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Low oil pressure, WTF??

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Old 03-05-2008, 05:23 PM
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Default Low oil pressure, WTF??

So I go to taco bell for some food and on the way back go WOT through first and second then afterwards my oil pressure gauge is reading low, like 25-30psi at idle. It usually sits at 40 at idle. It goes up to the 40 area up to 2500 rpm's then goes up a lot when the push the rpm's up. When Im cruising along and i push the gas it drops slightly and then goes back up when I come off the gas. Like when its loaded the pressure drops a bit.

First thing I did was change the oil/filter and pulled the valve covers off and had a look. Everything looked OK so I buttoned it up and drove the car a little bit. It sounds fine and isnt skipping a beat at all. No ticking or stange sounds. I am suspecting either a bad pressure sending unit/gauge or a slowly failing oil pump. I almost 99% sure its not a rod bearing or anything like that. Once I get a mechanical gauge on it I can narrow it down a little more.

What do you guys think? This **** pisses me off.

Last edited by brad8266; 03-05-2008 at 05:29 PM.
Old 03-05-2008, 05:27 PM
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Have you had the oil pump off recently? It sounds like it could possibly be a bad o-ring on the pickup tube.
Old 03-05-2008, 05:27 PM
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Originally Posted by DaveX
Have you had the oil pump off recently? It sounds like it could possibly be a bad o-ring on the pickup tube.
No its been together for a year now, the o-ring is fine.
Old 03-05-2008, 05:30 PM
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when was the last time you changed your oil? mines doing the same thing, and i know when i change the oil itll go back to 40psi and upto60 at WOT

-brandon
Old 03-05-2008, 05:35 PM
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Originally Posted by Demonicbird00
when was the last time you changed your oil? mines doing the same thing, and i know when i change the oil itll go back to 40psi and upto60 at WOT

-brandon
Well I chaged it 10 minutes after the pressure dropped. Changing it really didnt do anything for the pressure. It still gets enough at WOT it doesnt have pressure at low rpms's like it did before.
Old 03-05-2008, 05:47 PM
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Mine is down to like 19 at hot idle. Im not worried about it.
Old 03-05-2008, 05:51 PM
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Originally Posted by blkbird
Mine is down to like 19 at hot idle. Im not worried about it.
Well maybe I wouldnt be concerned excpet for the fact that in less than 1 minute I went from a 40 PSI hot idle to a 25PSI hot idle. Something is wrong.
Old 03-05-2008, 06:01 PM
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what kind of oil, and filter you use? i notice my oil pressure drop when i used penzoil platinum, and k&n filter.. went back to mobil, and wix filter. my pressure is good now
Old 03-05-2008, 06:19 PM
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Originally Posted by stangkiller2005
what kind of oil, and filter you use? i notice my oil pressure drop when i used penzoil platinum, and k&n filter.. went back to mobil, and wix filter. my pressure is good now
I used mobil this time.
Old 03-05-2008, 06:22 PM
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hmmm.. only thing i can think of is maybe the oil pump is failing. i had that problem of it getting that low with my stock oil pump. at idle it would sit around the same psi u mentioned. i doubt yours is stock. so it seems wierd that you have this problem.
Old 03-05-2008, 06:28 PM
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Originally Posted by stangkiller2005
hmmm.. only thing i can think of is maybe the oil pump is failing. i had that problem of it getting that low with my stock oil pump. at idle it would sit around the same psi u mentioned. i doubt yours is stock. so it seems wierd that you have this problem.
Yeah its a ported LS6 pump. They still fail though sometimes. Im hoping its just the sender, that would be sweet.
Old 03-05-2008, 06:30 PM
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yea it would. i guess it would be easiest route to check first to. cuz we all know how fun the oil pump is! lol


hope you get it figured out and squared away soon!
Old 03-05-2008, 07:14 PM
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When the oring or pump are a problem at work, you will hear some lifter noise. I would check the oil pressure with a manual guage? or swap the oil pressure sending unit with someone you know? When I have a oring problem Ive always had some noise.
Old 03-05-2008, 07:41 PM
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Originally Posted by fossil
When the oring or pump are a problem at work, you will hear some lifter noise. I would check the oil pressure with a manual guage? or swap the oil pressure sending unit with someone you know? When I have a oring problem Ive always had some noise.
Yeah thats what i was thinking, I mean the motor sounds perfect. I have one of the most quiet head/cam ls1 cars I have heard and even with the low gauge it still sounds perfect. Thats why I am hoping its just the sender.
Old 03-05-2008, 07:47 PM
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Originally Posted by brad8266
Yeah thats what i was thinking, I mean the motor sounds perfect. I have one of the most quiet head/cam ls1 cars I have heard and even with the low gauge it still sounds perfect. Thats why I am hoping its just the sender.
What weight oil are you running? Do have excessive clearance from stock on crank and rods?
Old 03-05-2008, 08:33 PM
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Originally Posted by fossil
What weight oil are you running? Do have excessive clearance from stock on crank and rods?
5w 30. Not excessive really, I dont recall the numbers off hand.
Old 03-05-2008, 08:45 PM
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Dont forget guys..Those are dummy guages...20 bucks says if u change your pressure switch(sensor) youll have way different readings..i bet you sensor is going on the crapola side
Old 03-05-2008, 08:49 PM
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Originally Posted by SuperSport01LS6
Dont forget guys..Those are dummy guages...20 bucks says if u change your pressure switch(sensor) youll have way different readings..i bet you sensor is going on the crapola side
Thats what Im hoping. That will only cost me $20 and an hour of my time. Its juts weird that my readings are off as soon as I went WOT for a few seconds.
Old 03-05-2008, 08:52 PM
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20 really my cost on one is like 32...your getting a GM one right
Old 03-05-2008, 08:54 PM
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Originally Posted by SuperSport01LS6
20 really my cost on one is like 32...your getting a GM one right
well yeah 32 then, whatever it is.



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