The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Andrewsteward on July 11, 2015, 03:40:12 AM
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I noticed an air leak corresponding to exhaust pressure coming from front of rhs rocker cover. (pff pff pff) I removed cover and the gasket was misaligned and hence not sealing well. To me it signifies the exhaust valve passing, and hence pressurizing the rocker area. I checked the compression and it was 150psi for both sides. I replaced the gasket and seems to be OK but to me this does not seem right?
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There is a certain bit of crankcase pressure during engine ops. Note the pushrod tubes provide large openings into the rocker box area. Pull the top cover and check the crankcase breather system.
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That is the sound that mine made when the center mounting stud on the valve cover pulled out.
There is nothing wrong with your exhaust valves or intake valves.
The crank case breathes as the piston go in and out.
So the crankcase gets pressurized as the piston come in releasing pressure thru the breather valve but then the CC goes to a vacuum or lower pressure as the pistons go out
They go in and out together not opposite of each other like a 4 cylinder.
It would not hurt to check the breather valve as Monty said but the sound you heard is normal.
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If the gasket was leaking then that will have allowed air into and out of the crankcase which is supposed to be as far as possible a sealed space.
I agree the sound is normal and unless there are other symptoms there is no reason to suppose the breather is faulty as it will never function properly while an air leak exists.
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Thanks again guys, a sigh of relief. i shall check the breather for good measure. :)