Low Oil Pressure, Possible Causes??
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From: Olmsted Falls, OH
Low Oil Pressure, Possible Causes?? Need a little brainstorming here.
The problem is real low oil pressure. The new motor has had low oil pressure from the get go. 30 on cold start, warm 20 at idle (oil temp over 220°). Drops below that if the temps near 250°.
I've check the obvious, pump was new w/ the motor build. Pulled it already, relief is not sticking open and seats properly when closed. No obvious damage to pump gears. Pickup tube o-ring is in place, not cut or damaged (new in fact). Rear plug under the rear cover is in place. Just replaced it to be sure. No leaks i can find.
Pressure comes up with engine speed and light throttle. Heavy throttle and it drops to just over 20, as soon as i get out of it the pressure spikes to 50+.
Turbo oil feed check valve is in place and functioning properly. May try a smaller inline orifice to further limit the flow.
No excessive bearing material in the oil. A few small flakes, but i expect that with only 1k miles on the motor.
What else will cause the pressure drop? Bearing clearances were all on target when the motor went together. Will low lifter preload cause a drop? I know i'm only loading them about .04 when cold, 7.3" pushrods.
Ideas??
thanks
The problem is real low oil pressure. The new motor has had low oil pressure from the get go. 30 on cold start, warm 20 at idle (oil temp over 220°). Drops below that if the temps near 250°.
I've check the obvious, pump was new w/ the motor build. Pulled it already, relief is not sticking open and seats properly when closed. No obvious damage to pump gears. Pickup tube o-ring is in place, not cut or damaged (new in fact). Rear plug under the rear cover is in place. Just replaced it to be sure. No leaks i can find.
Pressure comes up with engine speed and light throttle. Heavy throttle and it drops to just over 20, as soon as i get out of it the pressure spikes to 50+.
Turbo oil feed check valve is in place and functioning properly. May try a smaller inline orifice to further limit the flow.
No excessive bearing material in the oil. A few small flakes, but i expect that with only 1k miles on the motor.
What else will cause the pressure drop? Bearing clearances were all on target when the motor went together. Will low lifter preload cause a drop? I know i'm only loading them about .04 when cold, 7.3" pushrods.
Ideas??
thanks
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From: Melbourne, FL
Re: Low Oil Pressure, Possible Causes?? No real ideas here for you Harlan, but I hate to see that you're having problems with the new motor. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
I would suggest verifying that the oil pressure sender is working correctly, but the fact that your pressure spikes to over 50psi when you let off the throttle would pretty much rule that out.
What kind of oil are you using? I have to run a thicker oil with my bearings set up for "race" clearances. Did you set all the bearings up for stock clearances?
Hope it's something simple that you get fixed quickly!
I would suggest verifying that the oil pressure sender is working correctly, but the fact that your pressure spikes to over 50psi when you let off the throttle would pretty much rule that out.
What kind of oil are you using? I have to run a thicker oil with my bearings set up for "race" clearances. Did you set all the bearings up for stock clearances?
Hope it's something simple that you get fixed quickly!
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From: Olmsted Falls, OH
Re: Low Oil Pressure, Possible Causes?? Well
I'm running a mechanical gauge off the block just above the filter. Turbo feed, oil pressure and oil temp is taken from there. factory gauge is doing about the same as the mechanical, but is slower to respond.
I've run multiple weights of oil to check things. 5w30 and 10w40 dino, and i'm on 15w50 synthetic right now. same deal.
rod and mains were all about .002 to .0025 measured with a bore gauge and micrometer. no plasti gauge <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
The only thing i can think of is maybe the turbos are pulling ALOT of oil. I do look like i'm dusting crops when at WOT <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
http://harlan.sketchy.net/eviltwin/Harlan2.wmv
I know i'm not burning oil in the motor, plugs are clean, intake plumbing is all dry, leakdown is 4% across the board, compression check is all 155+ psi cold and dry.
