Doosan mt40 b articulated dump truck service repair manual

1.1.1STRUCTURE & FUNCTION
SHOP MANUAL MT40B - 06.99
Chapter 1 Engine
Main Index
Chapter 1.1 Structure Function ..............................................................3
Chapter 12 Testing & Adjusting..............................................................33
Chapter 1.3 Disassembly & Assembly...................................................57
Chapter 1.5 Trouble shooting..................................................................163

Engine
1.1 Structure & Function
Index
Cylinder block ........................................................................................4
Cylinder liner ............................................................................................................................... 4
Pistons ....................................................................................................6
Piston rings ................................................................................................................................. 7
Connecting rods ....................................................................................8
Gear drive ..................................................................................................................................12
Belt drive ...................................................................................................................................13
Oil pump ....................................................................................................................................14
Oil cleaner..................................................................................................................................15
Oil cooler ...................................................................................................................................16
Lubrication oilways .....................................................................................................................16
Turbo filter ..................................................................................................................................17
Cooling system ..........................................................................................................................20
Circulation ..................................................................................................................................21
Charge air cooler ........................................................................................................................21
Thermostat and thermostat housing ...........................................................................................22
Coolant pump .............................................................................................................................23
Scania Digital Engine Control system (DEC2) ................................ 24
General ......................................................................................................................................24
Basic features ............................................................................................................................24
Emissions ..................................................................................................................................24
Engine protection .......................................................................................................................24
Important information: ................................................................................................................24
Diagnostics ................................................................................................................................25
Fault finding ...............................................................................................................................25
Control unit .......................................................................................... 26
LED functions during normal operation ......................................... 27
CONTROL STATUS ....................................................................................................................27
SHUTDOWN ..............................................................................................................................27
STARTING .................................................................................................................................27
RUNNING ...................................................................................................................................27
TORQUE LIMIT..........................................................................................................................27
BOOST LIMIT ............................................................................................................................27
POWER- ....................................................................................................................................27
POWER+ ...................................................................................................................................27
Sensors ................................................................................................ 28
Note! ..........................................................................................................................................28
Engine speed .............................................................................................................................28
Charge air temperature ...............................................................................................................28
Charge air pressure ....................................................................................................................28
Coolant temperature ...................................................................................................................28
Oil pressure ...............................................................................................................................28
Junction box ..............................................................................................................................28
Sensor location ................................................................................... 29
Electronically controlled actuator................................................................................................30
Control rack sensor ....................................................................................................................30
Fuel shut-off valve .....................................................................................................................31
Throttle position sensor ..............................................................................................................31

STRUCTURE & FUNCTION1.1.4
Cylinder block
1. Cylinder liner
2. Cylinder block
3. Cylinder head gasket
4. Shim
Cylinder liner
The cylinder liners are of “wet” type, i.e. they are surrounded by coolant.
At the top of the cylinder liners is a loose scraper ring which removes residual carbon from the edge of the
piston crown and reduces the risk of cylinder liner wear.
The cylinder liners and scraper rings are replaceable.
To ensure a good seal, the edge of the cylinder liner stands 0.3 mm proud of the surface of the cylinder block.
As a result, the cylinder head gasket is pressed against the cylinder head. The cylinder liner is adjusted to the
correct height by means of a shim.
The cylinder block is a one-piece casting with 8 cylinders arranged in two rows at 90° to each other in a Vee
configuration. There is a separate cylinder head for each cylinder.
A steel gasket seals between cylinder block and cylinder head. Seals are bonded in place at the oil and coolant
passages.

The inside of the cylinder liner is machined by what is known as plateau honing. This type of machining leaves
a fine pattern of grooves which ensure that the oil needed for lubrication between piston rings and liner remains
on the wall of the liner. The design of the pattern is of major importance for ensuring low oil consumption in the
engine.
The lower part of the cylinder liner is to some extent movable to allow for thermal expansion.
Three sealing rings, 1 - 3, seal the lower part of the liner at different levels. An overflow hole which discharges
in the side of the cylinder block is provided between the two bottom rings.
Leakage in any of the sealing rings will result in oil or coolant coming out of the overflow hole.
The V configuration of the cylinders means that the main bearings are also exposed to lateral stress. For this
reason, the main bearing caps are attached with both vertical and horizontal bolts.
1. Seal for coolant
2. Seal for coolant
3. Seal for oil
4. Overflow hole

Pistons
The pistons are made of high-strength aluminium alloy characterized by low weight and good thermal
dissipation.
For the piston to resist the high pressure and high temperature prevailing in the combustion chamber, the
material is thicker at the piston crown and piston ring grooves than in the remainder of the piston.

