Low oil pressure?
Thread Starter
Former Vendor
Joined: Jan 2008
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From: Surprise Arizona
Low oil pressure?
I have a 98 Vette with a built 402 and twin turbos (PTK). After changing out the oil pressure sending unit, oil pump, and even going to a heavier oil, I still only get 9psi at warm idle? The oil pressure is fine when driving.
I changed my oil recently and there was no signs of bearing failure at all. I did do a mechanical oil pressure test off the turbo feed line and it came up low. Does anyone have an idea of what it might be? Would it be wise to do another oil pressure test but in a different location?
I changed my oil recently and there was no signs of bearing failure at all. I did do a mechanical oil pressure test off the turbo feed line and it came up low. Does anyone have an idea of what it might be? Would it be wise to do another oil pressure test but in a different location?
Thread Starter
Former Vendor
Joined: Jan 2008
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From: Surprise Arizona
Tech Contributor
Joined: Jan 2007
Posts: 19,341
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From: Dyer, IN
I have a 98 Vette with a built 402 and twin turbos (PTK). After changing out the oil pressure sending unit, oil pump, and even going to a heavier oil, I still only get 9psi at warm idle? The oil pressure is fine when driving.
I changed my oil recently and there was no signs of bearing failure at all. I did do a mechanical oil pressure test off the turbo feed line and it came up low. Does anyone have an idea of what it might be? Would it be wise to do another oil pressure test but in a different location?
I changed my oil recently and there was no signs of bearing failure at all. I did do a mechanical oil pressure test off the turbo feed line and it came up low. Does anyone have an idea of what it might be? Would it be wise to do another oil pressure test but in a different location?
Team Owner
Joined: Jan 2004
Posts: 22,185
Likes: 65
From: NJ
The bearings clearances are what determine pressure in the oil system. After replacing all the the common items, Id say you may have some wear somewhere. I could be anything from cam bearings to crank bearings. Did the pressure drop all of a sudden?
Also, did you check pressure with a mechanical gauge? You could use the front port for a real quick check.
Also, did you check pressure with a mechanical gauge? You could use the front port for a real quick check.
Thread Starter
Former Vendor
Joined: Jan 2008
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From: Surprise Arizona
I bought the car the way it is. The build has about 10k miles on it. I'm not really sure the history on the car but I do have all the receipts for the car and everything that was done to it. The motor was built by Scogging Dickey (strocked LS2).
I'm not exactly sure the bearing clearences but I would image the car was fine when first built.
I'm not exactly sure the bearing clearences but I would image the car was fine when first built.
Thread Starter
Former Vendor
Joined: Jan 2008
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From: Surprise Arizona
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Burning Brakes
Joined: Aug 2006
Posts: 901
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From: Oxford PA
Couple things to check.
The usual and the biggie is the o-ring on the oil pump to make sure it did not get pinched in anyway.
And make sure the pickup tube/screen in the bottom of the oil pan is clearanced enough. And the screen is clean around the pickup inside.
If you going to check the oil pump oring again. Might as well pull the cam and scope the cam bearings to make sure one has not slid. And make sure the cam retaining plate is tight.
I ran my car with the front cover off for a couple seconds before when I was having a problem to make sure it was not coming from the cam retaining plate and to make sure oil was not coming out around the o-ring.... Not to much of a mess.
The usual and the biggie is the o-ring on the oil pump to make sure it did not get pinched in anyway.
And make sure the pickup tube/screen in the bottom of the oil pan is clearanced enough. And the screen is clean around the pickup inside.
If you going to check the oil pump oring again. Might as well pull the cam and scope the cam bearings to make sure one has not slid. And make sure the cam retaining plate is tight.
I ran my car with the front cover off for a couple seconds before when I was having a problem to make sure it was not coming from the cam retaining plate and to make sure oil was not coming out around the o-ring.... Not to much of a mess.
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
I bought the car the way it is. The build has about 10k miles on it. I'm not really sure the history on the car but I do have all the receipts for the car and everything that was done to it. The motor was built by Scogging Dickey (strocked LS2).
I'm not exactly sure the bearing clearences but I would image the car was fine when first built.
I'm not exactly sure the bearing clearences but I would image the car was fine when first built.
Thread Starter
Former Vendor
Joined: Jan 2008
Posts: 16,312
Likes: 0
From: Surprise Arizona
Couple things to check.
