oil pressure issue, pics of teardown, what was the cause?
05-11-2013, 02:52 PM
#1
oil pressure issue, pics of teardown, what was the cause? This is a continuation of this thread: https://ls1tech.com/forums/generatio...hen-reuse.html
I have since removed the engine from the car and taken it halfway apart, to examine the bearings, crank, and cam.
HISTORY: 04 LS6 obtained 5 years ago as a zero mile rebuild with a new LS6 oil pump. Put it into my truck as a replacement for the stock 6.0 (which also died of oiling issues oddly enough). Ran the LS6 in the truck for 4 years and 33k miles, always made 45-70psi oil pressure. Had castrol synthetic 5-30 run in it since the first 500 miles.
Last year I pulled the LS6 out of the truck and swapped it into my 85 corvette. The only thing I changed was the cam, I put a TSP torquerv2 cam in, along with their springs and pushrods. Start the vette up with the LS6 and I still get 45psi at hot idle and 65+ driving.
Send the car to get street tuned and the guy calls me when he's almost there from the interstate to tell me he's seeing reduced oil pressure of about 35 on the highway. He put a mechanical gauge on when he got to the shop which indicated 25 at hot idle and 35-40 revving.
I get the car back and remove the motor and tear it halfway apart. A few of the bearings look a little rougher than I'd expect, but I don't see any catastrophic failure that would cause the loss of oil pressure.
The cam looks as good as it did when it went in:
I can see no significant problems with the cam bearings. There are a few nicks here and there from cam remove/install, but they are not deep at all. None have spun, I can confirm that all the oiling holes are aligned as they should be.
Rod 8:
Rod 7:
Rod 6:
Rod 5:
Rod 1:
Rod 2:
Rod 4:
Rod 3:
Main 1:
Main 2:
Main 3:
Main 4:
Main 5:
I have since removed the engine from the car and taken it halfway apart, to examine the bearings, crank, and cam.
HISTORY: 04 LS6 obtained 5 years ago as a zero mile rebuild with a new LS6 oil pump. Put it into my truck as a replacement for the stock 6.0 (which also died of oiling issues oddly enough). Ran the LS6 in the truck for 4 years and 33k miles, always made 45-70psi oil pressure. Had castrol synthetic 5-30 run in it since the first 500 miles.
Last year I pulled the LS6 out of the truck and swapped it into my 85 corvette. The only thing I changed was the cam, I put a TSP torquerv2 cam in, along with their springs and pushrods. Start the vette up with the LS6 and I still get 45psi at hot idle and 65+ driving.
Send the car to get street tuned and the guy calls me when he's almost there from the interstate to tell me he's seeing reduced oil pressure of about 35 on the highway. He put a mechanical gauge on when he got to the shop which indicated 25 at hot idle and 35-40 revving.
I get the car back and remove the motor and tear it halfway apart. A few of the bearings look a little rougher than I'd expect, but I don't see any catastrophic failure that would cause the loss of oil pressure.
The cam looks as good as it did when it went in:
I can see no significant problems with the cam bearings. There are a few nicks here and there from cam remove/install, but they are not deep at all. None have spun, I can confirm that all the oiling holes are aligned as they should be.
Rod 8:
Rod 7:
Rod 6:
Rod 5:
Rod 1:
Rod 2:
Rod 4:
Rod 3:
Main 1:
Main 2:
Main 3:
Main 4:
Main 5:
05-11-2013, 03:02 PM
#3
QUESTIONS:
1) I do not see a catastrophic oiling failure here which would cause a sudden loss of oil pressure. While some of the bearings do not look great, I do not see any that spun or are showing copper. Is it normal for bearings that do not look terrible to exhibit low oil pressure suddenly?
2) It goes without saying that since I am this far in, I will go ahead and replace all the bearings. Can the rods and pistons be left in the engine when this is done? (I know you think that's a halfass way to do it, and I'll explain why I want to do this below).
3) I had installed ARP rod bolts in this engine years ago. I do not see any flat spots on the rod bearings that would indicate an ovaled rod bore, which is what some people claim happens when ARP bolts are used. With this in mind, I should not need to remove the rods and have them re-bored, correct? Again, I want to try and avoid removing the pistons and heads to get the rods out.
So you say, why don't you take the heads off it and put new rings in too, go ahead and do a total rebuild now?
Well, I was told when I got this motor that the heads had already been milled 0.030". I don't know what the practical limit for milling these heads is, but that has to be getting close. So if I pull them again, this could cause me problems with milling them again, possibly cause issues with PTV clearance, and also pushrod length may have to be changed again, right? So I'd rather leave that part of it alone if at all possible.
1) I do not see a catastrophic oiling failure here which would cause a sudden loss of oil pressure. While some of the bearings do not look great, I do not see any that spun or are showing copper. Is it normal for bearings that do not look terrible to exhibit low oil pressure suddenly?
