Oil Pressure 60PSIG at startup 20PSIG at warmest

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gtuturbo
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Oil Pressure 60PSIG at startup 20PSIG at warmest

Postby gtuturbo » Wed Mar 11, 2015 8:54 pm

Ok so I always remember my gauge being about halfway or a little above and below since it was new.
Spun a rod bearing at Detroit Bfest. Replaced the engine in 2009.
It has a replacement Melling M95B with a pink spring which is a 70 psi relief.
Dash gauge then read about 60 psig. Cool to me.
Here we are about 4000-5000 miles later and it started at 60 and now drops to 20 on the dash gauge.
Took off the sender and it was time to replace as the connector was filled with oil and it is original.
Put on a pressure gauge and it reads the exact same so obviously the sender was still working BUT getting old and leaking so I am changing it.
Oil looks great with same as always 5W-30 and I don't suspect bearing clearances considering the engine is still new as far as mileage.
The rule of thumb is about 10psi per 1000rpm BUT this much lower than this pump puts out stock new.
So now I am turning my attention to the oil pump.
Here are my questions:

1. What is the pressure relief spring rated at stock? I am guessing 35-40 psi?
2.Anyone had problems with these pumps springs failing early?
3. Would the benefits of a high volume pump warrant the additional expense?
4. Most reliable brands besides OEM?

First post in a long time !! :D Thanks in advance.


Paul Keller
1988 Chevrolet Beretta GTU (turbocharged) (bought new in August 1988)
1966 Oldsmobile Cutlass Convertible
2017 Jeep Patriot High Altitude
2015 Buick Encore
2015 GMC Acadia SLE-1

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1988GTU
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Re: Oil Pressure 60PSIG at startup 20PSIG at warmest

Postby 1988GTU » Thu Mar 12, 2015 3:44 am

40-45 has always been the shop number I've relied on
Yes, and it was identifiable once removed and taken apart for what the culprit was in the pump
No, unless you increase capacity and have a need for the additional oil. Otherwise, it'll create a 'wash' of the oil rather than lubricate as well as rob more power away
Melling has been the default for OEM replacement, but it really doesnt matter as everything is outsourced and made offshore somewhere outside the US


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Re: Oil Pressure 60PSIG at startup 20PSIG at warmest

Postby SuzukiGhostRider » Thu Mar 12, 2015 4:45 pm

I assume this is a v6?


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gtuturbo
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Re: Oil Pressure 60PSIG at startup 20PSIG at warmest

Postby gtuturbo » Tue Mar 24, 2015 12:17 am

OK, I put an OEM oil pump on and tested again. This time I had 55psig at startup and 15psig at the time the fan relay picked up. Pretty close to the Melling, but it is also old.
The pump puts out 45psi at 2200 RPM when at normal operating temp. and that is max pressure whether rpm is increased or not.

I called both Melling and Sealed Power and their data indicates their pumps run at 20psi at idle. At this point I am replacing the sender and calling it good.
Between what the vendors have said and what data I have gotten by testing, my idle oil pressure is normal for the V6. If anyone has tested their oil pressure at idle and disagrees with my analysis , I welcome their opinion.
If anything, I am taking my gauge assembly to work and callibrating the oil pressure gauge and sender together at 90 ohms at max and 0 ohms at min per the shop manual info.


Paul Keller
1988 Chevrolet Beretta GTU (turbocharged) (bought new in August 1988)
1966 Oldsmobile Cutlass Convertible
2017 Jeep Patriot High Altitude
2015 Buick Encore
2015 GMC Acadia SLE-1


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