Oil Pressure Bleeding Off at Idle
Oil Pressure Bleeding Off at Idle Here's my issue. I have a 2000 LS1 with now 88K on it. 10K ago a Cam Motion 224/228 .585/.585 114 cam, Comp 921 spring kit, and Comp standard length pushrods, and ported LS1 oil pump from TSP were installed. Upon intitial start-up it was found that the engine was not holding oil pressure when it came up to operating temp. With the engine hot the pressure would bleed down to 20-22psi but then when the engine was brought off idle the oil pressue would return to 40psi minimum. The shop who did the work contacted Allen Futural who reccomended the use of 20w-50 due to the low pressure and likely opened clearances due to the age and mileage on the engine. The heavier oil relieved a majority of the problem. With the low oil pressure the stock lifters began to collapse at idle and tick. So recienly I purchased the new Crane lifters part # 144535-16 which are equal to the Morel lifters. This was supposed to cure my lifter collapse problem. However, after the engine has been run for about an hour and is hot the oil pressure bleeds off to what the gauge indicates is 20-22psi and the tick come back which I assume to be the lifters as it sounds the same as it did with the stock lifters. It has been suggested that my engine may have clearance issues in the bottom end which allows oil pressure to bleed off causing my problem. When the engine was stock the oil pressure would regularlly operate between 25-45psi which is how it was when I purchased the car with 60k on it. Any experience or insightful input is greatly appreciated.
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Joined: Mar 2004
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From: Laguna Niguel, CA
Are you saying that when you first had the car, stock, it would idle hot at 25PSI and then raise to 40 off idle?
Or it only had a oil pressure problem after taking the stock cam out.
If the oil pressure has only dropped since you changed the came, then most likely it is a pinched oil pickup tube o-ring.
Or it only had a oil pressure problem after taking the stock cam out.
If the oil pressure has only dropped since you changed the came, then most likely it is a pinched oil pickup tube o-ring.
The low oil pressure stock (hot) was 25psi and then off idle would go to 40-50psi. Beacuse this lower than normal pressure occured prior to the cam swap and any other internal modification I do not believe it to be related to an o-ring. As I said I purchased the car with 60K and it was all stock. I thought the pressure looked low when I first got the car and I checked it according to the GM Service manual and at the specified RPM the oil pressure was within spec. The problem occurs at idle only without any drivability or performance issues.
Now lets make it more complex.
The oil pressure at idle will drop as indicated by the factory gauge when the car is hot as said before. However if the car is facing up an incline such as a hill or bridge and is stopped at idle the pressure will drop faster than it would had the car been on a level surface. Also if the car is stopped at idle in a left bank (driver's side sitting lower in the turn than the passenger) of appox. 5 degrees or greater the oil pressure will again drop faster than it would had the car been on a level surface.
Now when the car is facing downward or in a right bank the oil pressure takes longer to drop off than had it been level. Meaning the pressure stays higher longer at idle if the car is facing down (negative angle of attack) or in a right bank.
This it me is the very confusing part again leading me away from something as simple as an o-ring.
The oil pressure at idle will drop as indicated by the factory gauge when the car is hot as said before. However if the car is facing up an incline such as a hill or bridge and is stopped at idle the pressure will drop faster than it would had the car been on a level surface. Also if the car is stopped at idle in a left bank (driver's side sitting lower in the turn than the passenger) of appox. 5 degrees or greater the oil pressure will again drop faster than it would had the car been on a level surface.
Now when the car is facing downward or in a right bank the oil pressure takes longer to drop off than had it been level. Meaning the pressure stays higher longer at idle if the car is facing down (negative angle of attack) or in a right bank.
This it me is the very confusing part again leading me away from something as simple as an o-ring.
Originally Posted by LSWon00
Now lets make it more complex.
The oil pressure at idle will drop as indicated by the factory gauge when the car is hot as said before. However if the car is facing up an incline such as a hill or bridge and is stopped at idle the pressure will drop faster than it would had the car been on a level surface. Also if the car is stopped at idle in a left bank (driver's side sitting lower in the turn than the passenger) of appox. 5 degrees or greater the oil pressure will again drop faster than it would had the car been on a level surface.
Now when the car is facing downward or in a right bank the oil pressure takes longer to drop off than had it been level. Meaning the pressure stays higher longer at idle if the car is facing down (negative angle of attack) or in a right bank.
This it me is the very confusing part again leading me away from something as simple as an o-ring.
The oil pressure at idle will drop as indicated by the factory gauge when the car is hot as said before. However if the car is facing up an incline such as a hill or bridge and is stopped at idle the pressure will drop faster than it would had the car been on a level surface. Also if the car is stopped at idle in a left bank (driver's side sitting lower in the turn than the passenger) of appox. 5 degrees or greater the oil pressure will again drop faster than it would had the car been on a level surface.
Now when the car is facing downward or in a right bank the oil pressure takes longer to drop off than had it been level. Meaning the pressure stays higher longer at idle if the car is facing down (negative angle of attack) or in a right bank.
This it me is the very confusing part again leading me away from something as simple as an o-ring.
All of what you just said leads me to be more inclined that it is the O-ring. It sounds as if when you have maximum oil level at the Pick-up, you get better oil pressure. Get a book on pump theory, you will understand...
Hammer
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See that is why I asked. So would you reccomend going with a new pump as well? I have to change the oil pan gasket so I think I will do the pump and o-ring then and possible the pickup.
If so I'm looking at the Melling pump and getting it ported depending upon the reccomendation of Thunder Racing.
If so I'm looking at the Melling pump and getting it ported depending upon the reccomendation of Thunder Racing.
Last edited by LSWon00; Jan 16, 2007 at 08:56 PM.
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