So confused with this low oil pressure?
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So confused with this low oil pressure? So I have a LH6 motor, that I ended up having a AFM delete done to. Ended up replacing rod bearings, camshaft bearings, piston rings, camshaft, rockers, pushrods, water pump, oil pump, and all the new gaskets. Ended up being more of an ordeal than expected, I had a friend who is a chevy tech do all the work.
He ended up pulling the motor, found out it had a ton of bearing material in the oil (camshaft bearings), so he said he cleaned the **** out of the block and put everything back together. Its running very well now, BUT. I'm having low oil pressure problems.
Btw I replaced the pump with a new melling 10355 high volume pump. Along with the inlet and ring I believe. My tech is also confused, and thought it was because I got a standard volume pump, but I didnt.
ALSO, it seems to be consuming oil in some way, and I'm not understanding why that is either. I put 6 qts in when I changed the oil after it was put back together (had some metallic material, but idk if that's from all the new components or what) but I went probably 100 miles, and I put in a quart.
The oil pressure when on a cold start is perfectly fine. Right above 40 on the gauge. But when it is warmed up, it just continues to slowly drop the warmer it gets. It got down to 5 psi according to my Torque pro app on 5W-30. When I changed it, I got 10W-40 and it usually stay between 9-10 psi.
But what I'm trying to figure out is if I should just call it quits with this Envoy and try selling it and getting a different vehicle. I feel like I should keep it at this point, but im afraid of this thing having more problems after the pump.
I'd like to hear you guys' opinions on this, because after damn near rebuilding the motor and still having problems is frustrating the crap out of me. Plus its making me broke.
He ended up pulling the motor, found out it had a ton of bearing material in the oil (camshaft bearings), so he said he cleaned the **** out of the block and put everything back together. Its running very well now, BUT. I'm having low oil pressure problems.
Btw I replaced the pump with a new melling 10355 high volume pump. Along with the inlet and ring I believe. My tech is also confused, and thought it was because I got a standard volume pump, but I didnt.
ALSO, it seems to be consuming oil in some way, and I'm not understanding why that is either. I put 6 qts in when I changed the oil after it was put back together (had some metallic material, but idk if that's from all the new components or what) but I went probably 100 miles, and I put in a quart.
The oil pressure when on a cold start is perfectly fine. Right above 40 on the gauge. But when it is warmed up, it just continues to slowly drop the warmer it gets. It got down to 5 psi according to my Torque pro app on 5W-30. When I changed it, I got 10W-40 and it usually stay between 9-10 psi.
But what I'm trying to figure out is if I should just call it quits with this Envoy and try selling it and getting a different vehicle. I feel like I should keep it at this point, but im afraid of this thing having more problems after the pump.
I'd like to hear you guys' opinions on this, because after damn near rebuilding the motor and still having problems is frustrating the crap out of me. Plus its making me broke.
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Bump.
Any advice on possible causes of this low oil pressure would be AMAZING. After realizing I'm going to get about half of what I have in this on a trade in, I'm kind of thinking just keep it.
I just really want to resolve this issue. Since the cam and rod bearings are new, they shouldn't be the problem. I'm just really afraid its the main bearings. Because that means the cranks gone. But I don't know what else itd be.
If I had to spend the money to get a new crank and everything associated. I almost want to just find a LY6 or L96 (6.0L motor) on eBay and drop it in. From what I have read, it can work. I already have AFM tuned out of my ECM. And ive also heard you could just leave the VVT connector unplugged, and all is good. Is this true?
This LH6 of mine is just driving me crazy. The oil consuming and low oil pressure make me afraid to put a penny more into it. But I'm also afraid of buying a used motor aswell. Even tho a lot of the eBay sellers have 30 day returns, and 90 day warranties on the main engine components.
Any advice on possible causes of this low oil pressure would be AMAZING. After realizing I'm going to get about half of what I have in this on a trade in, I'm kind of thinking just keep it.
I just really want to resolve this issue. Since the cam and rod bearings are new, they shouldn't be the problem. I'm just really afraid its the main bearings. Because that means the cranks gone. But I don't know what else itd be.
If I had to spend the money to get a new crank and everything associated. I almost want to just find a LY6 or L96 (6.0L motor) on eBay and drop it in. From what I have read, it can work. I already have AFM tuned out of my ECM. And ive also heard you could just leave the VVT connector unplugged, and all is good. Is this true?
This LH6 of mine is just driving me crazy. The oil consuming and low oil pressure make me afraid to put a penny more into it. But I'm also afraid of buying a used motor aswell. Even tho a lot of the eBay sellers have 30 day returns, and 90 day warranties on the main engine components.
