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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 87_Silverado on October 06, 2009, 07:59:42 am
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Hey guys, I just bought an '87 SWB 350, and one of the first things I noticed was that the oil pressure was really high, like maybe 70psi at idle, well above the highest marking on the gauge (60.) I asked the owner what was up and he said that it has always run that high and that they even took out the gauge and sending unit and measured and it was verified.
My question is this: does this high of pressure cause any problems? I searched here on the forum and didn't really see anything about this subject. I have always heard that you want around 10 psi per 1,000 rpms and any lower you run into problems, but what about higher? I changed the oil thinking maybe they had been overfilling it, but the pressure is still reading the same. Any thoughts?
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Is it a stock motor? Is this the pressure at idle? What weight oil did you put in it?
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As far as I know it's the stock motor (it certainly doesn't feel like it's been built.) The PO said that he thought that his son-in-law that owned the truck before him may have rebuilt the motor, but he doesn't know. I put 10W30 Mobil 1 in it when I changed the oil, and yes over 60+ psi at idle. It seems like it has to be the gauge, right?
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It would guess it is the wrong sending unit.
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I agree! My new 350 i just put in my 86 has a hv pump and sold startup is about 70ish and hot idle about 200deg is 35
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Hook a manual gage up to it and see what pressure is, if you are truly getting 70 psi at idle on cold start up you could see 90-100 psi if this is fact don't rev that baby up cold you will leave shell of oil filter in drive way