Emissions - Crankcase Ventilation System Info.
SI M11 07 08Engine
March 2011
Technical Service
This Service Information bulletin supersedes SI M11 07 08 dated March 2011.
[NEW] designates changes to this revision
SUBJECT
Crankcase Ventilation System Diagnosis and Measurement
MODEL
All
INFORMATION
All current MINI engines incorporate a pressure-controlled crankcase ventilation system. The crankcase ventilation systems use various different crankcase ventilation valves, depending on the engine type. 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 (underpressure) in the crankcase, which assures reliable crankcase venting during all engine operating conditions. Some of the causes and results of a malfunctioning crankcase ventilation system are listed below.
Causes of Excessive Overpressure (Pressure)
^ Internal engine damage/wear
^ Obstruction in the crankcase ventilation system
^ Defective pressure control valve
Results of Excessive Overpressure
^ Damage to the engine oil seals
^ Increased engine oil consumption (can be misdiagnosed as a defective turbocharger)
^ Excessive engine oil in the intake system
^ Excessive engine oil in the charged intake tubes or the intercooler on turbocharged engines (can be misdiagnosed as a defective turbocharger)
^ Engine oil dip stick is dislodged from the guide tube (if equipped)
Cause of Excessive Underpressure (Vacuum)
^ Defective pressure control valve
Results of Excessive Underpressure
^ Damage to the engine oil seals
^ Increased engine oil consumption
^ Excessive engine oil in the intake system
^ Rough engine idling or engine misfire
^ Whistling or howling noise from the engine (can be misdiagnosed as a defective turbocharger)
^ Increased mixture adaptation values
Attached to this Service Information bulletin are two procedures:
1. Preparing an engine oil cap for a crankcase pressure measurement
2. Measuring the crankcase ventilation system using the ISID and IMIB diagnostic equipment
Specification and actual readings from the vehicle may vary by up to +/- 10%, but not more than 4.0 mBar.
WARRANTY INFORMATION
This service information bulletin is intended to provide technical diagnostic and/or repair information.
Claims that result from the repair of a verified defect are to be processed following established warranty policies and procedures.
ATTACHMENTS
M110708_Engine_Oil_Cap_Modification
M110708_Measuring_Crankcase_Pressure_Using_IMIB.