Now the oil pressure is too low! 93 Regal 3.8 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 02-24-2012, 07:02 PM   #1
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Default Now the oil pressure is too low! 93 Regal 3.8

I have just finished installing a used engine in my 93 Regal 3.8. I had a problem with the oil pressure being too high and blowing oil filter gaskets. The problem was a stuck oil pressure relief valve which I repaired. See my recent link "Oil pressure problems - 93 Regal 3.8" below

The engine runs well now except now the pressure is too low (I think) - just below 40 when driving around and just above the red zone at idle and at "normal operating temp." I'd like that to be a little higher and came across Dan'* mod from a while back.

https://www.gmforum.com/showthread.p...t=oil+pressure

Question is, even though Dan cautioned to use only one washer, for my low pressure would two washers be ok? And now that I think of it, is my pressure good the way it is?

Thanks.

Rick
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Old 02-24-2012, 07:12 PM   #2
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When was the last time you changed the oil? Reason I ask is, when I do an oil change, my oil psi gauge will show high(above 40 psi). As time goes by, the psi will be high at first start up, then hover around 40 sometimes just a tad below 40.

I'm just wondering if the viscosity of your oil has broken down enough to where its not able to build enough pressure.
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Old 02-24-2012, 07:16 PM   #3
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Check the pressure with a mechanical pressure tester. The electronic one in the car isn't as reliable.
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Old 02-24-2012, 07:31 PM   #4
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The oil is new (maybe 5 miles on it) 10w-30 with a new ACDelco PF47E filter. The oil pressure sender unit is new as well but I'll see if I can get a mechanical unit in there.

Assuming the reading from the mech unit is close to my electrical, are my pressure readings ok, or should they be higher? I'm thinking they need to be higher, especially at idle.

Thanks for the help, guys.

Rick
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Old 02-24-2012, 08:04 PM   #5
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What oil pressure sender unit did you get?

I ask because I found that some cars are picky and won't show the right oil pressure unless you have the exact same sender, did you get the exact OE sender that was in there before?

Dan is right though, unless you get a mechanical oil pressure sender and gauge you'll never have accurate oil pressure readings.
Some day I plan to put a T where mine goes, that way I can have both of them working so I do not get a red light on the dash when my factory gauge is...
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Old 02-24-2012, 08:10 PM   #6
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My car is doing the exact same thing (2000 bonne ssei)... i jst had my valve cover gasket and valve cover done (because it had a hole in it).. dont know how or if its related but would like to know wht should i do about it, was thinking maybe its the oil pressure sensor...
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Old 02-24-2012, 08:45 PM   #7
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Around 40 is good, but if it'* dropping below about 20 that'* getting low.
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Old 02-28-2012, 08:01 AM   #8
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It was dropping to just above the red zone on the dash guage. I haven't been able to get a mechanical unit in there yet. Before I installed the engine (see my 1st post - https://www.gmforum.com/buick-172/oil-pressure-problems-93-regal-3-8-a-302109/) I replaced the oil pressure relief valve but did not replace the spring. Assuming that it might be weakened in some way I have ordered a new one. (Actually I ordered 10 of them because that'* the only way the GM parts guy could get them. If anyone needs one let me know. They're only about $1.20 each.)

The approach here is to eliminate all possible problems. Maybe the old spring was weaker in some way, or shorter, and a new one will get the pressure back up to where it needs to be. If that doesn't work I'll try Dan'* shimming approach. If that doesn't work then I'm up the creek.

To add to all that, sitting in the parking lot idling last night I picked up the faint sound of what is probably the rod beginning to knock. So the car is off the road until I mess around trying to get the oil pressure up to where it needs to be.

The engine is used and bought to replace the original one which died a while back. The rod journals looked to be in pretty good shape but I replaced the rod bearings. The one main bearing I inspected also appeared to be in pretty good shape so I didn't check the rest of them. Probably one of the others is bad and may be the cause of my low pressure, assuming the greater clearance from a really worn main journal/bearing would cause that. So I guess if I can't get the pressure up to where it needs to be I'm looking at a crank kit.

Comments, suggestions, etc. will be appreciated.

Thanks.

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