's true,
forced-displacement pump running in and cooled of co urse, but th at' s not all. Those people who think
by the fuel. Wear points include the brushes and working on cars is easy now because 'the computer
commutator at the pressured end of the arma- detects the probl em and tells yo u what to rep lace, '
ture, the bearings at either end, the check valve should cons ide r what yo u can find with pressure
and the pressure relief With enough grit in the and volum e tests, n eith er one of th em from th e com-
fuel, there could even be wear of the lobes or puter. Ten potential problems imm ed iately sprung to
rollers themselves. mind, though pinpoint tests rem ain on the agenda to
determine which. You ca n probably think of more:
21. 12) Operation of roller-cell pump. 6. The fuel sock and pickup. Most problems with
1 Suction side , 2 Rotor disk, 3 Roller, 4 Roll er these co mponents arise after a ta nkful of dubious
race plate , 5 Pressure side . gaso lin e, leaving a coating on the initial filter and
blocking suction to the pump. Sometimes you may
discover problem s resulting from earlier work in th e
tank.
7. The fuel tank. Some cracks or broken welds at
th e top of a fuel tank can go unnoticed since the re's
no visib le leak, but th ey can allow moisture into th e
unprotected stee l interior, producing rust that
abrades th e pump's working surfaces and plugs th e
filter.
As on an oil pump, the armature is slightly eccen- 8. The vaporjevap system. If a car has good pres-
tric to the pump housing centerline, so the rollers sure a nd volum e to begin with but gradually loses
move in and out as the armature turns, forcing both as it travels a hundred miles or so, the fue l
fuel by positive displacement through the fuel fil- deli very probl em may not a ri se from the pump but
ter and through the supply lines to the fuel rail from a plugged vaporjevap system vent. That ca n
and injectors. Wear or scoring on the lobes, produce a vacuum in the tank working against th e
rollers or races allows fuel to bleed back toward pump, e nough of a vacuum sometim es to let the fuel
the low-pressure side. vaporize at the pump intake.
9. The pressure retention valves. The regul ator
a nd the pump contain check valves and pressure
1. The fuel pump. An electri c motor co upl ed with limi ting va lves that can allow pressure loss if the
a roll er pump, the fuel pump lasts a long tim e. But sea l between their mating surfaces becomes pitted
not, us ually, as long as a car. Bea rings, brush es and or a piece of grit lodges in between.
the commutator all wea r; th e check valve may deve l- 10. The electrical circuit. If there is notable
op leak back after tim e. How lon g the pump lasts res ista nce on the power lin e to the pump or on th e
depe nds largely on the quality of fue l, but yo u can ground line returning the current, that resistance
begin to wonder abo ut a pump wh e n a ca r has effectively throttl es the electri c motor down, reduc-
between 100 and 200 K on th e odo-c lock. ing bot h speed and torqu e. It doesn't take much loss
2. The fuel filter. Current fuel filters can contain of electri cal power to drop the pump below mini-
an a mazing amount of dirt and grit before th ey clog mum delivery thresholds.
up, a nd modern fuels are cleaner than eve r. But some Keep in mind the delivery specifications are not
people still manage to collect enough debris into approx imation s and rough guesses. If th e pressure
their tank to block passages . A motori st who regular- doesn't reach the minimum, th e inj ectors may deliv-
ly uses offbrand fuel or drove with th e tank fill er cap er no fuel at all. If the volume isn't enough, the car
open for a time is a good candidate for a new fi lter. will run out of power before the pedal runs out of
3. The fuel pressure regulator. If it spills fu el travel. Be sure the pressure reaches the specified
back through the return lin e before th ere's enough leve l and there is the s pecified amount of fuel in the
pressure, a bad regulator ca n prevent starting or beaker within the tim e limit.
