Hey guys, I just got my LS2 back together today after replacing a broken piston (detonation) and bent pushrods (over rev). Got it all done and fired up and the valvetrain is noisy as hell and I'm barely getting any oil up top. I do not have a gauge on the car to check pressure, but there is obviously an issue. I pulled the pan again to check the o ring on the pick up and basic stuff, I even pulled the rod caps to make sure the bearings weren't running dry. O ring, pickup, oil pan gasket, etc. were all good and bearings looked fine with what appeared to be plenty of oil going to them (but the car has not been driven, just idled- not going to risk blowing it up obviously).

I know these cars have oil pump issues, but I can't see it being good prior to parking it last week and being bad now. Is it possible something in the pump broke when it was over revved (~8400 on a mis shift) and just reared it's head today when I fired it up? Also, when I was doing the ARP's and rotating the crank with a socket, I would hear a "click" that sounded like it was coming from the oil pump area with every rotation, but I just assumed it was because there was no oil in the pump and the pickup and such were off, maybe not....

Is it possible to pull the pump without dropping the pan on this motor? Is it possible there is a broken bypass spring or something? Or- should I be looking elsewhere? I would hook a gauge up to check pressure, but it is obvious it has to come apart anyway.

Last thought- I bought Trick Flow pushrods from Summit (stock cam, springs, etc. so I didn't need anything crazy)- any known issue with them? Although, they should be fine- the length was the same, etc.

I just figured I'd ask those who have had the engine apart and/or had oil pump issues before going much further. Thanks.
Joe

 

Is it possible you have an air bubble in the system? How about priming it first? I have not worked on the LS2 but isn't the oil pump mounted on the front of the engine? You should be able to remove it from the front. I'm just going from my past experience working on Chevrolet Small and big blocks. Good luck and let us know what you find.

 

I was wondering that, but there really is no way to prime it that I am aware of since the pump is driven off the crank. It should have pumped up by now- there is about 5-7 minutes run time on it and it has not improved any .
Joe

 

Any other ideas?
Joe

 

I thought you would get more help on this. What is your oil pressure?

 

Before we get into this, did you just change one piston? In other words I am trying to ruls out any other damage from the first go round that might not have been obvious

 

In the old days, no way I would leave an old oil pump on a motor that was being put back together from any sort of breakage...

 

You broke a piston from an 8400 rev, I don't think that is detonation.
Here nor there, the LS oil pump are very sensative to debris. The relief valve has tendencies of sticking open causing the pump to be in the bypass mode at all times.
You must at least clean and inspect the pump asm after debris passes through the engine. But you should have replaced the pump during the other maintenance.
You must drop the sump to remove the pump or access the relief bore.
That shouldn't be that big of a deal since you have already dropped the sump for other inspections.

 

Thanks for the replies guys- just to clarify- the piston may have broken from an over rev, but it appeared more to be detonation- the "corner" of the piston head above the top ring and the ring land right below it were broken. As for never replacing an oil pump when damage occours- it was the piston head and that only, no chunks, shavings, particles, etc. in the pan- it was a clean break and out the exhaust valve causing no other damage. Hell, the only reason I even knew it broke is because the piece that broke off hit the plug, closing the gap and causing a misfire. The car ran strong with no issues and several *** whoopings for over 300 miles since the over rev with no noticeable problems until I had it on the dyno and it started to misfire- no immediate destruction when it happened.

This is not my first engine repair, rebuild, etc- I know what to look for when there is damage to a motor- all the other pistons and ringlands were fine, valves were not crashed, etc. and, as I said- it ran great and even put 648 to the wheels with the broken piston and misfire (I didn't lift immediately since it showed very rich on the WB and I thought it was just too rich of an alky shot at the time). Nothing else aside from the pushrods looked to be damaged from the rev.

That is all why I am stumped as to what could be wrong and asking others who may have bad oil pump on an LSx motor experience. Only particles of anything that I found in the pand after removing it a second time were some small flakes of the sealer from the headgasket (silicone?)- I can't see that causing a problem, but again- wanted to ask those with more LSx oil pump experience than I. Thanks.
Joe

 

It has to be primed like any other oil pump. There is a pre lube port on the drivers side of the engine or front cover I don't remember exactly where. You have to pump oil into that hole to prime the pump.

