BMW 6-cylinder Double Vanos Seals Solution
Do you own a BMW 6-cylinder car with M52TU, M54, or M56 engine, 3-series E46 98-05, 5-series E39 99-03 / E60 & E61 02-05, 7-series E38 98-01 / E65 & E66 02-05, Z3 E36 98-02, Z4 E85 02-05, X3 E83 03-06, X5 E53 00-06 ?
If so, then your vanos, engine variable valve timing unit, is most likely failing. BMW engines M52TU, M54, M56, utilize vanos part # 11-36-1-440-142. This vanos has been consistently diagnosed to fail due to deteriorating piston seal O-rings. These O-rings are made of a material that is failing in the engine environment. This causes the vanos piston seals to lose their sealing function and for the vanos unit to fail.
Symptoms are a loss of torque and power, bogging and hiccupping at lower RPM's (< 3k). M52TU engine cars (98/99-00) are also experiencing cold weather cold start engine idle jolts and possible stall.
BMW does not provide a vanos seals repair kit. It sells a rebuilt vanos unit for ~$500. New rebuilt vanos units are supplied with the same failing O-rings, and have been found to significantly fail in 20k miles (32k kilometers).
A vanos seals repair kit is now available. It incorporates upgraded O-rings to address the failure mode and replacement Teflon seal rings.