y5mgisi

iTrader: (2)

Goes pretty much silent when warm but is very noisy cold.

crainholio

iTrader: (2)

Piston slap usually happens when opening the throttle, yours seems to happen when you release it...lifter noise most likely.

Fast98Z28

Sounds like a lifter

RockinWs6

Its lifter noise, when the engine is shut off the lifters and oil gallery drain down so when you start cold the lifter get a shot of air and they clatter until the oil warms up. Its possible you have a leaky oring at the oil pump, this can let the lower oil gallery bleed down and cause a lot of noise at every cold start.

Piston noise or piston slap sounds EXACTLY like a diesel engine running. Most dealers will say lifter noise is piston slap, I'm not sure why???? I think because piston slap is acceptable according to GM but lifter noise is not SO if its diagnoses as piston slap its ok?????

If your engine made that much noise from loose fitting pistons it wouldn't be running very well and be smoking oil out the exhaust so don't let anyone BS you.

Fast98Z28

I hate piston slap...

Sales2@Texas-speed

iTrader: (5)

Sounds a lot like lifter noise to me.

y5mgisi

iTrader: (2)

Thanks guys! For the record, this is a lq4 motor out of an 02 Denali that a friend just finished swapping into his 91 suburban.

y5mgisi

iTrader: (2)

Oh, another thing of mention is that we went around and unplugged each of the coils while it was running and did tye same little rev for each of them. The noise persisted with each coil disconnected. Our thoughts were that if it was slap, when we un plugged the offending cylinder, the noise would stop. But it never did.

2000PewterT/A

Like everyone else said, it sounds like a bad lifter.

y5mgisi

iTrader: (2)

Sounds good. Any ideas on the best way to determine which one it is?

crainholio

iTrader: (2)

Mechanic's stethoscope, probe the valve covers above each cylinder to find which one is the source.

Crimsonnaire

iTrader: (1)

I have a tick that sounds the same as that which I've been trying to figure out if it's piston slap or lifter. I'm gonna try to shoot a video of it, but the characteristics I've been able to determine so far is that it first appeared after a mechanic revved the engine aggressively in neutral (close to 5k RPM) many times, and that it's most notable in cold winter starts with it still being fully audible at hot OT but at low RPM.

Does anyone have a video link of an actual piston slap for comparison sake?

RockinWs6

I'd trying changing oil and filter 1st and honestly I've heard the noise you have in so many of these engines I wouldn't bother doing anything unless it gets a lot worse. Its not hurting anything.

Russ K

iTrader: (1)

Sounds like a collapsed piston.

Russ Kemp