In addition, you still have to soak the lifters in oil prior to installation.
Just like the older engines everything has to be primed and have oil pressure before starting otherwise you will be replacing more than a piston. Once the engine has been primed rotate it without the plugs and you should see oil up top. Good luck

 

Thanks for the reply. The thing is- the motor was never removed from the car, flipped over on a stand, etc.- it was just a pull the heads, pan and replace the broken parts. Unless sitting with no pan, oil, sump, etc allowed the pump to completely lose everything and it will not prime itself (even though the craqnk and bearings did have oil when I pulled it apart). Lifters were not replaced, the ones where the bent pushrods were had been removed and visually inspected to make sure the plungers weren't broken or anything- I can see those 3 being noisy, but not all 16. This is all why I am so stumped, there are many things it could be, but none of them really make much sense- unless it is a prime issue from the car sitting disassembled with no oil. I'll look for that oil pre lube port. How do you add oil there- is there a special pump, or can you just put some in that hole? Thanks.
Joe

 

"there is none so blind as he who will not see...."

Okay, I was gingerly polite, but now I am going to be direct, but all in an attempt to help you:

You are a conflicted person. Just like Steve Irwin, you claim you know what you are doing, and yet something unexpected has happened that you failed to understand. With him, he had previous nips, bites, scratches, near misses, public concern, offical inquiry, media backlash, friendly warnings, unfriendly warnings, was drug by his pants, fell down, was dragged into water, slipped, and yet somehow he could claim with a straight face that he had it all under control even in light of all those many precursors and portents. Of course he is a dead man now....

Likewise, you are puzzled enough to reach out for input, but you think you will know what you ought to hear when you hear it, but you didn't know it enough to avoid needing to ask.

So I say again: I don't care if you think it spit most of the piston out of the exhaust; when you have parts coming loose in a recipricating assembly, when you subsequently disassemble it for repairs, ALWAYS use a BRAND new oil pump.

There, how's that?

 

No offense taken at all, I just never really heard anyone say that before. I have worked in general repair shops for over 15 years- just always "replace what broke". I have replaced numerous pistons from nitrous issues to too much boost on several forced induction cars and have never had to touch the pump- some had over 100k and still had good pressure with no pump damage. I personally have not seen one bad oil pump in all my experience- maybe I am just lucky, who knows. So from my personal experience and the fact that this motor has 7500 miles, I never really thought it would "need" it. As for replacing it every time the reciprocating assembly has a part replace- good rule of thumb, probably- necessary, I don't know. I have seen several tear downs for broken pistons where the pump is never even removed from the motor by shops who have much more experience in the than I do.

Now if head gasket material from removing the head is enough to stick the valve and that caused a problem, then that would have happened regardless of touching the reciprocating assemble. If it was from the over rev- then, that is not from replacing anything in the reciprocating assembly either and I probably should have replaced it- but the few people I spoke with said the RPM's would not hurt the pump and again, it was fine before I parked it.

Trust me, I am not just waiting for someone to say what I want to hear, I am listening to everything said and just comparing to what I know about what happened, how it worked prior and my experience. I am going to put a gauge on it today to see what the pressure is (the damn GTO does not have one!!!) and I'll know more from there. If there is no pressure, the pump is coming off. If there is, I am going to have to look to the top end- but I doubt it is there. I am leaning towards the pump too, I just don't know why it worked before and not now- that is what does not make sense to me. Thanks again.
Joe

 

Bah, I think I'm just going to pull it to be safe. I really don't want to start it again to check pressure since I am not 100% sure what is going on and I don't need to kill the bottom end- even though luckily, the bearings looked to be getting oil. I'll let you know what happens. Thanks.
Joe

 

There Is An O-ring That Seals The Pickup Tube To The Pump Itself, It May Be Missing Or Not Sealing Causing Low Oil Pressure. This is really common and probably the case if this was removed. There Is Also A Plug In The Inside The Rear Cover That Slides Into The Block That Directs Oil Flow, If That Is Missing Or Installed Backwards, No Oil Pressure.

