The Crankcase Ventilation System (also known as PCV, or Positive Crankcase Ventilation) on the later model BMW V8 and 6-cylinder engines typically consists of a check valve (PCV valve), an oil separator and various vent and vacuum hoses. We have found that all of these applications (both V8 and 6-cylinder) have been experiencing failures of various parts of the system. The diaphragms in the check valves rupture, the check valves crack, the hoses deteriorate and oil sludge builds up in the hoses and valves that can partially or fully clog, or block, the system. We have designed kits for both the V8 and the 6-cylinder applications that give you everything that you’ll need in order to repair and renew the crankcase ventilation systems.
Follow along, with these three videos, as we perform the replacements on a 2001 325xi:
Below, is a photo of the check-valve/oil-separator and hoses, in the installed position. This photo was taken on an engine that was removed from the vehicle. You cannot see this view with the engine installed. Photo used here, compliments of Bentley Publishing, www.bentleypublishers.com.
In the DIY videos, we replaced all of the hoses and the oil separator and check valve, on the M54 (and M52TU) 6-cylinder engine. The system consists of a number of ventilation hoses, an oil separator and check valve and an oil drain-back hose. The system is well known to have problems with vacuum leaks due to hose and valve deterioration and cracking, as well as clogging due to sludge build-up in the hoses, valve and oil drain-back.
We typically get into the system when we see the symptoms appear, such as; oil burning, rough idle, engine fault codes that suggest air/fuel mixture problems or oxygen sensor problems and other symptoms that would suggest vacuum leaks in the system’s ventilation hoses or a ruptured check valve diaphragm. We have also seen what could be considered a catastrophic level failure which causes the cylinders to ingest oil right out of the crankcase and into the intake manifold and finally the cylinders … causing hydraulic lock. We are typically seeing these systems fail at mileages between 50,000 and 100,000. With these thoughts in-mind, you certainly would not go wrong in performing this task as a preventative maintenance operation.
Most (if not all) US model M54 (and M52TU) engined BMWs were delivered with the standard warm weather systems. The kits that we offer includes the hoses and valve assembly from the “cold weather” package. The hoses and valve are insulated with molded foam insulation. This can help to prevent the build-up of condensation in the hoses and the separator valve (which leads to sludge build-up and possible clogging of the ventilation hoses, valve or the oil drain hose). Even if you do not live in the northern climates, these parts are a good choice and will help to prevent the sludge build-up in the system.
In the early days of these failures, the generally accepted repair procedure (in order to replace the hoses and the valve) was to remove the intake manifold for access to all of the parts. We have found that the repair can be accomplished without removing the manifold. This greatly reduces the complexity and time of the repair.