ca use reduced power at every throttl e setting. Like a The ge neral procedure is thi s: Connect the pres-
defective check valve in a pump, a defective pressure sure gauge to the test port following the diagrams for
regulator can dump system pressure right after th e that model; clamp off the return lin e with a suitable,
engine shuts down, requiring a long crank to restart. non-dam aging clamp; route th e line into a suitable
4. The fuel lines. Th e most obviou s loss of pres- graduated container.
slIre a nd volum e comes with a n ac tive leak, but When you compl ete a fuel pressure and volume
th at's rarely hard to diagnose. A more s ubtle and dif- test, make perfectly certain a ll the fuel lines you
fi cult problem comes with an air leak upstream of opened are securely sealed, without the slightest
the pump, drawing in bubbl es to displace fu el and seepage of fuel. As da ngerous as a fue l fire is in a
absorb pressure. shop with knowledgea ble professionals availabl e to
5. The fuel injectors. If you clamp off th e return put it out, it's much more so as a surprise on the
line to eliminate the regulator from question , know road with no equipment or people to extinguish a ny
the pump holds press ure but observe loss of pressure flame.
in the fue l rail beginning with s hutoff, you have good In followin g is sues we'll cover fuel pressure and
reaso n to suspect on e or more injectors of leaking. vo lume tests model by model.
23. There are many similarities from one Mercedes- Lil<e other Mercedes-Benz climate control sys-
Benz climate control system to anoth er, but it ca n tems, the 202's is fully autom atic. The driver sets
be useful to look in detail at one of the more co m- the desired temperature, and the car engages either
mon , as that's one you're more likely to see. The the heater or the air condition er to realize that tem-
Model 202 C-Class was built between 1994 and perature in side the car. Given normal comfort set-
2000 and, by Mercedes-Benz sta ndard s, in relative- tings, this mea ns the air co ndition er starts as soon
ly large numbers. as the engine is runnin g smoothly or the heater
Ne ither the car nor the climate control system is begins blowing warm air as soon as the engine
the most complex of the co mpany's products. The coolant temperature ris es to a range at which it can
202 HVAC, howeve r, ca n keep its owners as comfort- co ntribute so mething. If you're familiar with how
ab le as almost any automoti ve heating an d cooling automatic climate controls worked in older veh icles,
system. About the only climate-system luxury it like the 190, th e 124 or the 126, there aren 't many
lacks is a separate temperature selector for eac h surpri ses waiting for yo u in the 202.
~on~s eatpasse n ge~ Thi s tim e of year, air co nditioning is likely to be
more on yo ur mind than heating or defrosting, but
th e system is not so distinct. Defrost, for instance,
toggles both 11eat and the air co nditioning on, to
in sure th e dri est and hottest air possible blown
across the windshield. The system will do this
rega rdl ess of climate co ntrol setting when the
defrost button is push ed. This arrange ment is not
uniqu e to th e 202, nor is it for that matter to
Mercedes-Benz. Given that safety considerations
come first, the defrost mode must use every possible
meas ure to dry and clear th e windshield. Both air
co nditionin g and hea t are humidity-redu cing
24. TEXTBOOK CASE
fun ctions, the first by condensing moisture out Clearing the Air
and th e second by raisin g th e ca pac ity of th e air
to abso rb moisture in solution. Thu s both com e on Almost the fi rst element of the climate co ntrol sys-
simultaneously. tem th e incoming air encounters, wheth er the sys-
tem is heating or air conditioning, is th e dust filter.
This is a relatively new component in ca rs (not just
in the 202) and one that many car own ers are not
aware of in th e car. Not being aware of it, they also
are often not aware th at it requires periodi c replace-
ment, like any filter. There is no set in terval since
th ere is no set amount of du st and poll en a driver
will drive through, but checkin g at least once a year
is a reasonabl e precaution , more often wh ere there's
lots of airborne materi al. At th e beginning of air con-
ditioning season is a good opportunity, since the
hea t and humidity of summ er are th e conditions
most likely to encourage growth of any mold on the
element. A suffi ciently clogged du st filter, naturally,
co uld restri ct th e ventilati on quantity in a noti ceable
way, eve n without any adverse odor.
3
2
The filter comes out through the passenger side footwell. Remove the access panel and pull out the old one. This
cabin filter does not use an evacuated bead to seal the edges of the fittel; as was true on some other models. That
means it's easy to remove and replace. Some cars have a charcoal-element filte/~ some do not. The two types are not
interchangeable.
