EDDIEX

I just got my car outta the shop today. I had taken it in for an engine noise, the noise being a tapping sound while the engine is cold.

It is a stock '02 Z28 with 16000 miles.

The engine makes the tapping sound when it is first started in the morning and continues until the engine has reached operating temp. (approx. 15 min.)

It also taps upon restarting, if it has sat long enough to cool down.

I was told that it is not abnormally loud and carries good oil pressure and that the noise is coming from hydraulic lifters which are not abnormally loud, so no repairs were made.

I am mainly trying to find out if anyone else is experiencing this and if I should pursue trying to have it fixed. The car is still under GM Protection Plan.

Have a Great Day.

kenp

iTrader: (9)

W/O hearing it it is hard to say. Some valve train noise is normal with the LS1. Some piston slap on cold start is normal. If you have a mechanic's stethiscope you can try to isolate the noise. Unless you've used the stethiscope to listen at the valve covers, I wouldn't be so sure it's valvetrain noise. There are countless things that can make that ticking sound. If you have an M6 and you've missed a gear and bent a pushrod it can make such a noise. Could also be an exhaust tick. Have you had the car for a while and just noticed the noise?

orangeapeel

iTrader: (18)

could be a spun bearing, bt it doesnt sound like that would be the case.

777

iTrader: (21)

Piston slap would be my guess. It's completly normal and most ls1's have it.

slow trap

iTrader: (22)

i'd say piston slap also since it stops when warmed up. i wouldn't worry about it.

EDDIEX

I bought the car new. I did notice the tapping in the past but it seems to have gotten worse over time. I don't know if it's because other people are bringing it to my attention but it doesn't sound normal to me either.

It has an A4 transmission. I like driving it but I don't drive it like I stole it.


Excerpt from Service order: (Chevrolet Dealer/Service Dept)

Checking serveral times with tech, shop foreman and also by service advisor, noise is not abnormally loud and vehicle carries good oil pressure, noise is coming from hydraulic lifters not abnormally loud, no repairs made.

End excerpt.


I had thought it might be piston slap, from what I have read and understand though, piston slap doesn't last that long. Is that right?

I will be doing some more listening of my own but from what I've heard so far, it does come from the valvetrain.

Thanks for the suggestions.

Predator

My car had similar noises, but after installing a cam with new pushrods, valve springs, Ti retainers, and retorquing the header bolts, all is well. I always believed it was either tightening the header bolts or replacing the pushrods that solved my problem, but I don't really know for sure.