Low oil pressure at hot idle
05-23-2011, 02:17 PM
#21
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same deal with my '95 Trans Am...6-8 lbs at hot idle. i never hear the motor clicking and under throttle she runs back up. my dad was an ase certified master mechanic for Gm and said those gauges saw those readings straight off the trailer from Gm...nothing to sweat.
05-23-2011, 09:34 PM
#22
My engine had (past tense) 40 PSI at hot idle with 5W-30 for years. (For the record, it had a new OPS too.) It had a Melling standard pressure /standard volume pump. (It had been replaced at 70K miles when the motor was rebuilt.)
About a year ago, the oil pressure at idle started to slowly creep down, until last month it fell to about 17-23 PSI. That was enough. I replaced the pump with a Melling High Volume (NOT a high pressure) pump; now it's back to 40 PSI at hot idle (and 75 PSI at WOT).
Now, in the spirit of full disclosure - my car has 182K miles and the last 40K have been with a turbo pushing 11 lbs of boost, so are my main bearing clearances opened up just a touch? Yes, I would say they are indeed, but prior to me thrashing it, it did indeed have 40 PSI at hot idle.
Last edited by great421; 05-24-2011 at 07:23 AM.
03-12-2018, 02:38 PM
#23
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Oil Filter So i wanted to share my experience. I have been chasing this problem for a week now and am happy to report that when i changed my crap FRAM oil filter, my oil pressure came back to 60 on a cold start. Long story short i bought another lt1 z with a corvette motor from a 93 vette. Car runs great but the oil pressure kept getting really low in the red. So after reading everyones experiences i did the troubleshooting. Hooked a mechanical gauge up to find out the factory one is dead on. So that crossed out the OPSU. Then changed the oil type to 10w30 mobile 1. Didn't help, and after sitting in DQ drive way i saw the oil pressure go to ZERO. I shut it down and let it sit for a few and fired it back up. Came back up to about 15 psi, so i ran it home fast making sure to throttle it from going low again and parked it. This morning for ***** and giggles i bought a K&N oil filter and just replaced the filter without changing the oil again. I installed it and fired it up and BAM right to 60. Shut it down and topped it off and fired it back up and it has been running about 15-20 warmed up. Thanks for all the help everyone and im glad to know my car doesn't have any other issues yet.
Just a quick question though? Can this be prevented so the motor does not become junk when it spins a bearing? I have read at the oil pump can be upgraded to help this. Does this really help and how hard it is? Any other tips.
Just a quick question though? Can this be prevented so the motor does not become junk when it spins a bearing? I have read at the oil pump can be upgraded to help this. Does this really help and how hard it is? Any other tips.
03-12-2018, 03:44 PM
#24
FWIW my 35k mi 383 was built with slightly wider bearing clearances and came with a Mellig HV pump.
Cold idle is 55 PSI and Hot idle is 45 psi
A HV oil pump should not be used in motors with stock bearing clearances IMHO.
People have swapped the stock spring from the oil pump to the GM pink one for more "pressure"...which may help ageing motors with worn bearings keep decent oil pressure
Cold idle is 55 PSI and Hot idle is 45 psi
A HV oil pump should not be used in motors with stock bearing clearances IMHO.
People have swapped the stock spring from the oil pump to the GM pink one for more "pressure"...which may help ageing motors with worn bearings keep decent oil pressure
03-13-2018, 10:37 AM
#26