I'm running out of things to check <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
<small>[ September 27, 2002, 07:27 AM: Message edited by: y2khawk ]</small>
I'm running a mechanical gauge off the block just above the filter. Turbo feed, oil pressure and oil temp is taken from there. factory gauge is doing about the same as the mechanical, but is slower to respond.
I've run multiple weights of oil to check things. 5w30 and 10w40 dino, and i'm on 15w50 synthetic right now. same deal.
rod and mains were all about .002 to .0025 measured with a bore gauge and micrometer. no plasti gauge <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
The only thing i can think of is maybe the turbos are pulling ALOT of oil. I do look like i'm dusting crops when at WOT <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
http://harlan.sketchy.net/eviltwin/Harlan2.wmv
I know i'm not burning oil in the motor, plugs are clean, intake plumbing is all dry, leakdown is 4% across the board, compression check is all 155+ psi cold and dry.
I'm running out of things to check <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
<small>[ September 27, 2002, 07:27 AM: Message edited by: y2khawk ]</small>
Re: Low Oil Pressure, Possible Causes?? I'm no expert at this Matt, but wouldn't you get a different pressure from the point you are measuring? The factory sender sits atop a long tube which has a plunger type check valve (in the back of the block under the rear cover). I would think this plunger acts to regulate the pressure somehow to the factory sensor. Since you are not reading from that location, and there is no plunger enroute to the sensor, wouldn't it read differently?
Do you know the little plastic plunger I am talking about? If you left it out, that is likely your problem. If you did, do not drive the car any more until you fix it. Seen it toast someone's bottom end already <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
Do you know the little plastic plunger I am talking about? If you left it out, that is likely your problem. If you did, do not drive the car any more until you fix it. Seen it toast someone's bottom end already <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
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From: Olmsted Falls, OH
Re: Low Oil Pressure, Possible Causes?? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Reckless:
<strong>Do you know the little plastic plunger I am talking about? If you left it out, that is likely your problem. If you did, do not drive the car any more until you fix it. Seen it toast someone's bottom end already <img border="0" title="" alt="[Sad]" src="gr_sad.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I pulled both covers, front and rear on monday to check the pump and the plastic plug. I replaced the plug on wednesday to macke sure. So i know it's in there and fully seated.
It's only there to seal the main galley from the pump to the filter, and direct the oil from the pump into the pan/filter and back up into the block. no regulation there.
I actually read less pressure at the factory sender than the mechanical, that's what made me ask about lifters. Maybe the top end is pissing oil all over in the motor?? <img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" />
<strong>Do you know the little plastic plunger I am talking about? If you left it out, that is likely your problem. If you did, do not drive the car any more until you fix it. Seen it toast someone's bottom end already <img border="0" title="" alt="[Sad]" src="gr_sad.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I pulled both covers, front and rear on monday to check the pump and the plastic plug. I replaced the plug on wednesday to macke sure. So i know it's in there and fully seated.
It's only there to seal the main galley from the pump to the filter, and direct the oil from the pump into the pan/filter and back up into the block. no regulation there.
I actually read less pressure at the factory sender than the mechanical, that's what made me ask about lifters. Maybe the top end is pissing oil all over in the motor?? <img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" />
Re: Low Oil Pressure, Possible Causes?? Sure hope you figure it out before Tuesday. If so, are you still coming down to Norwalk?
Sounds like the mains were set up correctly, so not really sure what else <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Todd
Sounds like the mains were set up correctly, so not really sure what else <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Todd
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From: Olmsted Falls, OH
Re: Low Oil Pressure, Possible Causes?? Yeah, i'll figure it out by then <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Kinda glad we got rained out today <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Still got the day off though, have to get my new hoosiers mounted <img border="0" alt="[Firebird]" title="" src="graemlins/formula.gif" />
Still got the day off though, have to get my new hoosiers mounted <img border="0" alt="[Firebird]" title="" src="graemlins/formula.gif" />
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Re: Low Oil Pressure, Possible Causes?? Have you tried running more oil in the motor? Say an extra quart above full?