Piston rings
For the piston to travel freely, a gap is required between the
piston and cylinder liner.
The piston therefore has two compression rings which seal this
gap and conduct the heat from the piston.
The upper of these rings is exposed to higher pressure than the
intermediate ring and is therefore wedge-shaped, a “keystone”
ring, which increases the force pressing it against the cylinder
wall.
Since the greatest stress is on the upper piston ring groove,
and also to reduce wear, a reinforcement of cast iron is
incorporated in the piston.
The bottom piston ring, the oil scraper ring, prevents oil from
the crankcase from finding its way up to the combustion
chamber.
In the oil scraper ring is a coil spring which presses it against
the cylinder wall.
The design of the piston and piston rings is important for the
engine’s reliability and lubrication as well as for oil and fuel
consumption.
The bowl-shaped combustion chamber in the piston crown has
a protuberance in the centre. The design of this protuberance
ensures that the fuel injected at the end of the compression
stroke is quickly mixed with the air in the combustion chamber.

Connecting rods
The connecting rod and big-end cap consist of a single casting
which is split during the machining operation.
To prevent the big-end cap from being displaced in relation to
the connecting rod, the contact surfaces are provided with
grooves and guide pins. The surfaces are machined together to
ensure a precise and accurate fit. The parts are also marked so
that they can always be fitted in the same position.
The connecting rod and big-end cap are split obliquely, partly
so that the con rod bolts will not be subjected to excessive
loads and partly to enable the piston and con rod to be
withdrawn through the cylinder.
The upper part of the connecting rod is wedge shaped. This
allows a larger journal surface on the underside of the gudgeon
pin where load is greatest during combustion.

Crankshaft
Each compression stroke ”brakes” the crankshaft and each
combustion stroke attempts to increase the speed of rotation of
the crankshaft.
The pistons and connecting rods change their direction of travel
twice during each rotation of the crankshaft. This exposes the
crankshaft to numerous power pulses during each revolution.
The material is of major importance for the useful life of the
crankshaft. Its design and surface treatment also help to extend
its life - for instance, the surface quality of the shaft journals is
an important factor in providing protection against fatigue
failure.
The bearing surfaces on the crankshaft are hardened to a
depth which allows them to be ground several times.
Only the bearing surfaces are hardened as it is important to
retain the toughness of the material in other parts.
The bearing shells of the main and big-end bearings consist of
three layers. An outer layer or backing of steel, an interlayer of
lead-bronze and nearest the crankshaft an overlay consisting of
a mixture of lead and indium or lead, tin and copper. The
innermost layer is usually worn away during the course of
engine utilization.
Thrust washers are used for endways location of the crankshaft
at the rear main bearing. These thrust washers are available in
different thicknesses so that the crankshaft can be adjusted to
the correct clearance. The thrust washers have the same types
of layer as the big-end bearing shells.

Crankshaft damper
The power impulses from the connecting rods give rise to torsional oscillation in the crankshaft. These
oscillations are severest at a certain rpm which varies with the design of the engine, how it is loaded, etc.
Torsional oscillation is characterised as follows:
The flywheel (at the “rear of the crankshaft) rotates with even speed throughout the revolution. When
compared with the flywheel, the front end of the crankshaft will increase and decrease speed of rotation
several times during each revolution.
This oscillation may give rise to noise from the timing gears and increases the risk of crankshaft breakage.
To reduce the oscillation a crankshaft damper is attached to the front end of the crankshaft.
A ring of steel is incorporated in the circular and completely enclosed housing of the crankshaft damper. The
housing is bolted onto the crankshaft.
There is a heavy oil between the housing and ring which damps the relative movement between the two. The
oscillation at the front of the crankshaft is damped by the ring striving to rotate with even speed.

Valve mechanism
The valve mechanism actuates the valves, causing them to open and close at the right times.
The camshaft is located high up and driven by the timing gears. It rotates at half the speed of the crankshaft.
The camshaft cams (lobes), two for each cylinder, actuate the valve tappets.
The pushrods are inside the valve tappets and transmit, via the rocker arms, the movement from the camshaft
lobe to the valves.
At one end of the rocker arm is an adjusting screw so that the correct clearance can be set to ensure that the
valve will close properly during combustion.
The valves seal against valve seat rings which are pressed into
the cylinder head.
The valve seat ring can be replaced.

Transmission
Gear drive
Important components such as the injection pump and valve mechanism require precise control and are
therefore driven by gears.
By means of an intermediate gear, the gear on the crankshaft drives the camshaft and oil pump.
The camshaft gear in its turn drives the gears for the injection pump, coolant pump and fan.
To facilitate correct assembly of the timing gears, the gears are marked on a tooth or in a tooth space.
1. Crankshaft gear
2. Intermediate gear
3. Camshaft gear
4. Gear for coolant pump
5. Gear for fan drive
6. Gear for injection pump
9. Gear for oil pump

Belt drive
It is two belt drives, one for the alternator/air compressor and
one for the AC compressor.
In the large gears is a retaining ring for damping oscillation,
which also reduces the noise level.
A. Alternator
B. Air compressor
C. AC compressor

Lubrication system
Oil pump
The lubricating oil is sucked from the sump through a strainer in
the oil pump.
The oil pump is of gear type driven by the engine timing gears.
Incorporated in the oil pump is an oil pressure valve which
prevents the pressure from becoming too high.
Oil pressure must be sufficiently high for the required quantity
of oil for lubrication and cooling to reach each lubrication point.
Too high oil pressure could cause excessive stress to
components in the lubrication system.
When the oil is cold the pressure is more likely to be high and
for this reason an oil pressure valve is integrated into the oil
pump. If the pressure is too high the oil pressure valve will allow
oil to escape (and run back to the sump), so that the pressure
never rises high enough to cause any damage.