24
25. Just 'upwind' of the filter is the hood inlet drawing
venti lation air in. One aspect of this requiring occa-
sional in spection is the water separator and drain
system ju st below the windshield wipers. Ordinarily,
water and relatively small grit will just wash down
through the trough and pipe to the pavement, but if
there are many leaves, insect parts or other such
debris in the air locally, it is possible to clog the
drain and all ow water to remain. This could possibly
allow moisture into the venti lation intake.
~. ~~~~~~
-:::::::---------
-
... - r::-,--::;"---
26. TEXTBOOK CASE
A9
It's fairly easy to remove the lower panel
under the passenger-side instrument panel and
replace the heater blower. Be careful doing this,
however. In particular, don't replace the blower
merely because there is audible noise coming
from it. Possibly the bearings have worn out
after many years' service, but these are very
long-Jived components - it's more likely the
blower has gotten louder because of debris
reducing airflow, just as a vacuum cleaner gets
louder if you cap off the hose with the palm of
your hand. A slight piece of debris in the squir-
rel cage could also produce noise by unbalanc-
in g the cylindrica l fan and introducing a slight
wobb le. By the way, don't 'test' the blower by
jumpering it with a straigh t 12 volts; the system
..... never uses that much to run the blower. It usu-
ally runs between 4 and 6 volts, with system
-- Me
--!!!
voltage reduced through the series-resistor
block.
The air conditioning compressor includes an
rpm sensor to enab le the MAS control unit to
toggle the compressor off should the drive belt
slip, as indicated by a change in the ratio of com-
pressor to crankshaft speed. Because the system
makes very efficient use of the modest amount
of refrigerant, it is critical to measure the
amount of oi l in the system precisely jf the com-
pressor is replaced. Neither an excess nor a
shortage of air cond itioning oil is compatible
with proper functioning of the climate-control
810/1 system.
Sometimes problems with the entire climate
contro l system arise from the simplest of causes.
Like most Mercedes-Benz heating and coo lin g
systems, the mechanism in the 202 employs a
cabi n temperature sensor in the overhead com-
partment. A very sma ll fan draws air through
Continued on Page 28
27. Testing and Design
Perhaps some engi neers
and designers chose their
work so they could travel to
exotic and beautiful locations
and enjoy the weather. That's
probably not true of climate
control gurus, though. They
must test their prototypes in
places that will challenge the
capacity of the heat exchang-
ers to shift enough BTUs,
whether into or out of the car.
If they go to Houston, it's in
August, to see whether their
new, low-profile AI C con-
denser can cope with 130
degrees in the shade. If they
go to Bemidji, Minnesota, it's
in January, to see how long it
takes to clear a windshield of
the Arctic hoarfrost.
Often, of course, they don't
go anywhere special. Instead,
they build a little cube of
Greenland or the Sahara at
the plant near Stuttgart,
using insulated chambers
and overwhelming heating or
refrigeration equipment.
Is it overdone? Of course. If
it weren't, there would be no
way to insure the climate
control systems could work
in ordinary conditions. After
all, ordinary conditions are
not always so ordinary. Any
idea how hot it can get in
stalled traffic on the Cross-
Bronx Expressway on the
Fourth of July? Or how cold
when the Alberta Clipper
swoops through Minneapolis
in February?
And this is not just for pas-
senger comfort. Absent a
driver who can pay attention
to what he or she is doing
with the wheel and the ped-
als, you can't have automotive
safety. A climate control sys-
tem can and does save lives.
