Hey everyone. I have a 2008 Sierra with 5.3. Had an AFM lifter failure about a month ago. Decided to do complete tear down and rebuild motor. Had bottom end done by local shop. Had a Stage 2 cam from TSP and DoD delete kit along with new oil pump springs and lifters installed. Had truck dyno tuned. So i am having a oil pressure issue. Starts up at 40 plus and even up to 60 while cold. Once warmed up pressure drops. Runs 40 on highway and 20 at idle. I removed lower pressure relief valve from oil pan. Put a good oil filter in and using 5w30 oil. Ive done compression checks. As for the clogged filter on the pressure switch on valley plate, I did not know about this until after installed back in truck but after speaking with Texas Speed they stated their valley plate does not have a filter. But with new motor wouldnt think it be clogged anyways. No other indications of issues.
Low Oil Pressure at Idle
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Brettahelm
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Mine is not technically stock. I have the AFM delete kit installed. I should have done it myself but I didn't have the time so I took it to a trusted shop to have them do it. He installed the high flow oil pump and told me to watch the pressure, if it goes below 20psi I need to look at have the bottom end rebuilt. I'm just concerned that it running at 17-18 psi it would start causing damage.
I did a delete last month myself, had 2 orings in the "new seals" kit, both will fit but only 1 was tight around the oil pickup tube and oil pump, I would want to see that if it were me. Good luck! I'm 22 to 25 psi warm idle, and 40ish when accelerating.
Has anyone figured this issue out? I just had my engine rebuilt because of the afm lifters collapsing. Stage 2 cam, melting oil pump, new cam and crank bearings, all new gaskets.
Oil pressure was around 20 psi in the first 50 miles of engine break-in. I changed the oil last night and it's around 35 psi now but slowly going back to 20 ish.
Engine runs fine except choppy idle but I have spent so much money I need to know if any one has fixed this issue.
Oil pressure was around 20 psi in the first 50 miles of engine break-in. I changed the oil last night and it's around 35 psi now but slowly going back to 20 ish.
Engine runs fine except choppy idle but I have spent so much money I need to know if any one has fixed this issue.
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Did you pay a shop to do the rebuild or do it yourself?
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Ok. Understood. Have you reached out to them on this low pressure condition? That would be my first path.
I have reached out to shop and apparently he doesn't warranty his work. We had a very heated conversation and I noticed oil leak behind the harmonic balancer. Which may be my issue with low oil pressure and rough idle.
Now I wish I would have went to a reputable shop.
Has anyone else come up with fixes yet?
Now I wish I would have went to a reputable shop.
Has anyone else come up with fixes yet?
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18,470 Posts
I bet that was a heated conversation. I would not have anything done at a shop with no warranty. And if I have the time...I will always try and do the repairs myself.
There is a seal on the timing chain cover where the crank shaft goes through. A lot of stuff to pull off just to get to it...but just takes some time. Pulling off the crank pulley is the worst of it really. But that will not cause low pressure.
There is a seal on the timing chain cover where the crank shaft goes through. A lot of stuff to pull off just to get to it...but just takes some time. Pulling off the crank pulley is the worst of it really. But that will not cause low pressure.
Would like to bring this alive again......any updates. I am fighting low pressure at idle, HOT 18-20.2012 5.3 changed o-ring,pump screen and sending unit. Manual test is 32 at filter, 18 at sending unit. Was thinking about shimming oil pump relief spring.
So what did you come up with? End result?
So what did you come up with? End result?
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So let's talk about LS oil pressure issues. Typically what kills the oil pressure in this line of engines is the cam bearings. The OP said the bottom end was rebuilt. My question is if the cam bearings were replaced. If they were it could actually cause issues. Before everyone goes nuts let me explain this. It was explained to me that the LS series of engines do not have aligned cam bearings journals. Instead the bearings are undersized when installed in the block during manufacturing and are then align bored. This in theory creates the most accurate front to back alignment in a mass production situations. So installing a new cam bearing or bearings may create a wear issue that could lead to large oil clearance issues. I was always told that an LS with cam bearing issues is no longer a good candidate for repair. My question is did the company that built this motor know this. The service bearings from GM are polymer coated and my thought is that can wear off fast and easy to compensate for the journal misalignment. Problem is that opens tolerances. Even GM allows for more oil tolerance on replacement bearings. You may be stuck with what you have as align boring the cam bearings is a manufacturer only capability. I'll look into this further but I'm almost positive that's the dirty little secret of the LS engines. Cam bearing issues lead to block replacement.
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After further review. The 5 cam bearing journals are 3 different sizes. The front and the back are the largest. The center journal is the smallest and the two others are intermediate in size. They all have the same inside diameter. That would make the traditional method of aligning the journals impossible to do. That's why they
I did throw some 5w-40 in it to try. Mobil 212 filter. Hot idle 22psi. Given 220000 km I like it. I will switch back to 5w30 next oil change see the difference. Dont think I am hurting anything with the 5w40 with the miles on truck eh? Probably best thing I did for it I am thinking? HAHA
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Increasing the weight of an oil means it does not flow as well as the lighter weight oil. This may give you the higher pressure showing up on a gauge...but it is not helping to get oil to the critical bearings. In fact it is making the problem worse. I would not recommend doing this and suggest running the weight of oil recommended by the manufacturer.
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MY truck runs roughly 18-20 hot idle. I'm at 118k miles btw and my truck runs great.
I was talking to my mechanic that seems to know these motors quite a bit.
He looked it up on his laptop and he said 18-20 hot idle is normal for these Trucks
Wish i had taken a screen shot of his laptop
let me say this again; 18-20 hot idle is normal for these Trucks
Thats what he said
Discuss
I was talking to my mechanic that seems to know these motors quite a bit.
He looked it up on his laptop and he said 18-20 hot idle is normal for these Trucks
Wish i had taken a screen shot of his laptop
let me say this again; 18-20 hot idle is normal for these Trucks
Thats what he said
Discuss
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