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Kevin, BMW Mechanic
Category: BMW
Satisfied Customers: 2162
Experience:  Diagnostic technician
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Recently had clutch replaced on 2003 540i M62. Had rear main

Customer Question

Hi, recently had clutch replaced on 2003 540i M62. Had rear main seal, rear main plate gasket, water plate gasket, front trans seal all done at same time. Worked great. approx 1 month later, starts losing ton of oil. Mechanic says rear main seal "sucked into engine" causing the big leak. He says its probably the CCV (crankcase vent valve) causing too much crank case vacuum. I don't want to replace it for no reason, and it doesn't sound possible to me. Thinking more likely the spring popped off the seal. 85k miles total. Thoughts?
JA: Have you ever replaced the gaskets? Maybe the hoses?
Customer: What gaskets and hoses? Question is, can a bad CCV cause enough crankcase vacuum to suck a rear main seal or spring into the engine? Or more likely a failed replacement job or bad seal? I have no other symptoms.
JA: Are you fixing your 540i yourself? What have you tried so far?
Customer: This is the first job I haven't done on my car myslef since I have owned it, 11 yrs. Was winter in NE when clutch went and I didn't want to do it in the cold in my driveway...nothing tried in this instance. All that replaced at one time, leaked a month later, trans out at shop and he says seal sucked into engine. Replace seal will solve prob of leak, but if it was caused by crankcase vacuum too high, it could happen again if not solved. But I would think it impossible, and Id have other symptoms if CCV was bad.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No, thanks.
Submitted: 2 months ago.
Category: BMW
Expert:  Kevin replied 2 months ago.

Hi im kevin a pcv valve works to equalist pressure between crankcase and cam case .so if the valve were to fail and stick closed if wouldnt cause vaccumme in the crankcase it would cause pressure .this would cause seal to pop out not get sucked in .however this is highly unlikely if part were fitted correctly

Customer: replied 2 months ago.
Hi Kevin, not sure you are answering the question I asked. The mechanic tells me he has read that the CCV (not PCV) going bad causes excess crankcase vacuum, and that over time it whistles from sucking air through the seal and eventually can suck the seal into the engine. The entire seal pulled into the engine, meaning the press fit metal to metal connection seal to rear main plate. I don't see how its possible, can't imagine how much suction it would take to pull the whole seal out of the plate. Also, there has been no whistle and no other symptoms at all. So what could cause this seal to pull out?
Expert:  Kevin replied 2 months ago.

In my opinion the only thing that can cause this is an incorrectly seated seal .this doesnt happen