28. TEXTBOOK CASE
Continued from Page 26
th e louvers at that sensor anytime th e ca r is run- Second, it' s almost always a good practice to
nin g. The test for that fan is amaz ingly low-tech: take replace th e rece iver/ drier w hen you open the refrig-
a sma ll shred of paper and hold it against th e lou- erant side, just to be safe. Besides its function as a
ve rs while the engin e runs. If th e fan is working, the moisture abso rb er, the receiver/drier is also a filter
paper w ill stay against the grate. If not, the paper th at can catch most bits of debri s that may work
will fall away. loose in th e syste m. Oth erwis e, th ey could just cycle
Anyti me you open up the refri ge rant sid e of th e through th e co mpressor, expa nsion valve and heat
air cond itioning system, there are two preca uti ons exchangers over and over until they found the most
to obse rve. Oil for th e system, like air conditi oning in co nve ni ent and expe nsive place to lodge.
oils for previous refrigerants, is hygroscop ic, so it Fin aUy, it so metimes happens th at the windows
wi ll draw moisture from the air, even from air that fog and stay partly fogged, even when you push th e
seems entirely dry to you in th e shop. Once in th e defro ster button. Th e first pl ace to check with such a
refrigerant passages, of course, th at could qui ckl y probl em (after yo u're sure th ere's no sodden mass of
produce rust, and there's hardl y a worse place for wet leaves at th e base of the wind shi eld) is the
rust in the car. Be sure to cap any ope n pipe sec ure- sw itchover va lve and linkage working the
ly right away, or flu sh the system if it remains open fres h/rec irculate door, all of it in the same passen-
for any length of time . When in doubt, evac uate th e ger-side area wher e the blower motor resides . There
system again . is a small hook working the door that may have bro-
ken or may have disengaged from the vacu um motor.
N65
Keeping Cool, Keeping Warm
The now-d isco ntinu ed Mode l 202 Benz can
nonetheless keep its driver and passengers at a reasonable
temperature in the passenger compartment, regardless of
the outside climate. Follow standard diagnostic and mainte-
nance techniques, and you can keep your customers happy
and their cars cornfoltable.
Whenever yo u find th e temperature co ntrol sys-
tem doin g so methin g unfamili ar, it' s worth your
whil e to rev iew what th e system is supposed to do
with the controls in a given position . Don 't be
embarrassed to look in th e owner's manual to deter-
min e that. That littl e book let ca n be a surpri sin g
source of good diagnosti c inform ati on.
29. _ Th ese suggestions and solu- meas ure to confirm th at it i s close
tions for technical problems enough to th e teeth to generate th e
come from service bulletins signal (check th e speci fication s for
and other technical informa- th e ca r to confirm the minimum
tion published by Mercedes- altern atin g voltage
Benz, selected and rewritten
for independent repair shops. Cleaning the Cleaners
Sparked, Unsparked
and C lanked of th e crank shaft se nso r. There
All Models with Engines cou Id be oth er sorts of probl ems.
102 or 103 Tf you find an altern ating cur-
rent signal, but th ere is still a
Th er e's not mu ch you hea r in a startin g or runnin g probl em, check
ca r more alarmin g than a knockin g th e signal not onl y with a volt-
metallic sound coming from the meter but with an osc ill oscope.
engin e compartm ent. Sometim es, Som e se nsors should have pul ses
happil y, the cau se is not mech ani- of sequenti ally vari abl e amplitude
ca l within th e engine but som e- wh en th e fl ywh ee l in clud es seg-
thing else. Check with your stetho- ments and mag nets. On ca rs
sco pe and pay attention to the hi gh wh ere th e se nsor follows th e fly-
voltages, but on e more thing to wheel teeth directl y, th e si gnal
check is th e ignition coil itself. If should be even.
th e iron core in a coil com es loose
intern ally, the electrom agneti c
pul ses in th e windings ca n bang
L5
th e core to and fro rapidly, cau sin g You don't have to replace every
thi s suspi ciou s noi se. Coils known filter anytim e you di scover du st on
to have this problem have produ c- it. Certain air filter s, like th e
ti on codes between FD 845 and cycloni c version or the stee l-m es h
847. Ther e could be others. backed flat filter, allow remova l of
large amounts of dirt by com-
Crankshaft Position Sensors pressed air. In areas with ver y
large amounts of airborne du st, it
is frequ entl y good practice to clean
out th e filter hou sing and the sur-
face of th e filter itself periodical1y
, , before you repl ace th e filter ele-
ment itself. Many air filters actu al-
ly beco me more effecti ve with use,
as parti cles fill th e lar ge r
If th e crankshaft positi on se nso r mi crop assages. Eventu all y, of
doesn't work, the engin e won 't course, all filters will present
sta rt. If it fail s whil e th e engin e is enough obstru ction to airfl ow to
runnin g, it stops imm edi ately. A Wh en repl ac in g th e se nsor, impede th e engine's breathing,
loss of crankshaft position signal,
however, does not mean a failure
make sure it does not contac t any
part of th e flywh ee l, but also
-
and th en it is tim e to r eplace them.
