SporkLover

iTrader: (2)

Well I'm currently trying to diagnose an engine sound and just need some opinions from you experts.

The sound is a ticking/tapping....

Symptoms

1. 30 seconds after starting, the engine will start making the noise. It will be quite noticeable. After the engine is fully warmed up it will go away, or be very quiet, meaning you practically have to have your ear on the intake to hear it, and the noisy injectors almost drown it out. I start the car in the garage, so things are a little louder in there. If started outside of the garage, the noise is very hard to hear. Until the engine is warm, the sound increases with RPM.

2. The sound is also there after shutting off the engine and starting it warm, like if I had to run into a store for a moment or two. The sound wont last as long, for a minute or so.

3. Sounds like its coming from the top of the engine, but it can also be heard clearly from underneath the car. It's loudest from the top. If you try to listen through the wheel wells, its not as loud. When listening from the top its louder from the drivers side.

4. It's hard to diagnose the speed of the sound as fast or slow, because those are relative terms. I would say that the sound is slow.

Running Conditions of the car:

1. Oil pressure is great, from cold start the pressure gauge shows 40 - 50 psi. When idling the oil pressure is at 40 psi, after the engine is warm. It hovers at 40 psi until I drive it agressively, then it hits 65-70psi.

2. Engine runs smoothly, I need to scan it to see if there is any misfires, but I don't feel any misfiring, and it revs cleanly all the way to redline. Doesn't run rough or anything.

3. codes, no codes whatsoever.

Based on what I have read I believe it to be a lifter. I thought it might be piston slap, but seeing how it takes so long for it to go away(when the oil warms up), I thought that it might be the valvetrain. Tomorrow I'll pull the valve covers and inspect the pushrods, and retorque the rocker arms, but I just wanted to tap into the wealth of knowledge here.

thanks for your thoughts

SporkLover

iTrader: (2)

I know someone here has to have some input

SICKBIRD

could be the lifters

tirefryer

It's piston slap. Mine does it exactly as you described. If it's not burning oil doen't worry about it. I think loose=fast!

mcd_57

my car does the same thing. more input guys

CrawlinWS6

iTrader: (41)

Hell, I don't think I have ever heard an Ls1 that has not had that sound.

mcd_57

My '99 C5 has never made this sound, only SS.

CrawlinWS6

iTrader: (41)

there is exception with everything, but it is very very common sound on ls1's

andy1h2004

So is it hard to change lifters or can they be fixed, how many are there and, where can they be purchased. . .

johnpate01

iTrader: (3)

What about the AIR pump and associated check valves. Mine had a problem similar to that and (new to me) used pump and check valves fixed it. Or it could be the lifters, can you post a sound clip?

~JOSHUA

iTrader: (92)

I have an idea. Mine did a similar thing 'till I changed motor oil brands. *piston slap* Mine would be quiet at cold start for about 40 seconds then have a marble(s) in a can sound until I put some heat into the piston. Even if the temp was up it needed 30seconds of driving and it would go away. The same thing would happen on a warm restart. It's from the barrel shape the piston is cast in rocking in the cylinder bore. I went from Mobil 1 to Royal Purple oil and the "slap" is barely noticable now. Try changing the brand of oil. Hope this sheds a bit of light.