Yanmar 3gm30 Oil leak bonnet bolts - SailNet Community
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post #1 of 1 Old 10-22-2012 Thread Starter
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Yanmar 3gm30 Oil leak bonnet bolts

Oil will occasionally weep up from the bolts and the breather on top of the bonnet on my 3gm30f, apparently due to excessive oil pressure. I've heard this may be caused by an obstruction in the breather, which sits on the rear of the bonnet, so I took the breather off but it looked spotless. I have also heard cylinder blowby may be to blame, but I just had the head taken off for unrelated maintenance (rusted-on fuel injector) and noted the cylinder walls were "like new". You can still see the original scoring from the factory.

Are there any other possibliities for why I would suddenly start experiencing oil weeping from multiple locations on the bonnet? The leaks are minor, but it's still an issue in my book.

I just bought the boat last year and change the oil religiously with Shell Rotella. The oil level is never quite filled to the top mark on the dipstick. Engine is 2003 in great shape and runs well with 2000 hours.
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