30. CABIN FILTERS
We don't always think of the quality of the air as Besides what the cabin filter does for the dri ver
part of a climate contro l system, but one of the most and passengers in terms of the comfort level fro m
importa nt improvements in the internal atmosphere a cleaner air to breathe, it also has a safety fu nc-
of vehicles in recent years comes from the dust fil- tion. Most people are relatively careful about keep-
ters that clean the air passed through the heating, ing the outside of the windshield clean, so they can
a ir-co nditioning and ventilation system. The most see what is coming down the road. It's much less
obvious benefits are a reduction in road dust in the common, however, for car owners to clean the
passe nger compartment, making life more comfort- inside of the windshield. Besides being less con-
able for almost everyone, but particularly for those venient to clean, the buildup of dust and grime is
who have allergies or who drive in very dusty places. much more gradual, so there isn't the kind of per-
The filters do more than that, however. You've ception of the vision-obstructing layer there is from
probably tried to clean air conditioner evaporators road spray or bugs.
and heater cores by spraying various chemicals The cabin filter can't eliminate that problem, but
through the ductwork If there is much growth of it can reduce it substantially. The amount of dust
mold at all, it's a pretty thankless task, unlikely to and small particulates that used to collect on the
work for long. With a dust filter, however, it is possi- inside of the windshield is much lower, so the need
-
ble to prevent that problem from arising at all. If the to clean the glass from the inside is proportionately
mold spores stop on the accord ion-fo ld paper, you reduced.
can remove them with the old insert.
31. Alabama Belmont Oakland Van Nuys
Autobahn Motors Mercedes-Benz of Oakland Keyes Europea n
650-637-2333 510-832-6030 818-461 -3900
Dothan
Mike Schm itz Automotive Beverly Hills Palm Springs Walnut Creek
334-794-6716 Beverly Hills Mercedes-Benz of Palm Springs Stead Molors of Walnut Creek
310-659-2980 760-328-6525 925-937-1655
Hoover
Crown Automobile Buena Park Palo Alto West Covina
205-985-4200 1
·louse of Imports Park Ave nue Motors Penske Motorcars
714-562-11 00 650-494-0311 626-859-1200
Huntsville
Regal Auto Plaza Calabasas Pasadena
Calabasas Motorca rs Colorado
256-837-5752 Rusnak Pasadena
818-59 1-2377 626-792-0226
Colorado Springs
Mobile Carlsbad Mercedes-Benz of Colorado Springs
McConn ell Automotive Pleasanton
Hoehn Motors Me rcedes-Benz of Pleasanton 719-575-7950
251-472-3187 760-438-4454 925-463-2525
Denver
Montgomery Chico MUITay Motor Imports
jack Ingram Motors Courtesy Motors Auto Ce nter Riverside
Walter's 303-759-3400
334-277-5700 530-893-1300
909-688-3332
Claremont Littleton
Tuscaloosa Rocklin Mercedes-Benz of Littleton
Leigh Auto moti ve Penske Motorcars
909-568-2600 Von Housen Motors 303-738-7700
205-556-11 11 916-924-8000
El Dorado Hills Connecticut
Alaska Sacramento
