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oil pressure at highway speeds  Rate Topic 
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 Posted: 01-18-2006 02:21 am
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Ron Mau
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Last summer after rebuilding the top end of an engine, I took it out on the highway the oil pressure was at 65 pounds and then it would drop about 10 lbs of pressure and then return to the 65 pound mark. Any ideas as to what is going on. Is an engine rebuild in order or do I just need to rebuild the oil pump. Or is it something else entirely?? Any assistance will be appreciated.

 

Ron Mau

JH 16367

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 Posted: 01-18-2006 05:43 am
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Mark Rosenbaum
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If it did this once only, then it was probably a momentary sticking of the oil pressure relief valve, or debris partially blocking the passage to the oil gauge pipe, or something similar.  Here, I wouldn't worry about it, particularly if it never happened again.   

If it did it repeatedly, with the lower pressure at lower engine rpm, and the higher pressure at the higher rpm, I'd think it normal behavior and wouldn't worry about it.

If it did it repeatedly, at a constant engine rpm, I'd be concerned about a sticking oil pressure relief valve, or excess end play in the oil pump rotors causing the pump to repeatedly lose then recover its prime.  Here, I'd slip off the timing belt and verify the end play of the aux. gear, and if it was out of spec would rebuild the oil pump.  But if the end play were in spec, I'd drive the car but watch the pressure very carefully.

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 Posted: 01-18-2006 09:07 pm
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Greg Fletcher
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I had on occasion once, many years ago with very low oil pressure that puzzled me. I removed the oil pump relief valve and found a small piece of silicon sealer in the spring. It looked like nothing at all, but I removed it, cleaned the spring, applied a small amount of assembly lube, reassembled and the oil was pressure was back to it's old self! Mostly dumb luck, but I felt like a genius at the time. I soon switched over to the rubber cam cover gaskets and never had a problem like that again.

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 Posted: 01-18-2006 09:08 pm
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Judson Manning
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Ron,

Didn't your son send me a pic of your snapped crankshaft?  Maybe that had something to do with it?????  lol

Judson

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 Posted: 01-18-2006 10:09 pm
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Ron Mau
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Judson,

Different engine, but I don't want the same outcome.

Ron

Ron

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 Posted: 01-19-2006 01:51 am
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Judson Manning
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Just giving you a hard time Ron...

Seriously, as I've mentioned before, I think the #1 upgrade to the JH oiling system is going to 180^ grooved bearings and x-drilling the crank.  The expensive way is using later Esprit bearings, the cheaper way is to use Chrysler 318 main bearings.

 

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