Oil cleaner
The lubricating oil continues to the oil cleaner, which consists of
two parts: cyclone cleaner and centrifugal cleaner.
The oil is caused to rotate in the cyclone where particles of dirt
and some of the oil are separated from clean oil through
centrifugal force. The clean oil is subsequently distributed to all
the various lubrication points.
The oil containing particles of dirt is forced up into the oil
cleaner’s centrifuge.
The centrifugal cleaner’s rotor is caused to spin by the force of
the oil which squirts out through two nozzles at the bottom of
the rotor.
Particles of dirt are forced against the wall of the rotor by
centrifugal force where they become attached as a deposit.
The rotor must be dismantled and cleaned at definite intervals.

Oil cooler
The oil passes from the oil cleaner to the oil cooler.
All the oil goes through the oil cooler, which is cooled by coolant
from the cooling system.
Lubrication oilways
Oilways in the cylinder block carry oil to the camshaft bearings
and crankshaft main bearings.
The big-end bearings receive oil through oilways in the
crankshaft.
Lubrication oil to the rocker arms is lead through an oil way in
one of the camshaft pivot pins.
These oilways are opened once for each revolution of the
camshaft and provide the correct quantity of oil to the rocker
arms.

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Turbo filter
The oil to the engine’s turbocharger must be especially clean.
It therefore goes through a further purifying stage, a filter
cartridge with a paper filter.
The filter cartridge also has a valve which can release oil to the
turbocharger if the filter becomes blocked.
The filter should be changed at the intervals given in the Scania
inspection programme.
The pistons are cooled by engine oil which is sprayed into an
oilway in the piston by piston cooling nozzles, one for each
cylinder,

Turbocharger
The purpose of the turbocharger is to increase the volume of air
entering the engine’s cylinders. With more air the engine can
burn more fuel and so develop more power and achieve
cleaner combustion than a corresponding engine without
supercharging.
The turbocharger is driven by the engine’s exhaust gases and
consists of a turbine part and a compressor part. The
compressor part compresses the engine’s intake air.
The turbocharger’s shaft runs in a bearing housing between the
turbine wheel and compressor wheel.
Higher power output from the engine gives more exhaust fumes
and the increased exhaust means that the turbine wheel and
therefore the compressor wheel rotate faster. In this way, the
quantity of air is adapted to engine requirements without any
special control devices.
The turbocharger wheel rotates extremely fast. At full power,
speed is about 100,000 rpm. At the same time, the temperature
on the exhaust side of the turbine wheel is above 600 °C.
This makes big demands on the rotating parts in regard to
balance, cooling and lubrication.
The shaft is mounted in two bushings which rotate freely in the
bearing housing. The bearing housing seals for the turbine and
compressor consist of seals which are similar to piston rings.
High-output engines for pleasure boats (750 hp) have two
water-cooled turbochargers.

Charge air cooling
1. Charge air cooler
2. Coolant radiator
3. Intake piping for air
By cooling the air after the turbocharger, more air can be pressed into the cylinders, more fuel can be burnt
and more power can be developed by the engine.
Some engines therefore have a charge air cooler (“intercooler”).
Liquid-cooled, DSI, with the charge air coolers mounted in the intake manifolds.

The cooling system keeps the engine’s operating temperature at a suitable level when the engine is in use.
This is of major importance for the engine’s operating economy and service life.
Complete cooling systems for Scania engines have a sufficiently high capacity for working at atmospheric
pressure, which ensures a more reliable system.
Scania cooling systems are therefore supplied as standard without a pressure cap.
A complete cooling system for DSI14 engine consists of:
- The engine’s internal cooling system:
• Coolant passages in cylinder block and cylinder head.
• Oil cooler for engine oil.
• Coolant pump.
• Thermostat housing with thermostat and bypass duct.
- External cooling system:
• Radiators and expansion tank.
• Temperature gauge and level indicator.
• Cooling fan
• Lines (pipes and hoses).
• External heat sources (e.g. cab heater) connected to the cooling system.
• Engine heater.
Cooling system
1. Expansion tank
2. Radiator
3. Static line
4. Drain tap
5. Coolant pump
6. Thermostat housing
7. Cooling fan
8. Fan ring
9. Venting lines
10. Level indicator

Doosan mt40 b articulated dump truck service repair manual

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Doosan mt40 b articulated dump truck service repair manual