Lifter noise on 2002 Coupe

[bowtiebandit]

Admiral..I own an 03 and it has all sorts of quirky noises..I dont worry about them much. Since I make a living fixing them I can honestly tell you that I have never seen any of them blow up.

I have done more re-rings than I can count and quite a few replacement of the polymer pistons for noises. There is also a TSB out for a possible split o'ring on the oil ump pickup for ticking in the initial start and then returning when warm.

I hope your situation is resolved to your satisfaction.

Thought you might like this..these are pics of one of the last ones I did.

http://f1.pg.photos.yahoo.com/ph/zingr67/lst?.dir=/LS1&.view=t

 

[theplayer]

Update: The dealer had my engine out to check for damage/tolerance problems because of the engine knock. I got my hands on the pistons that came out of it. Some of them had the black coating on the skirt worn off or slightly worn off. I could see a few small black lines in some of the cylinders due to the coating wearing off. I asked if that was bad and they said no it won’t hurt anything. I asked about the coating wearing off and they said that’s normal because that is what the coating is for. He said since the skirts were so short they had to coat the sides because they know they will touch occasionally. A mechanist came to measure the cylinder bore for taper and out of round. Everything was in spec according to him. He didn’t know why it was knocking. Dealer said that they were still going to put new pistons in it though. I just don’t see how that will help if the tolerances are in spec. What caused it to knock in the first place? The mechanic actually told me that after he put it back together that it might be quiet for a while but would probably start knocking again because “they just do that”. I don’t know what to think anymore. At least they are doing something I guess.

 

[Zen]

lifter noise

I was advised that the noise is from the AIR pump and valve. You can check this out by removing the 20amp max fuse for the pump to see if the noise disappears.

 

[jsinga]

Man, I think you guys are overdoing it. If the thing shuts up after it warms up you just have what we used to call cold piston slap. Go listen to a couple of 60's hot rods. The pistons are aluminum, they grow when they warm up. Piston design has some effect on it to. It's not a buick!
Now if it uses oil, anymore that very little then take it in.

js

 

[theplayer]

Well let me wrap up my story on my piston knock saga. After getting the motor out they measured the bore and the pistons to see if the tolerances were correct. According to the mechanist that measured everything was in spec and he could see why it knocked. The cylinder walls were not scored although there was some polymer from the piston skirt on the walls and some vertical lines that looked like fine scratches. The walls felt smooth to the touch though. GM told them to put new pistons in it. I didn’t see how that would solve the problem since everything was in spec in the first place. So they put new pistons on the existing rods. They also used my original rings because they insisted that it would use oil if they put new rings in it. They said if the cylinder was re-honed then new rings would be ok but once the rings have set they are told to put the old rings back in. I have seen that in one of the service bulletins anyway. So they put everything back together and did a pretty good job. Everything under the hood looks like it use too. I found one connector that was unplugged but I found the other end and plugged it up. I have no clue what it was because I wasn’t getting any error messages. Anyway the results! After all this it still has a quiet knock at startup. It sounds like it use to but the knock is much quieter and I don’t think it lasts as long. So it’s better that it use to be at least. I don’t know why some engines knock and some don’t. I am just going to live with it and see if it gets worse. Overall they did try to fix it so that was good.

 

[vettenuts]

New information may be forthcoming. Check out my new thread on Piston Slap. I think Terry may be on to something, and plan to keep and eye out for his findings as well as submitting my next oil analysis to him.

 

[RUDYBKK]

Yeah i got it on 2004 LS1 RIGHT REAL at start up was told it is an
"expansion problem " and will do no harm Going to dealer next Monday
to hear the evaluation

 

[schmaltzr]

What O ring specifically

I'm ASE certified master technician and work at Gordon Chevrolet in Jacksonville FL. Let me start with the lifter noise after cold start. It is normal. There is nothing to be concerned about. Now, for excessive oil consumption there is a bulletin that addresses an o-ring that was probably cut when installed when built. There is also an updated engine calibration to address engine knock and fuel gauge going to empty while driving.

What O ring specifically. I just went through a bit of oil (2 quarts in 1200 miles). I've been driving it a little more aggressively, but not racing it. No great oil drips underneith, (dealer found a single drip on starter bolt), garage floor has a single drip once in a great while, and no real smoke as far as I can tell. Dealer thought it would be maybe the rear main seal, but I wasn't going to spend $1,000 to find out. I'll live with it until it gets worse or there is a cheap fix.