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440 oil pump o ring

69 mayflower

Well-Known Member
Local time
9:56 AM
Mar 13, 2011
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Fresh rebuild, engine break in went great. Ran engine several times driving up and down our road over the course of several weeks. All was well, then started losing oil pressure. Pulled the oil pump and discovered that the o ring on the pump shaft was not installed by the builder. Would this be the cause of my oil pressure loss? Right bank is the side that clattered before I shut it down, left bank appears normal. Installed new standard volume oil pump WITH o ring Going to prime again to make sure oil is making it to the rockers. Any advice, thoughts, or words of encouragement. Just hoping I didn’t spin a bearing.
Maybe you spit out a lifter. You might want to pull the valve covers and inspect the valve train.
Don't see the missing o ring sucking air or causing a problem. There is [ should be ] a paper gasket between the pump body & the block. This, by itself, should seal it. If air could get in, oil could get out....No oil leak reported.