Maybe with the turbos and plumbing you need a little more oil int he crankcase to maintain stock oil pressure levels? That and the burning of oil may be part of the problem.
Good luck,
Chris
<small>[ September 27, 2002, 08:54 AM: Message edited by: Chris ARE 360 ]</small>
Maybe with the turbos and plumbing you need a little more oil int he crankcase to maintain stock oil pressure levels? That and the burning of oil may be part of the problem.
Good luck,
Chris
<small>[ September 27, 2002, 08:54 AM: Message edited by: Chris ARE 360 ]</small>
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From: Olmsted Falls, OH
Re: Low Oil Pressure, Possible Causes?? guess it's worth a shot, I'm already at 6 full quarts. That was usually enough before, but with everything flowing it way be low in the pan.
I'll try it, at least it's easier than pulling the covers again <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
I'll try it, at least it's easier than pulling the covers again <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
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From: Olmsted Falls, OH
Re: Low Oil Pressure, Possible Causes?? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Reckless:
<strong>Do you thik crankcase pressure could have anything to do with it?
Todd</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">dunno, but i'm guessing i don't have much case pressure. -10 breather line to an open K&N. Who knows <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
<strong>Do you thik crankcase pressure could have anything to do with it?
Todd</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">dunno, but i'm guessing i don't have much case pressure. -10 breather line to an open K&N. Who knows <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
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From: the moon
Re: Low Oil Pressure, Possible Causes?? I just fired mine up about 3 weeks ago.
I am using fed/mog rod bearings and the fed/mog 3/4 groove racing main bearings.
Clearance is just under .003" for both rods and mains.
The 3/4 groove mains did drop oil pressure a bit as now it is feeding the rods almost twice as long as the stockers which are less than 1/2 groove mains.
I had hot oil pressure dropping to 25psi or so at idle but would rise to about 50 at wot.
A bit low for my own taste.
I took it apart and further shimmed my oil pump relief spring.It's now shimmed .145".
Cold startup is 60+PSI.Hot idle now at 35psi and 60+psi at wot how.
By the way, if you pull the front cover and drill a hole in the oil pan lip, you can get a allen wrench to the relief spring and shim it without removing the pump <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Then just tap the hole and fit a plug in it.
I checked my factory sensor against a mechanical gage.
It reads 5psi high at idle and 5psi low at wot.
If you did not have a turbo with oiling lines I would say your bearings are bad. Loss of full load oil pressure is a symptom.
But you should not see any bearing material in your oil!
Not even a few small flakes!
Running lifters near o preload should not drop your pressure one bit.
I have done this on just about every motor I ever built.But you could rule it out by increasing the preload.
Steve
I am using fed/mog rod bearings and the fed/mog 3/4 groove racing main bearings.
Clearance is just under .003" for both rods and mains.
The 3/4 groove mains did drop oil pressure a bit as now it is feeding the rods almost twice as long as the stockers which are less than 1/2 groove mains.
I had hot oil pressure dropping to 25psi or so at idle but would rise to about 50 at wot.
A bit low for my own taste.
I took it apart and further shimmed my oil pump relief spring.It's now shimmed .145".
Cold startup is 60+PSI.Hot idle now at 35psi and 60+psi at wot how.
By the way, if you pull the front cover and drill a hole in the oil pan lip, you can get a allen wrench to the relief spring and shim it without removing the pump <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Then just tap the hole and fit a plug in it.
I checked my factory sensor against a mechanical gage.
It reads 5psi high at idle and 5psi low at wot.
If you did not have a turbo with oiling lines I would say your bearings are bad. Loss of full load oil pressure is a symptom.
But you should not see any bearing material in your oil!
Not even a few small flakes!
Running lifters near o preload should not drop your pressure one bit.
I have done this on just about every motor I ever built.But you could rule it out by increasing the preload.
Steve
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Re: Low Oil Pressure, Possible Causes?? yeah Throw in a extra quart or so. (Have it read just over a quart high.)