Me rcedes-Benz of Eldorado Hills Mercedes-Benz of Sac ramento
Anchorage 916-567-5100 Danbury
96-92 4-8000 Mercedes-Benz of Danbury
Mercedes-B of An chorage
enz Encino
907-277-3383 San Diego 203-778-6333
Auto Stiegler
818-788-0234 M ercedes-Benz 01' San Diego
Fairbanks 050-279-7202 Fairfield
Cook 's Import Mercedes-Benz of Fa irfi eld
Escondido 203-360-6725
907-459-7070 Mercedes-Benz of Escondido San Francisco
760-745-5000 M ercedes-Benz of San Francisco
Arizona 415-673-2000 Greenwich
Fremont Mercedes-Benz of Greenwich
Chandler Claridge's San Jose 203-869-2050
Mercedes-B of Chandler
enz 510-623-1111 Beshoff
480-403-3444 408-239-2300 Hartford
Fresno New Cou ntry Motor Cars
Phoenix San Jose 866-346-2369
Phoenix Motor Mercedes-Benz of Fresno
559-438-0300 Smy the Europea n
602-264-47 91 408-903-5200 New London
ScottJ;dale Glendale Carriage House of New London
Ca lstar Motors San Luis Obispo 860-447-3361
Schumacher European Kimball Motor
480-99 1-11 55 818-246-1800
005-543-5752 North Haven
Tucson Laguna Niguel Mercedes-Benz of North Haven
Mercedes-Be nz of Laguna Niguel San Rafael
Mercedes-B of Tucso n
enz HAB. Motors 203-239-1313
520-886-131 949-347-3700
415-454-0582
Delaware
Arkansas La Jolla Santa Barbara
Hein z Gietz Autohaus Sa nta Barbara Auto Group Milford
Fayetteville 858-454-7137 805-682-2000 I.G. Burton
jones Motorcars 302-424-3042
Long Beach Santa Monica
479-521 -72 81 Mercedes-Benz of Long Beach
562-988-8300
w. 1. Simonson Wilmington
Little Rock 310-829-45 11 Mercedes-Benz of Wilmington
Riverside Motors Los Angeles 800-800-1949
501-666-9457 Santa Rosa
Downtown L.A. Motors Smothers Europea n
213-748-895 1 Florida
California 707-542-480
Anaheim Modesto Stockton Clearwater
Ca li be r Motors Modesto European Berberian European Motors Lokey Motor
714-777-1900 209-522-8100 209-944-55 11 727-530-1661
Arcadia Monterey Thousand Oaks Coral Gables
Rusnak/Arcadia Mercedes-Benzof Monterey Silve r Star A.G. Bill Ussery Motors
626-447-111 7 83 1-375-2456 805-37 1-5400 305-445-8593
Bakersfield Newport Beach Torrance Daytona Beach
Mercedes-Benz of Bakersfield Fletcher jones Motor Cars Mercedes-Benz of South Bay Mercedes-Benz of Daytona Beach
661-836-3737 949-718-3000 30-303-3500 386-274-4775
32. Ft. Lauderdale Augusta Northbrook Loulsiana
Mercedes-B of Fort Lauderdale
enz Hadel' Autohaus on Edens
954-462-438 1 706-860-1111 847-272-7900 Alexandria
Wa lker Automotive
Ft. Pierce Columbus Orland Park 318-445-6421
Coggin Motor Mall Columbu s Moto r Mercedes-Benz of Orland Park
77 2-466-7000 706-327-3636 708-460-0400 Baton Rouge
Ft. Walton Beach Merceeles-Benz of Baton Rouge
Deluth Pekin 225-490-3101
Quality Imports Atl anta Classic Sud 's
850-863-216 1 770-279-3600 309-347-3191 Lafayette
Gainesville Moss Motors
Kra ft Motorcar Macon Peru 337-235-9086
352-332-7571 Jackson Automotive 1.1'. Chevrolet GEO Nissa n
478-477-4858 815-223-7000 Metairte
Jacksonville Be nson Motor
Brumos Motor Ca rs Savannah Springfield 504-456-3727
904-724-1080 Critz Isringhausen Imports
912-354-7000 217-528-2277 Shreveport