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Hi Dingo,
You mentioned that you've already replaced some big items on the LH6 motor of yours:
"rod bearings, camshaft bearings, piston rings, camshaft, rockers, pushrods, water pump, oil pump, and all the new gaskets"
No reason to let go all of that just for a used motor that you don't know the proper history of. I'm surprised that the main bearings weren't inspected, given the extensive make-over/repair work already done. I'd say, since you've already done this much work, that you take it one step further and continue:
1) Use a mechanical gauge instead
Even if your main bearings ARE indeed bad, I'd expected a very high flow pump like a 10355 to give you plenty of pressure.
2) Someone correct me if I'm wrong here, and I'm not as familiar with an LH6 engine, but a 10355 pump is OVER-kill. Your oil being consumed/losing oil could be from excessive oil pump pressure finding its' way in to the combustion chamber.
Edit: AFM - got it. It requires a higher flow pump. So perhaps not over-kill.
Does the engine show any signs/symptoms of actual malfunction? Smoke out the exhaust perhaps?
Are your spark plugs covered in oil? (the threads)
What's the operating temperature? I assume it's not overheating.
Thanks,
Andy
You mentioned that you've already replaced some big items on the LH6 motor of yours:
"rod bearings, camshaft bearings, piston rings, camshaft, rockers, pushrods, water pump, oil pump, and all the new gaskets"
No reason to let go all of that just for a used motor that you don't know the proper history of. I'm surprised that the main bearings weren't inspected, given the extensive make-over/repair work already done. I'd say, since you've already done this much work, that you take it one step further and continue:
1) Use a mechanical gauge instead
Even if your main bearings ARE indeed bad, I'd expected a very high flow pump like a 10355 to give you plenty of pressure.
2) Someone correct me if I'm wrong here, and I'm not as familiar with an LH6 engine, but a 10355 pump is OVER-kill. Your oil being consumed/losing oil could be from excessive oil pump pressure finding its' way in to the combustion chamber.
Edit: AFM - got it. It requires a higher flow pump. So perhaps not over-kill.
Does the engine show any signs/symptoms of actual malfunction? Smoke out the exhaust perhaps?
Are your spark plugs covered in oil? (the threads)
What's the operating temperature? I assume it's not overheating.
Thanks,
Andy
Last edited by AndyTA; Nov 12, 2018 at 03:42 PM.
Pull the oil pressure sensor and see if theres a screen filter in the block. If this becomes restricted it can cause weird pressure readings. A real low oil pressure coils also be caused by the oil pump pickup o ring being installed incorrectly and/or oil pump internal pressure relief valve stuck open. If you werent having oil pressure problems before, I would guess its one of these things causing the problem now.
As for oil consumption, was it doing this before the new parts? If not, the new HV oil pump could be causing more oil to get sucked in the intake manifold. Are you getting any misfires CELs?
As for oil consumption, was it doing this before the new parts? If not, the new HV oil pump could be causing more oil to get sucked in the intake manifold. Are you getting any misfires CELs?
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I know if you forget to but the barbell or the oil galley plug by the oil pump it can cause low oil pressure. With all the cleaning the tech did i would think he would remove these and clean the galley. Maybe he forgot to put em back in or the oil galley plug popped out once it was running.
If the barbell is removed, youll see very low pressure. Most of the oil will just get pumped against the rear cover and right back into the pan. Thats what the o-ring part of the barbell does. It keeps the gallery sealed, and directs the oil up toward the sender, cam bearings, lifters, etc. Its happened many times, with several threads on here giving the details of a low oil pressure situation.
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Im basing my ideas off of experience with large diesel engines here. We see this alot after a rebuild. It is usually a plug not installed or a crank that has been machined and the tech installs standard bearings on it. I know this isnt a diesel engine but the symtom is exactly the same. Oil pressure at idle cold even if it is the lower spectrum then dropping to 0 as it warms up. And no the extra clearnace usually isnt all that extra noisy. With him having a high volume pump i think it could make pressure when cold even with the plug or barbell out. But im basing this off of my experience with different kinds of engines so im sure im wrong and it is possible for the things i said to cause it. I defer to those that know this engine better then i. Sorry to mislead the OP.
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If the barbell is removed, youll see very low pressure. Most of the oil will just get pumped against the rear cover and right back into the pan. Thats what the o-ring part of the barbell does. It keeps the gallery sealed, and directs the oil up toward the sender, cam bearings, lifters, etc. Its happened many times, with several threads on here giving the details of a low oil pressure situation.