Good Luck!

 

Thanks Nitro- I actually pulled the pan and pickup after I noticed the low pressure to make sure the O ring was seating properly. It seemed fine, no dents, gouges, etc. to indicate it was pinched. When I reassembled it, it seemed as if the pickup was stopping about 1/16" or so away from the pump housing, I assumed that was the o ring making contact with its sealing surface and then I snugged it the rest of the way with the bolt. I have read other people saying not to draw it in with the bolt, but I don't know if they meant what I did and the o ring and tube were supposed to pop in or something until flush, then put the bolt in- or if they meant not to just pull the whole ting up into the pump with the bolt.

I have done work with several motors with an o ring on the pickup and you just basically hold it in place and tighten. Is this one supposed to lock in somehow first? Thanks again.
Joe

 

Sounds like you did it correctly. Were any plugs removed from the block, #1 you need to put a oil pressure gauge on the car, I think software will read the oil pressure on vettes, Do you have hptuner? If not, pull off the little block right above the oil filter with the 2, 10mm bolts and drill insert an oil pressure gauge line into it. See what happens.

 

Well said.

 

If you want to fix it right after a broken piston: Remove engine, field strip it to a bare block. Send block and heads and rotating assembly to a machine shop for remanning, blueprinting, and balancing. Have them check out the bore and select what pistons it will take after the bore clean up. Same thing with bearings. It all has to be checked, to do it right.

Then prelube it prior to start. Any engine can be prelubed. Hook up a preluber to the oil pressure port or galley plug. Then crank the engine with fuel and spark disabled to verify the oil pump is building pressure. Then you think about enabling the fuel and spark for it's first actual start. If the engine was not removed from the car, I can't see how it could possibly be fixed right. There are so many possibilities for debris to be left behind.

 

Once again guys, I know "right" from wrong- there was absolutely no debris in the pan, no aluminum shavings, no chunks, metallic residue- nothing, the bottom end was clean and new. All the bearings look brand new, the filter had nothing in it (cut it open earlier just to be sure since you guys are pushing the debris issue). If it broke a piston and did more damage than what it was, I would have pulled it, torn the whole thing down and gone forged. There is no way there was any further damage than the broken piston- this is not my first time repairing a broken motor. I came here, not to act like I know more than I do- but to ask what would prevent the lifters from pumping up aside from the basics in case there is any LSx specific quirk I am not familiar with. There are many people who rebuild these motors and just put assembly lube in the pump and make sure the bearings are coated fine and they have no issues just starting it up and let it build pressure, so I can't see how a motor that was already "wet" inside can't pump the lifters- and I am wondering if there is anything else to look for.

Also- I just took the pump out and apart, and as I suspected- it is like new inside, no damage, galling, DEBRIS, etc. The bypass was clean and moving freely, etc.. The pick up o-ring was damage free and properly seated also, so I am stumped here. I can't see all 16 lifters going bad, so it has to be something else. Either it just is air locked up top for some odd reason (although it has been running long enough, it should have passed) or something else. Anyone ever use the Trick Flow pushrods? Those are the only other things changed, but they are a simple part, can't see them being the problem. They are the correct length also BTW.

I came here asking those who may have encountered a similar issue what it may be and all I get is "you did it wrong"- I'm sorry if I don't completely tear down and rebuild every motor that ever has a problem. I tear it down, assess the damage and go from there. There are several motors that I have had to go through the whole thing after a break, but this motor did not and does not need it. I just need to figure out this issue, that's all. The culinder was clean, no scuffs, grooves, lines, etc., heads also held vacuum just fine. The damage and repair to the piston is absolutely not the issue here. I already pulled the pump since so many of you were convinced I did it wrong and the pump was bad for no reason- only to find it in perfect working order. I'll get it figured out. Thanks to those who have helped.
Joe