Technical Bulletin05/07

Crankcase Ventilation System Check For1994-2007 BMW EnginesThe AERA Technical Committee offers the following information regarding the crankcase ventilation systemfor 1994-2007 BMW engines. This information should be considered any time oil consumption issues are beingdiagnosed.

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 variousdifferent crankcase ventilation valves dependingon the engine type, as shown in the illustration.

Although the valves all look different, they functionsimilarly using a spring and diaphragm assemblyto control the crankcase pressure. A properly functioning pressure control valve is designed tomaintain a slight vacuum (approx. 10-15 mbar)in the crankcase, which assures reliable crankcaseventing 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 informationbulletin number 04 08 98 for further information regarding the slack tube manometer tool.

The slack tube manometer tool consists of:1. Slack Tube Manometer2. Connecting Hose3. 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.

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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.

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 conditioningswitched 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 doesnot indicate a defect.)

If a crankcase ventilation valve is defective (damaged diaphragm) the column of water willindicate an off-the-scale reading (all of thewater on one side of the slack tube) which designates a high crankcase vacuum.

7. NOTE: A higher than normal crankcase vacuumwill also cause the crankshaft seals to leak outsideair into the crankcase during engine operation.A whistling or howling noise is usually heardcoming from the seal areas (front or rear), at idle,when this occurs.