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Old 03-10-2006, 10:32 AM
Lscman Lscman is offline
Officially Welcomed to the 'Fest
Location: PA
Join Date: Aug 2003
Posts: 344
Mein Auto: 540i 6spd
Good search job. I see you found my post about the "primary root cause" for cat failure. Engine misfire for any other reason or fuel delivery system malfunction can cause cats to burn up. What more can I say...

If you search some more, you'll find my threads that caution 540i owners about crankcase ventilation problems. Tech Tips shows repair methods, but a thorough fix involves removal of the intake manifold to ream out vent piping. The rear cover diaphram valve clogging or failing is generally only symptomatic. Positive pressure cause the oil seals to fart and make a buzzing/whirring sound. This can really screw up your motor seals and gaskets.
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