High Oil Pressure

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Sep 22, 2001 | 09:18 PM

fpjungle

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High Oil Pressure

I have a 360 in my 69 F100 which was rebuilt about 15 years ago, but which has been in a garage for most of that time. I have started it a few times a year to try to make sure it would run when I found the time to "break it out". There is now about 1200 miles on it, and after running fine (45-60psi) for all these years in storage, it now pegs out my oil pressure gauge. A closer test with a snap-on gauge tells me it is 80psi at idle and 95psi when revving about 2500rpm. I changed the high volume oil pump to a Melling high volume oil pump with the same results. I took off the valve covers to make sure I was getting oil up top and it seems to be ok. I'm not sure what my next move should be short of tearing down to inspect bearings for blockage.
What I plan at the moment is to put on a Motorcraft racing high pressure oil filter and carefully drive it to see if the pressure will reduce with use, If it blows, I'll tear it down and hope for the best then. Any ideas or is this psi common?
Thanks, Chris

Sep 23, 2001 | 12:58 PM

dinosaurfan

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High Oil Pressure

Chris, is the pressure that high when the engine has warmed up ? I ran an old 352 for several years with a melling M57HV in it and 20W-50 with lots of motor honey mixed in. It started with over 100 lbs cold but gradually went down to 10 lbs at idle hot. I turned the idle up to 750 rpm because the low pressure frightened me. I had 15 lbs @ 750. Maybe you should be running thinner oil ? what is in it now ? DF

Sep 23, 2001 | 06:51 PM

fpjungle

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High Oil Pressure

Thanks for the response. I was running 15w40 until recently when I changed to 10w40. There is no change on the gauge when it warms up. Thermostat is a 180 and the engine does get hot. I've run it at idle on and of now for about 3 hours total.
Everyone I talk to says spun cam bearing. I'm praying I don't have to go through the block again, because I know it will be another few years before I get to it.

Sep 23, 2001 | 11:37 PM

Bullitt390

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High Oil Pressure

You need to start it up and the DRIVE it for like 20 miles or something. Just revving it in the driveway is not going to sufficiently warm the oil. Plus all that idling now and over the years has probably really gummed things up.

Change the oil and filter.

The drive it. 'Spirited' driving will loosen things up well. And then you will have an idea of what the engine is doing.

None of the parts stores or even Wal-Mart around even carry 10w40 anymore. Crazy.

Josh

Sep 29, 2001 | 06:37 PM

bigbadmonte

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High Oil Pressure

As far as i can tell, no matter the engine, if the engine has a problem with really high oil pressure, then it's usually a stuck pressure relief valve. I have a high volume pump in my car and cold start up at 2000 rpm will hit 100 psi with 10w30. It eventually warms up and idles at about 35 and runs at about 55. You also stated that you had a high volume oil pump, which would result in higher pressures. The only way to get the higher volume through the same plumbing is to incease the pressure. So i wouldn't really worry about it. Just give it a good running and next oil change run some Gunk motor flush through as per instructions on the can. I've found that stuff to unclog sticky lifters, so i know it does a decent job of flushing out any deposits from old oil.