2) It goes without saying that since I am this far in, I will go ahead and replace all the bearings. Can the rods and pistons be left in the engine when this is done? (I know you think that's a halfass way to do it, and I'll explain why I want to do this below).
3) I had installed ARP rod bolts in this engine years ago. I do not see any flat spots on the rod bearings that would indicate an ovaled rod bore, which is what some people claim happens when ARP bolts are used. With this in mind, I should not need to remove the rods and have them re-bored, correct? Again, I want to try and avoid removing the pistons and heads to get the rods out.
So you say, why don't you take the heads off it and put new rings in too, go ahead and do a total rebuild now?
Well, I was told when I got this motor that the heads had already been milled 0.030". I don't know what the practical limit for milling these heads is, but that has to be getting close. So if I pull them again, this could cause me problems with milling them again, possibly cause issues with PTV clearance, and also pushrod length may have to be changed again, right? So I'd rather leave that part of it alone if at all possible.
05-11-2013, 03:18 PM
#4
There's a right way, a wrong way, and a half azz way to building engines...The choice is yours... Honestly...don't throw out there that ARP rod bolts will live in an engine without re-sizing, resizing is the "right" way to do it. It may be ok in your engine, but not ok in another. Beside, your having issues with your engine ?? and it's very low mileage.
IMHO....your oil pressure didn't justify the teardown...25PSI at hot idle?? lol...45 on the highway??? = Acceptable
GM spec is 10 PSI per 1,000 RPMs
If I were you and trying to get it done the "half azz" way, I would at a minimum, clean it all up, have the crank polished, check and re-size the rods, new bearings, and check clearances. Depending on which way you go, you may be tearing it down again in 500 miles.
IMHO....your oil pressure didn't justify the teardown...25PSI at hot idle?? lol...45 on the highway??? = Acceptable
GM spec is 10 PSI per 1,000 RPMs
If I were you and trying to get it done the "half azz" way, I would at a minimum, clean it all up, have the crank polished, check and re-size the rods, new bearings, and check clearances. Depending on which way you go, you may be tearing it down again in 500 miles.
Last edited by badazz81z28; 05-11-2013 at 03:26 PM.
05-11-2013, 03:31 PM
#5
There's a right way, a wrong way, and a half azz way to building engines...The choice is yours... Honestly...don't throw out there that ARP rod bolts will live in an engine without re-sizing, resizing is the "right" way to do it. It may be ok in your engine, but not ok in another. Beside, your having issues with your engine ?? and it's very low mileage.
If I were you and trying to get it done the "half azz" way, I would at a minimum, clean it all up, have the crank polished, check and re-size the rods, new bearings, and check clearances. Depending on which way you go, you may be tearing it down again in 500 miles.
If I were you and trying to get it done the "half azz" way, I would at a minimum, clean it all up, have the crank polished, check and re-size the rods, new bearings, and check clearances. Depending on which way you go, you may be tearing it down again in 500 miles.
If you can't tell, I have no one knowledgeable locally to ask. The only machine shop in town says he has never built an LS1, so I can't ask him about any of it or have any of the work done by him. So any way you go, I'm going to be entrusting my engine with someone I don't know and won't be close enough for me to drop in and check up on or ask questions. So, forgive me if I'm trying to understand the WHY before I just go throwing parts and money at the damn thing.
Everyone preaches about how reliable and awesome these motors are, and yet two of the three I have owned have had major oiling issues for no apparent reason. I run synthetic oil in them, changed every 5000 miles (overkill), I don't race them, they are not highly modified, and I never rev above 6200. Yet for some reason I am getting lectured about "not doing things the right way".
Now, can we try to start this again?
05-11-2013, 03:35 PM
#6
Also, for your edited comment of "your oil pressure did not necessitate teardown", I think you would disagree if you KNEW FOR A FACT that this motor used to make 20psi higher across the board than it does now. You would KNOW something was wrong and you would not TRUST IT to drive far from home in without knowing if a rod or bearing was about to fall out the bottom of it.
I would consider that "doing it right".
I would consider that "doing it right".
05-11-2013, 03:37 PM
#7
My intention was not a lecture...
For an engine to last and be reliable, it has to be built right. All these issues tend to end up at Human Error most of the time. Installing ARP hardware and not re-sizing the rods is just the wrong way to do it. It makes you wonder "what else" was done wrong.
Was the engine oil primed before the first start-up?
My advice would be to either tear it completely down and rebuild it or sell it and buy a complete 6.0 or something.
For an engine to last and be reliable, it has to be built right. All these issues tend to end up at Human Error most of the time. Installing ARP hardware and not re-sizing the rods is just the wrong way to do it. It makes you wonder "what else" was done wrong.
Was the engine oil primed before the first start-up?
My advice would be to either tear it completely down and rebuild it or sell it and buy a complete 6.0 or something.
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05-11-2013, 03:49 PM
#8
Installing ARP hardware and not re-sizing the rods is just the wrong way to do it. It makes you wonder "what else" was done wrong.