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Pull the oil pressure sensor and see if theres a screen filter in the block. If this becomes restricted it can cause weird pressure readings. A real low oil pressure coils also be caused by the oil pump pickup o ring being installed incorrectly and/or oil pump internal pressure relief valve stuck open. If you werent having oil pressure problems before, I would guess its one of these things causing the problem now.
As for oil consumption, was it doing this before the new parts? If not, the new HV oil pump could be causing more oil to get sucked in the intake manifold. Are you getting any misfires CELs?
As for oil consumption, was it doing this before the new parts? If not, the new HV oil pump could be causing more oil to get sucked in the intake manifold. Are you getting any misfires CELs?
I was planning on going back into the oil pan and putting a new pump in, but I actually contacted Melling asking about it and they basically gave me the answer of "Oil pumps either work, or they don't" so I doubt it actually is the pump. But the O-ring could still be suspect.
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Hi Dingo,
You mentioned that you've already replaced some big items on the LH6 motor of yours:
"rod bearings, camshaft bearings, piston rings, camshaft, rockers, pushrods, water pump, oil pump, and all the new gaskets"
No reason to let go all of that just for a used motor that you don't know the proper history of. I'm surprised that the main bearings weren't inspected, given the extensive make-over/repair work already done. I'd say, since you've already done this much work, that you take it one step further and continue:
1) Use a mechanical gauge instead
Even if your main bearings ARE indeed bad, I'd expected a very high flow pump like a 10355 to give you plenty of pressure.
2) Someone correct me if I'm wrong here, and I'm not as familiar with an LH6 engine, but a 10355 pump is OVER-kill. Your oil being consumed/losing oil could be from excessive oil pump pressure finding its' way in to the combustion chamber.
Edit: AFM - got it. It requires a higher flow pump. So perhaps not over-kill.
Does the engine show any signs/symptoms of actual malfunction? Smoke out the exhaust perhaps?
Are your spark plugs covered in oil? (the threads)
What's the operating temperature? I assume it's not overheating.
Thanks,
Andy
You mentioned that you've already replaced some big items on the LH6 motor of yours:
"rod bearings, camshaft bearings, piston rings, camshaft, rockers, pushrods, water pump, oil pump, and all the new gaskets"
No reason to let go all of that just for a used motor that you don't know the proper history of. I'm surprised that the main bearings weren't inspected, given the extensive make-over/repair work already done. I'd say, since you've already done this much work, that you take it one step further and continue:
1) Use a mechanical gauge instead
Even if your main bearings ARE indeed bad, I'd expected a very high flow pump like a 10355 to give you plenty of pressure.
2) Someone correct me if I'm wrong here, and I'm not as familiar with an LH6 engine, but a 10355 pump is OVER-kill. Your oil being consumed/losing oil could be from excessive oil pump pressure finding its' way in to the combustion chamber.
Edit: AFM - got it. It requires a higher flow pump. So perhaps not over-kill.
Does the engine show any signs/symptoms of actual malfunction? Smoke out the exhaust perhaps?
Are your spark plugs covered in oil? (the threads)
What's the operating temperature? I assume it's not overheating.
Thanks,
Andy
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I'll also ask my tech about the barbell thing. Also, the crank thing scares me because the crank that was in this motor is either newer or has been machined. My tech showed me a picture, and the crank was pretty shiny while the rods were oil-stained. That's what worried him, and me in the beginning for the AFM delete. He said the crank felt and looked good, so he didn't open it. He did also say that the rod bearings were untorqued. Like some would be tight, and others really loose. He said there weren't any wear on the crank-to-rod part. So we just got new bolts, and rod bearings.
Also, after hearing from Melling the things they suggested to look at it the main bearings and they also said the lifter bores. Haven't heard anything about the lifter bores.
Also, as for oil pressure relief. Not sure where the hell that is in this motor. Tech said it wasn't in the pan, and when I changed my oil last time, I didn't see that little spot inside the filter housing either.
Also, after hearing from Melling the things they suggested to look at it the main bearings and they also said the lifter bores. Haven't heard anything about the lifter bores.
Also, as for oil pressure relief. Not sure where the hell that is in this motor. Tech said it wasn't in the pan, and when I changed my oil last time, I didn't see that little spot inside the filter housing either.
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See the thing I'm worried about tho is, will the things I have replaced be destroyed by the time I put a new crank in? Assuming that's even what it is. I feel like the exhaust smells slightly oily, but I'm not sure. No smoke tho, can't even really tell currently since it's so cold lol.