I have seen this when a car is a little low on oil. At WOT the oil pressure falls, coming back to normal when letting off. (This is only in a second gear blast)
Add a quart of oil (overfilled by about a quart) and the problem disappeared.
Good luck man, hope nothing bad has happened bearing wise.
Chris
I have seen this when a car is a little low on oil. At WOT the oil pressure falls, coming back to normal when letting off. (This is only in a second gear blast)
Add a quart of oil (overfilled by about a quart) and the problem disappeared.
Good luck man, hope nothing bad has happened bearing wise.
Chris
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From: Olmsted Falls, OH
Re: Low Oil Pressure, Possible Causes?? well
i've now got a .051 nitrous jet acting as an oil restrictor for the turbo feed. My smoking seems to have cleared up. And I tried adding an extra quart.
No good, actually seems worse <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
off to the shop to drop the motor <img border="0" alt="[kaboom]" title="" src="graemlins/gr_bomb.gif" />
i've now got a .051 nitrous jet acting as an oil restrictor for the turbo feed. My smoking seems to have cleared up. And I tried adding an extra quart.
No good, actually seems worse <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
off to the shop to drop the motor <img border="0" alt="[kaboom]" title="" src="graemlins/gr_bomb.gif" />
Re: Low Oil Pressure, Possible Causes?? Oh man, what a bummer! <img border="0" alt="[barf]" title="" src="graemlins/gr_barf.gif" />
I hope it is not anything too bad Matt. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
Good luck. <img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" />
I hope it is not anything too bad Matt. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
Good luck. <img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" />
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From: Centrifugal City
Re: Low Oil Pressure, Possible Causes?? Someone in the forum had a problem with the turbo mount position causing smoking oil.
I forget if the turbo was puffing or the engine, but he fixed it by changing the turbo position.
I forget if the turbo was puffing or the engine, but he fixed it by changing the turbo position.
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From: Brighton, Mi
Re: Low Oil Pressure, Possible Causes?? I had almost the exact same problem with the LS1 in my truck. I built a oil pan and pick up for it from "F" car parts. When I first put it togeather, everything was great. Then I removed the pan to modify it for a larger front differental. I replaced the "O" ring on the pick up tube because I had it apart. When I started it up, my oil pressure did the exact same thing yours is. I removed the pan to check everything. To make a long story short, the new "O" ring was smaller diameter (thinner) than the original one. The smaller size allowed the oil pump to pull air and the pressure was low. I reinstalled the original "O" ring and the pressure came right back. Both "O" rings were factory GM parts. I don't know why there is a smaller diameter one, but it caused my problem.
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From: Olmsted Falls, OH
Re: Low Oil Pressure, Possible Causes?? Not sure on the o-ring size being off, but i've got the second new one in there and the same issue. part number is legit on the o-ring, i know that.
in any case, it's about 1 hour more of work then the car lifts off the powertrain. Couldn't keep the shop owner late tonight "under penalty of wife" <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
I don't have any of the normal bad bearing noises, or even a lazy lifter noise with the oil pressure as low as it is. Piece of mind if nothing else getting into this thing. Re-bearing it, bolt it all back up, and run the snot out of it. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Before the problem got noticably worse, it was running good numbers. Should be back in action in a couple days, forseeing no major issues.
on the turbo smoke, i've got mine clocked straight. The best you can have for draining. I was just over oiling them, and the pass side has a long horizontal return hose section that was filling up a bit. Better for sure now.
more to come
in any case, it's about 1 hour more of work then the car lifts off the powertrain. Couldn't keep the shop owner late tonight "under penalty of wife" <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
I don't have any of the normal bad bearing noises, or even a lazy lifter noise with the oil pressure as low as it is. Piece of mind if nothing else getting into this thing. Re-bearing it, bolt it all back up, and run the snot out of it. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Before the problem got noticably worse, it was running good numbers. Should be back in action in a couple days, forseeing no major issues.
on the turbo smoke, i've got mine clocked straight. The best you can have for draining. I was just over oiling them, and the pass side has a long horizontal return hose section that was filling up a bit. Better for sure now.
more to come