And since there is no such wear present on my rod bearings, wouldn't it be reasonable to say that they did not cause any issues with rod bore warpage in my specific engine?
So putting that aside, what else do you have to do to keep an LS engine alive? Keep it full of coolant? Check. Not let it overheat? Never been over 215. Check. Keep it full of quality oil that is changed regularly? Always had castrol synthetic changed ever7 5k. Check. Not rev it too high? Rev limiter set to 6200 in my truck when it last ran. Check.
Tell me...what more should I have done differently? Is there a magic wand I was supposed to have waved over this thing to "do it right"? I'm being serious here. I want to learn what I have done wrong, so that it does not cause any future problems.
Was the engine oil primed before the first start-up?
When I swapped it into the corvette I repeated the same priming procedure since it had sat for a year+ since it last ran. It had 6 quarts of castrol synth 5-30 in it when it lost oil pressure.
My advice would be to either tear it completely down and rebuild it or sell it and buy a complete 6.0 or something.
Last edited by RotaryResurrection; 05-11-2013 at 03:57 PM.
05-11-2013, 05:31 PM
#9
Your cam bearings look rough to me. Any nicks at all in them is not good and will cause pressure drop. The ARP rod bolts made the rod bearing wear in odd and got loosened up due to the rods not being honed after ARP install. These 2 things combined to make it lose pressure, and the more pressure you lose the faster you lose it.
05-11-2013, 06:23 PM
#10
TECH Addict
I would take the heads off and do it right.I don,t see why you would have to mill the heads again. Just get new head gaskets and clean them.You might be better off just getting a short block and put you heads on that. I bet the price wiil be pretty close and you will know everything will be new and right.
05-11-2013, 07:22 PM
#13
I would take the heads off and do it right.I don,t see why you would have to mill the heads again. Just get new head gaskets and clean them.You might be better off just getting a short block and put you heads on that. I bet the price wiil be pretty close and you will know everything will be new and right.
New? Used? Why would I be inclined to trust a used motor, when no one can explain the problem with this low mile rebuilt motor?
05-11-2013, 09:05 PM
#14
Why would they need to be milled again? There is nothing wrong with removing the heads and then reinstalling them as is. Only need to mill them to get them flat in the event you've over heated the engine or want to raise compression.
05-11-2013, 09:12 PM
#15
It looks like the bearings have groves in them. Can you feel those lines with your fingernail? Do you run a magnetic oil drain plug, or have u cut open your oil filter to check for metal shavings or foreign objects?
05-11-2013, 09:12 PM
#16
I was under the impression (from like, every mechanic and machine shop I've ever been around) that you had to machine the head anytime it came off, and that failure to do so was not "the right way".
The problem I have is there are so many opinions with this stuff. One guy will say X is fine, another guy will say it is junk, another guy will say it's completely okay to reuse, another guy will say you can't. It's hard to know who to believe.
Last edited by RotaryResurrection; 05-11-2013 at 09:18 PM.
05-11-2013, 09:17 PM
#17
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25 psi @ hot idle and 35-40 revving on a manual gauge is no cause for alarm. Was the 45-70 psi in the truck recorded with a manual gauge or with the trucks not so accurate gauge? Personally I would have let it ride, but I suppose that ship has set sail....
At a minimum, I would re-bearing and polish the crank and resize the rods. Don't really care for the looks of the cam bearings either. Anything short of that is a crapshoot at best.
At a minimum, I would re-bearing and polish the crank and resize the rods. Don't really care for the looks of the cam bearings either. Anything short of that is a crapshoot at best.
05-11-2013, 09:23 PM
#18
25 psi @ hot idle and 35-40 revving on a manual gauge is no cause for alarm. Was the 45-70 psi in the truck recorded with a manual gauge or with the trucks not so accurate gauge? Personally I would have let it ride, but I suppose that ship has set sail....
At a minimum, I would re-bearing and polish the crank and resize the rods. Don't really care for the looks of the cam bearings either. Anything short of that is a crapshoot at best.
At a minimum, I would re-bearing and polish the crank and resize the rods. Don't really care for the looks of the cam bearings either. Anything short of that is a crapshoot at best.
Then the same dash gauge was indicating 16-20psi oil pressure at idle after (whatever happened) happened.
Then a separate mechanical gauge was also applied and it agreed with the electrical dash gauge...it showed maybe 5psi more than the dash gauge, but that still put the engine at 25 @ hot idle and 35-40 driving.
Now if that motor had showed similar numbers from day 1 of it's life, then maybe that would be one thing. But for it to have 65 one minute and 35 the next, something has happened suddenly somewhere along the line and it would seem irresponsible not to find out how it got hurt and fix it.
I'm sure if I had run the thing until it lost almost all pressure and then took it apart to find out it was a boat anchor, some of you guys here would have been the first ones in line to lecture me about being dumb by running it after I knew it was hurt.