I'm not sure anyone will really be able to answer that accurately. I still feel strongly about you finding a different method of reading oil pressure, rather than through an app?
Check your spark plugs - all of them. Get a proper read on them using a chart, and check for oil on the threads. This is to help figure out where you're burning/losing oil.
I know this will sound silly because you just got done putting the engine back together, but have you considered doing a thorough leak down test to listen for where air escapes/leak down percentages? Edit: The reason I mention this is because of your concern about prematurely wearing other parts away because of the supposed low oil pressure. This will be a good way to check the health of the engine in its' current state - but that depends on how many miles you've put on it since all of this has been done.
I'd also wanna throw my vote in the "check all o-rings again" hat.
Start with confirming the oil pressure reading is correct/accurate. Hook up a mechanical gauge and confirm. From there... how was the AFM deleted, lots of threads about low pressure after the delete. It's recommended to tap/thread/plug the towers or use rivets to plug them off. I still don't see why just running a non AFM cover with seals doesn't do the trick but supposedly that's not enough. PM tech@ws6store on here, he knows a lot about the AFM delete and oil pressure woes.
But you're using a lot of oil, that makes me think you have ring seal issues.
That's all very applicable, you weren't misleading or off base there.
But you're using a lot of oil, that makes me think you have ring seal issues.
Im basing my ideas off of experience with large diesel engines here. We see this alot after a rebuild. It is usually a plug not installed or a crank that has been machined and the tech installs standard bearings on it. I know this isnt a diesel engine but the symtom is exactly the same. Oil pressure at idle cold even if it is the lower spectrum then dropping to 0 as it warms up. And no the extra clearnac
e usually isnt all that extra noisy. With him having a high volume pump i think it could make pressure when cold even with the plug or barbell out. But im basing this off of my experience with different kinds of engines so im sure im wrong and it is possible for the things i said to cause it. I defer to those that know this engine better then i. Sorry to mislead the OP.
e usually isnt all that extra noisy. With him having a high volume pump i think it could make pressure when cold even with the plug or barbell out. But im basing this off of my experience with different kinds of engines so im sure im wrong and it is possible for the things i said to cause it. I defer to those that know this engine better then i. Sorry to mislead the OP.
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If the cam bearings were replaced they have to be checked they are the correct sizes to match cam journals. Its not just a simple put cam bearings in and hope they are sized right. Its the 1st thing I'd go back in and check.
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Start with confirming the oil pressure reading is correct/accurate. Hook up a mechanical gauge and confirm. From there... how was the AFM deleted, lots of threads about low pressure after the delete. It's recommended to tap/thread/plug the towers or use rivets to plug them off. I still don't see why just running a non AFM cover with seals doesn't do the trick but supposedly that's not enough. PM tech@ws6store on here, he knows a lot about the AFM delete and oil pressure woes.
But you're using a lot of oil, that makes me think you have ring seal issues.
That's all very applicable, you weren't misleading or off base there.
But you're using a lot of oil, that makes me think you have ring seal issues.
That's all very applicable, you weren't misleading or off base there.
And as far as the oil burning, idk man. He does this **** for a living so I don't see how he'd mess that part up. Because we put new rings in it. He said the old ones looked fine, but I replaced them anyways.
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I didn't know the cam bearings had size differences, and he just told me to make sure I got the right rod bearings since they were .01 I believe. But when I looked on Napa ordering the parts, I don't remember even seeing different cam bearings. They had tons of options for the rod bearings tho. Also, if it would be the cam bearings, do you think the cam will survive? My tech said the cam bearings were literally completely worn out when he took it apart. There was barely any material of the bearing left.
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Btw, I'm a car detailer at this dealership so communication is good with my tech. He said one of the other techs I think buys and sells ls engines. We were originally thinking about just doing that (wish I did at this point) but he only had a 4.8 at that time, and I didn't really wanna go down in torque. I feel like at this point I should just try to find another ls and plop it in, and take this engine apart and build it. Because I kind of want to build a drift car once I have some money, and I do want to build something.
It's just sketchy tho, but I could end up finding a healthy engine tho also.
ALSO, does anyone know if there would be a secondary signal? Or is the reading the sensor gets what goes straight on the gauge. Trying to rule out electrical issues first, but I'm not very good at understanding wiring honestly.
It's just sketchy tho, but I could end up finding a healthy engine tho also.
ALSO, does anyone know if there would be a secondary signal? Or is the reading the sensor gets what goes straight on the gauge. Trying to rule out electrical issues first, but I'm not very good at understanding wiring honestly.