1. Technical Bulletin 05/07
Crankcase Ventilation System Check For
1994-2007 BMW Engines
The AERA Technical Committee offers the following information regarding the crankcase ventilation system
for 1994-2007 BMW engines. This information should be considered any time oil consumption issues are being
diagnosed.
Models affected: All with M42 (from 1/94), M44, M52, S52, M60, M62 and M73 engines.
Situation: All current BMW engines incorporate a
pressure-controlled crankcase ventilation system.
The crankcase ventilation systems use various
different crankcase ventilation valves depending
on the engine type, as shown in the illustration.
Although the valves all look different, they function
similarly using a spring and diaphragm assembly
to control the crankcase pressure. A properly
functioning pressure control valve is designed to
maintain a slight vacuum (approx. 10-15 mbar)
in the crankcase, which assures reliable crankcase
venting during all engine operating conditions.
A malfunctioning crankcase ventilation valve may cause the following complaints:
• Engine runs rough
• Whistling noise from the crankcase ventilation valve
• Check Engine Light on - possible DM faults stored: misfire all cylinders, oxygen sensor/mixture
faults, etc.
To assist in troubleshooting the above complaints, a special tool part number (99 00 0 001 410) has been devel-
oped to quickly check a pressure-controlled crankcase ventilation system. Also, refer to service information
bulletin number 04 08 98 for further information regarding the slack tube manometer tool.
The slack tube manometer tool consists of:
1. Slack Tube Manometer
2. Connecting Hose
3. Modified Oil Filter Cap
Follow the instructions included with the slack tube manometer for the initial tool set up and general operat-
ing procedures. Basic operation is as follows.
continued on next page
Information is from best available sources and is accurate at the time of publication. However,
Jasper Engines & Transmissions ASSUMES NO RESPONSIBILITY and cannot be held liable for any
results or consequences regarding the use of this information.

2. 1. Connect the slack tube manometer to the engine oil filter neck.
2. With both valves (1) open approximately 1/4 turn; zero the sliding scale using the knob (2) as
shown in Figure 2.
3. Start the engine and observe the column of water.
4. With all electrical consumers and the air conditioning
switched off, and engine at operating temperature,
the reading should indicate from 3.0 - 6.0 inches of
water at idle.
5. NOTE: The values on both sides of the slack tube
must be added together to get the proper reading
as seen in Figure 3.
6. Example: 2.5 + 2.5 = 5.0 inches of water.
(The readings may fluctuate 0.1 - 0.2 during
the measurement which is normal and does
not indicate a defect.)
If a crankcase ventilation valve is defective
(damaged diaphragm) the column of water will
indicate an off-the-scale reading (all of the
water on one side of the slack tube) which
designates a high crankcase vacuum.
7. NOTE: A higher than normal crankcase vacuum
will also cause the crankshaft seals to leak outside
air into the crankcase during engine operation.
A whistling or howling noise is usually heard
coming from the seal areas (front or rear), at idle,
when this occurs.