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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Diesel Engine Discussion => Topic started by: Edorsett on April 21, 2020, 08:04:24 PM

Title: High oil pressure
Post by: Edorsett on April 21, 2020, 08:04:24 PM
I have a 1980 GMC Sierra grande with a 350 sbc and when I start it the oil pressure gauge is in the middle and after awhile this is where it ends up. What could cause this? (https://uploads.tapatalk-cdn.com/20200422/04a0c8bafa269a2f6fa20c6b859dc234.jpg)


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Title: Re: High oil pressure
Post by: bd on April 21, 2020, 09:18:02 PM
It is highly unlikely that at any defined, fixed or otherwise given engine RPM, the oil pressure would increase with an increase in temperature.  Hence, begin by verifying the actual oil pressure using a 100 PSI mechanical pressure test gauge, preferably tee'd off of the same oil galley as the factory sender.  Then as engine temperature changes compare the pressure indications of both gauges.  Once you've established a known baseline you can begin determining the cause of any differences.
Title: Re: High oil pressure
Post by: Edorsett on April 21, 2020, 09:27:35 PM
Ok thank you I will try that.


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Title: Re: High oil pressure
Post by: bd on April 22, 2020, 12:26:09 AM
BTW - oil pressure between 30 and 60 PSI for a stock engine is excellent, 30-35 PSI being quite common.  Once you've verified oil pressure using a proper test gauge, more precise help can be provided.
Title: Re: High oil pressure
Post by: Edorsett on April 22, 2020, 08:17:06 AM
Ok thank you


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Title: Re: High oil pressure
Post by: JohnnyPopper on April 22, 2020, 04:07:05 PM
Is it electric or mechanical?

If it's electric your circuit may be affected by 'heat' as in poor B+ connection or ground.
Title: Re: High oil pressure
Post by: Edorsett on April 22, 2020, 05:00:53 PM
Ok thanks!


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Title: Re: High oil pressure
Post by: Edorsett on April 22, 2020, 07:36:50 PM
Lol I did not wait long enough it went to the middle when it got up to operating temp sorry my bad


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