The usual and the biggie is the o-ring on the oil pump to make sure it did not get pinched in anyway.
And make sure the pickup tube/screen in the bottom of the oil pan is clearanced enough. And the screen is clean around the pickup inside.
If you going to check the oil pump oring again. Might as well pull the cam and scope the cam bearings to make sure one has not slid. And make sure the cam retaining plate is tight.
I ran my car with the front cover off for a couple seconds before when I was having a problem to make sure it was not coming from the cam retaining plate and to make sure oil was not coming out around the o-ring.... Not to much of a mess.
The usual and the biggie is the o-ring on the oil pump to make sure it did not get pinched in anyway.
And make sure the pickup tube/screen in the bottom of the oil pan is clearanced enough. And the screen is clean around the pickup inside.
If you going to check the oil pump oring again. Might as well pull the cam and scope the cam bearings to make sure one has not slid. And make sure the cam retaining plate is tight.
I ran my car with the front cover off for a couple seconds before when I was having a problem to make sure it was not coming from the cam retaining plate and to make sure oil was not coming out around the o-ring.... Not to much of a mess.
Tech Contributor
Joined: Jan 2007
Posts: 19,341
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From: Dyer, IN
Ok, so you have no idea what you are chasing here...which sucks. Did the original owner say the oil pressure was always low, or is that the reason he sold the car? If it was that way from day one..who knows...maybe bearing clearances...oil galley plug, etc.
Thread Starter
Former Vendor
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From: Surprise Arizona
The car was in storage for six months before it was sold to the second owner. The new owner only put 200 miles on the car before selling it to me.
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
I bought the car off the guy who purchased it from the original owner. The car was sold because the current owner didn't know what was wrong with it. I purchased the car because I got it for a really good price due to the issue it's having. I've talked to the original owner once and he said it didn't have that problem when he owned it.
The car was in storage for six months before it was sold to the second owner. The new owner only put 200 miles on the car before selling it to me.
The car was in storage for six months before it was sold to the second owner. The new owner only put 200 miles on the car before selling it to me.
Thread Starter
Former Vendor
Joined: Jan 2008
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From: Surprise Arizona
Thanks for the explanation. For future, it's a good idea to give full disclosure in your first post, so everyone doesn't throw the obvious fixes at you (which it seems you've already attempted anyway). Unless you get some super words of wisdom, something tells me you'll be tearing into the motor. Good luck.
Le Mans Master
Joined: Jun 2004
Posts: 6,164
Likes: 103
i would try a mechanical gauge, maybe something wrong with the factory digital/analog gauge. 9psi sounds like the engine would have blown up by now or atleast rod knock or something. take the oil filter off put a pan under it and let it rip, watch to see how fast it's coming out and check for something blocking the filter area. twin turbo oil lines cloged or maybe forigen debris from the turbos blocking an oil passage somewhere
Last edited by 1320IN9; Sep 28, 2009 at 11:48 PM. Reason: change
Tech Contributor
Joined: Jan 2007
Posts: 19,341
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From: Dyer, IN
Great troubleshooting technique for an engine with a low idle oil pressure issue...take the filter off, and start her up.....so the oil pressure drops to zero...
Last edited by lucky131969; Sep 29, 2009 at 12:08 AM.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
Sounds like an internal oil leak to me. By chance did you check the oil galley plug on the driver side front of the engine when you changed the oil pump? When you get the engine apart, check the dumbell in the back and the cam plate and pressure check the oil pickup tube to make sure it hasn't been compromised in any way. You may also want to create an external pump and make a block off plate for the existing oil pump and try pumping oil into the side of the block with the engine apart and see if you can identify the internal oil leak. I'm sure you'll find it before you have to take it that far though.
Thread Starter
Former Vendor
Joined: Jan 2008
Posts: 16,312
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From: Surprise Arizona
Sounds like an internal oil leak to me. By chance did you check the oil galley plug on the driver side front of the engine when you changed the oil pump? When you get the engine apart, check the dumbell in the back and the cam plate and pressure check the oil pickup tube to make sure it hasn't been compromised in any way. You may also want to create an external pump and make a block off plate for the existing oil pump and try pumping oil into the side of the block with the engine apart and see if you can identify the internal oil leak. I'm sure you'll find it before you have to take it that far though.
The oil pressure is fine under throttle. I'm only seeing low oil pressure at warm idle. I had the car on the highway the other day and I was getting 30psi cruising at 70 in 5th.