Lakeland Holmes Europea n Motors
Central Florida Eurocars Westmont 318-212-1212
863-688-811 1
Hawaii Laurel Motol·s
Honolulu 630-654-8100 Maine
Maitland
Mercedes-B of Orlando
enz Mercedes-B of Honolulu
enz Indiana Bangor
407-645-4222 808-592-5600 Qu irk Auto Park of Bangor
Evansville 207-941-1 017
Melbourne Idaho D-Patrick
Co nti nenta l Motorca rs 812-473-650 0 Falmouth
321-956-0600 Performance Motors
Boise
Miami L Pearson
yle Fort Wayne 207-781-3207
208-377-3900 Shaver Im po rts
Mercedes-B of Miami
enz 260-432-7200
305-919-8000 Maryland
Pocatello
Naples Robert Allen Highland Annapolis
Me rcedes-B of N
enz aples 208-232-1062 Terry Shaver Imports Mercedes-Benz of Annapolis
239-643-5006 219-924-2400 410-268-2222
Illinois Indianapolis
Orlando Bethesda
Mercedes-B of South Orlando
enz World Wiel e Moto rs Euro Motorca rs
407-367-2700 Arlington Heights 3 17-580-68 10 30 1-986-8800
Mercedes-Benz of Arlington Heights
Pensacola 847-259-4455 Lafayette Cockeysville
Centennial Imports Mike Raisor Imports Va ll ey Motors
85 0-432-9903 Barrington 765-448-4582 410-666-7777
Motor Werks of Barrington
Pompano Beach 847-38 1-8900 Mishawaka Hagerstown
Autohau s Pompa no Gurley-L Motorwerl(s
eep Mercedes-Benz of Hagerstown
954-943-5000 Bourbonnais 219-256-1500 301-733-2301
Napleton's Autowerks
Sarasota 815-933-822 1 Iowa Owings Mills
AN Lu xury Imports H& H Motor Cars
941-923-3441 Champaign Davenport 410-363-3900
Sulli va n-Parkhi ll Imports Luj ack's Northpark
St. Petersburg 217-352-4161 563-388-8610 Salisbury
Crown Eurocars Pohanka TM
727-52 6-3738 Chicago Des Moines 410-548-34 11
Mercedes-Benz of Chi cago Mercedes-B of Des Moin es
enz
Tallahassee 312-944-0500 515-334-8339 Silver Spring
Capital Eu rocars Herb Gordon
850-574-3777 DeKaib Iowa City 301-890-3030
Brian Bemis Imports CiJ ezik-Sayer Imports
Tampa 815-758-545 1 319-337-6100
M erced es-B of Tam pa
enz Massachusetts
81 3-870-0010 Hoffman Estates
Mercedes-Benz of Hoffm an Estates Boston
847-885-7000 Westwood
West Palm Beach Shawnee Mission 78 1-688-1000
Mercedes-B of Palm Beach
enz Aristocrat Motors
561-689-6363 Lake Bluff 913-677-3300 Boyston
Knauz Continental Autos Wagner
Georgia 847-234-1700 Wichita 508-869-6766
Scholfi eld Auto Plaza
Albany Lincolnwood 316-688-5000 Haverhill
Hentschel Motorcars Loeber Motors Smith Moto r
912-883-2040 847-675-1000 978-372-2552
Kentucky
Athens Loves Park Ashland Hyannis
Mercedes-B of Athens
enz Napleton 's Autowe rks Sim Fryson Motor Trans-Atla ntic Motors
706-549-6600 815- 636-6600 508-775-4526
606-329-2288
Atlanta Marion Bowling Green Lynnfield
Mercedes-B of South Atlanta
enz Foley-Sweit ze r Bowling Green Imports Flagship Moto rcars
770-964-1600 618-997-1313 270-745-0001 78 1-596-9700
Atlanta Naperville Lexington Natick
RBM of Atla nta Mercedes-Benz of Naperville James Motor Foreign Nt otors West
770-390-0700 630-305-4560 859-268-11 50 508-655-5350
Atlanta Normal Loulsville Somerville
Mercedes-Benz of Buckhead Sud 's Motor Car T Motors
afel Chambers Motorcars of Boston
404-846-3500 309-454-1101 502-896-4411 617-666-4100
