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oil pressure 20# at idle and 45# reved up. is that low?

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Old 07-25-2010, 07:09 PM
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Exclamation oil pressure 20# at idle and 45# reved up. is that low?

this is my 1st ls1 and i was told that those number are pretty low.

any truth to that? i am about to the point of pulling the pan and checking the pickup tube and o-ring. is there another o ring that gets pinched in the pump?
Old 07-25-2010, 07:13 PM
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thats low for an ls1 yes... change the oil and filter and see if that helps... the only other thing i can think of is if the o-ring for the oil pump is bad. my bet is the first one.
Old 07-25-2010, 07:31 PM
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thanks. well i did put heads, cam, oil pump, lifters, etc in there. i put it in a 69 camaro so i have no background on the motor.
Old 07-25-2010, 07:34 PM
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I wish my oil pressure was that low! Probably worth 5-7 hp over 45/70 that I have now..
Old 07-25-2010, 07:37 PM
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Originally Posted by Paint_It_Black
I wish my oil pressure was that low! Probably worth 5-7 hp over 45/70 that I have now..
LOL, that is not something to wish for
Old 07-25-2010, 07:49 PM
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40 (psi, I suppose) is what mine usually runs idling hot. Who says the gauge is always right though? Like BennyB suggested, definitely change the oil and filter to eliminate that possibility first.
Old 07-25-2010, 08:51 PM
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run a search. I know alot of guys on here still quote the 10 psi for every 1k rpm rule. It is not that uncommon if the motor has some age on it to show a lower psi when warmed up. Most of this being due to clearances and normal wear and tear. Mine will drop to 30 on the 100 degree days sitting in traffic.

Is your car auto or manual. If it is a manual that could also be a reason you would read a little lower at idle.
Old 07-25-2010, 08:57 PM
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it is a 6 speed. i plan to tear into it tomorrow for peace of mind.
Old 07-25-2010, 10:44 PM
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Originally Posted by SatisTraction
it is a 6 speed. i plan to tear into it tomorrow for peace of mind.
I had a similar issue and changed the oil and filter and it stopped, others have posted that they have had the same issue and results too.

I would check the guage before I checked the motor also.
Old 07-25-2010, 11:40 PM
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An LS1 needs SEVEN pounds of oil pressure to float the crank at idle. Change the oil, maybe put a K&N oil filter on it (they flow extremely well, I noticed an 8 psi increase across the board over an AC Delco filter) but other than that leave it alone.
Old 07-26-2010, 02:10 AM
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Both the LS1's I have swapped into my '73 read about 25psi give or take a couple PSI depending on temperature, and would be about 40-45psi or so cruising down the road. Close to redline it'd be about 65PSI. This is on Stewart Warner Electrical gauges. I did hook up a mechanical gauge once to diagnose a bad oil pump and found my electrical SW gauge read a bit low.

I'd say your fine.
Old 07-26-2010, 02:39 AM
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it's a little low, but on hot days or before an oil change mine will read about the same. General rule as was said before is 10 psi per 1k rpm. Change the oil and you should be pretty good.
Old 07-26-2010, 04:04 AM
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If this is an engine with stock clearances, then I would check the o-ring like you are doing. Sounds low to me.

Now, if you had a rebuild, and have other than factory clearances, then it may be normal.
Old 07-26-2010, 10:58 AM
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Originally Posted by Grimes
If this is an engine with stock clearances, then I would check the o-ring like you are doing. Sounds low to me.

Now, if you had a rebuild, and have other than factory clearances, then it may be normal.
+1, if stock clearances of IIRC 0.001 then your o-ring is pinched/ripped/FUBAR BUT if this is rebuilt with IIRC 0.0025-0.003 then you should be fine.

The pressure is adequate in either circumstance, but if you have stock clearances, then I would definitely check the o-ring, you don't want a piece broken off floating around somewhere.
Old 07-26-2010, 12:08 PM
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what O ring are you refering to? the pickup oring or one in the oil pump? i may just check both for peace of mind.
Old 07-26-2010, 12:17 PM
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Weird, the 1999 Formy I have runs about 20-30 at idle. However it idles at about 500rpm. Now my 1989 with a LQ9 runs about 40-45 at idle, and idles at 950rpm.

Do you still have good pressure at cruise and under load? I usually see about 55-60 psi under load or highway cruise.
Old 07-26-2010, 12:34 PM
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45 or so at cruise and under load. it never goes down while getting on it.
Old 07-26-2010, 02:20 PM
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Originally Posted by SatisTraction
what O ring are you refering to? the pickup oring or one in the oil pump? i may just check both for peace of mind.
pickup tube
Old 07-26-2010, 04:48 PM
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Originally Posted by 1SLwLS1
pickup tube
But if it was leaking between the pump and engine that would also cause low pressure,

as I already said I would check the guage before you check the motor. but thats just my $.02
Old 07-27-2010, 11:26 AM
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Originally Posted by 00pooterSS
But if it was leaking between the pump and engine that would also cause low pressure,

as I already said I would check the guage before you check the motor. but thats just my $.02
If it was leaking anywhere, it would cause low pressure, even the cam retainer plate.


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