I have a '01 C5, A4 equipped and have been hearing a noise that sounds like valvetrain, usually loudest on restart after driving and letting her sit for about an hour or two.oil pressure is 28PSI +/-5 PSI @idle, and I do hear it when stopped at lights occasionally. I am an ASE master auto tech with L1, and after hearing the noise I sumply cannot accept Chevy's answer that the sound is normal. Has anyone had this problem, and is it aa acceptable flaw or is there a fix? Thanks for any info you may have.....

 

NJVetteGuy:

Sounds like the noise we have discussed before which sounds like a slight tapping sound when the engine is warm, then goes away after about 90 seconds. Although it doesn't sound pleasant, the general consensus was it was not due to a problem, but rather a cold piston slap. I can live with it rather than have them tear the engine down to due something that is really not necessary.

 

I would accept it, except for the fact that it still occurs after warmup, I have heard it after getting off the highway and stopping at the end of an off-ramp. I have yet to put my stethoscope to her and verify it is valvetrain noise, but it definitely sounds like an upper end problem from what I have heard so far. Thanks for the reply, I think I have heard the noise you're talking about on my friend's '00 convertible but his only happens when cold, mine happens cold or hot....Thanks for the quick reply and I will post any more info I might gather up.

 

I think I've got the same noise but I might be a little gun shy about the lifters. I'm in the middle of negotiating with dealer/GM to fix/ replace my engine due to no oil pressure on start up.

This issue caused a set of lifters to get toasted while idling in my garage this summer. Something cause Mobil 1 to burn (coke) inside the engine, which eventually caused the oil pickup tube to majorly clog.

When my oil pressure got real low I definately heard lifter noise again and had the car towed to the dealer. The dealer pulled the oil pans and cleaned up the burnt oil and gave it back.

The dealer gave the car back 2 quarts low on oil and did such a good job cleaning the oil pans that now I get a low oil warning at start up, on the road, and everytime I shut it off.

The engine seems to vibrate a little more than it did before (could just be me) and I think I hear valve train noise under light acceleration around 2-3,000 rpms.

Every time I hear a rattle coming from the engine I fear lifters.

Yes, it's going back to the dealer tomorrow, I wonder what kind of rental I'll end up driving this week. (I actually got a Ford Festiva once with 40k miles on it)


[Modified by Gary2KC5, 6:43 PM 10/2/2001]

 

I think I have heard the rattling noise@ 2-3000 RPMs also, after you get the car back I'd be very interested to hear the results. I wonder if anyone knows of LS1 oiling system upgrades that are available that won't void the warranty, or if anyone has tech info on this engine so I can find a way to bump the pressure up like we used to do on the first gen small-block chevys with a different relief spring in the oil pump and chamfering the oil holes in the crank, etc. I'd appreciate any info that anyone could give me......Thanks in advance for any replies.

 

The Dealer and the GM rep finally decided to disassemble my engine and they found the stuck open oil pressure relief valve that I told them they would but here is some interesting conversation the GM rep had about piston slap and what the service manager told me about the coked oil that might be important to your situation.

While discussing the 3 trips i've had to fix a low oil pressure problem without looking at the oil pump I brought up the oil consumption issue and that the dealer had documented it since the last oil change. I began to tell him of the common knowledge of the defective piston rings on the LS1 engine.

The GM reps begins to explain why engines can be manufactured with tolerences on the far end of each other (cylinder wall on the high side piston on the low) I interupt him to tell him that is what's called piston slap and my car doesn't do that. He then suggests we replace the piston and while the egnine is disassemble we look at everything else.

They torn it down and told me the pistons had too much clearance and that was causing the oil to coke. I have another theory about the coked oil but if what they say is right and I didn't have piston slap noise, what's happening with blow by on engines that do have the noise.

I would change your oil often and check for burnt chunks and particles, maybe get an oil analysis done also. If you find any get to the dealer for new pistons.

BTW: when dealers and GM tell us that things like 6 psi of oil pressure and lifter rattle, and piston slap is normal they are probably correct because it has become the norm for them. It may be normal to them but it is still not right.


[Modified by Gary2KC5, 8:50 AM 10/5/2001]