Piston Slap??

[Kyle C.]

I have an '02 Yukon 5.3 just turned over 100k that makes a loud ticking/knocking noise when I start it up in colder weather (50 and below), it almost sounds like a deisel when i rev it up a little. Goes away a few seconds after I start driving. Is this a bad thing? I hear its fairly common but it just doesnt sound right...

More importantly, I notice "kind of" the same sound when accelerating right before the tranny shifts (alomst a rattle, or ticking), only when I'm getting on it (high RPMs) to pass and its only sometimes. It doesnt sound like its the tranny, its comming from the engine compartment. Is this an issue or causing loss of power? Could this cause a larger problem or is there a fix?

Thanks guys

 

[Redhoe01]

I hope its not bad, I have the same thing when I start mine in the cold. It goes away after a few minutes so i dont drive it till that noise is gone. Mine is at 138,???

 

[sschrader]

Mine does the same thing, mine has 165k on it.

 

[rich5368]

Piston slap is common in these trucks. Both of mine do it. My 04 has 156k and my 03 has 116k. Both run like new. Wouldn't worry about it. Just don't get on it hard until it stops doing it. Mine usually goes away within a minute or two of starting the truck.

 

[BOSS]

Some of the hardcore Seafoam fans are going to flame me but mine started slapping a hair in the winter just shortly after running it in my oil a few thousand miles...could be coincidence, SF is supposed to lube the rings etc...I hit 120k the other day so who knows

B

 

[Kyle C.]

I've thought about that Seafoam.. Any idea if that would help the sound I hear at the higher RPMs?

 

[slocaddy]

my 03 caddy w/5.3 and my wife's 99 z71 w/5.3 also do the same thing. my truck has 146.*** and hers 170.***. Mine hardly ever does it , but her truck does worse on cold mornings. I took it by the shop for my mechanic friend to check out and I'm pretty sure it was on all-data that the noise w/cold start up then goes away w/ warm up is a common problem on these trucks and actually had something to do with the oil pump sucking an o-ring from where the pick-up tube attaches. not saying this is your problem or the correct answer but something I've found out myself.

 

[Jamison]

My '02 did this also at cold starts for a few mins and then it goes away. I've switched to 89 octane gas over the past two weeks and the startup noise is gone and the ticking that it made when punching the gas is definitely gone...

 

[blueflamed03]

common complaint

 

[rich5368]

My '02 did this also at cold starts for a few mins and then it goes away. I've switched to 89 octane gas over the past two weeks and the startup noise is gone and the ticking that it made when punching the gas is definitely gone...

I've never heard of higher octane fuel fixing piston slap. Too bad no gas station here sells higher than 91 otherwise I might try it. Maybe what you had was pinging not piston slap.