Piston slap in 5.3 Tahoe

[stbeverlin]

I'm trying to find a thread relating to the piston slap problem inherent with the 99-2002 5.3 engine. My 2000 Tahoe started making the noise at about 70K and does it only on cold startup for about 30 seconds, then goes away. I've tried several good filter brands including Wix, Pure One, and Mobil 1, all with a good anti-drainback check-valve, but it didn't make any difference. I use Mobil 1 synthetic and have tried 5-30 and 10-30 viscosity, with no change.
GM says it won't hurt anything, but common sense says if there is a knock, its not good.
Any ideas or comments??

 

[EliteTahoe]

I think maybe I saw this thread a while ago...
The thread had info about this start noise on chevy engines, but it also said that you were'nt able to do anything about it.
No oil and no parts where able to get rid of this piston slap.
I believe GM had a reason to say this to you.

Ontopic: Don't remember where this thread is.

 

[Sepiroth]

Yea piston slap is something we have to suck up and deal with

 

[EliteTahoe]

yeah, its just like the old VW Golf engines from the middle of 80's.
You hear the lifters knock for about 10 seconds.

 

[stbeverlin]

This knock is not to be confused with a lifter "tick". This knock sounds like a bad rod bearing, but it goes away in a few seconds after everything lubes up. A bad rod bearing will not go away, and gets worse as you accelerate. The Chevy dealer said the piston wrist pin gets dry as the oil drains off overnight and it takes a minute to circulate on startup. Could be.

 

[EliteTahoe]

a expensive way to get rid of this knock, could be to install a auxillery oil pump, that could pump up the oil pressure for 5-10 seconds before the engine cranks.

 

[Sepiroth]

No I dont think that installing an aux oil pump is the answer. The knock goes away as the internal warm up from friction and expand. A rebuild will cure the knock.

 

[boostaholic]

Maybe you need your valves adjusted :smilielol:

 

[Yuke2K]

Piston slap has nothing to do with the oil, quality of the oil, oil pressure, etc...it's the material the pistons are made out of.

The reason you get the noise only when it's cold, is because the pistons are aluminum. Aluminum expands as it warms, so when the pistons are cold, there is a little excess room around the skirt (bottom) of the piston. After the pistons warm a little, they expand and the noise goes away. If it only takes your truck 10 seconds or so, you're lucky! The piston slap in your engine isn't that bad. It takes mine between 30 seconds and a minute usually, sometimes a little longer if the temperature is sub 10 degrees or so. FWIW, the 2000 Camaro SS's/Z28's did this too...GM has pretty much written it off as an annoyance rather than something that warrents service work. It's not that big of a deal...it sounds much worse than it is, lol.

It won't hurt anything as long as you don't rev the snot out of your engine while it's warming up. If it starts making the noise ALL the time, regardless of temp, then you have other issues not related to piston slap.

 

[2001Yuke]

I have the same problem that has been getting worse for the last 4 months or so. It usually takes 10 minutes of normal idle to go away or .5 mile or driving. I have an 01 with about 67k on it BTW.

The newest issue is the Service Engine Soon light came on last thursday (4 days ago). Our service department was slammed friday and closed all weekend so I haven't been able to have it diagnosed. My oil pressure seems a little higher now. This evening driving home it was at 60 at 40 mph between 1200-1500 rpms.

The digital readout doesn't say "change engine oil" or anything like that, it actually just tells me my wiper fluid is low. Any ideas?

 

[Yuke2K]

Hrm...I'm honestly not sure bro. I wish I had a better answer for you. I can say that a solid ten minutes of warmup seems WAY excessive for PS to go away. My '00 is about to roll 101K, and the slap hasn't gotten any worse. I'd definitely get it checked out asap, and let us know whats up. Is yours a Denali 6.0 or the regular 5.3? I remember seeing some of your pics of the t-bar cranked and it looked like you had Denali rims and trim on the side...

Minor hijack for 2001Yuke:

Oh, and I'm getting my tires, ford keys and spacers installed this weekend, FINALLY, and all the labor will be free! And getting my tranny, t-case, front and rear diff and oil done for like $150, too. I'm stoked.

I'll post before and after pics when it's all done.

/hijack

 

[Big Tap]

As others have said, piston slap at cold starts is normal. I thought the same thing and became concerned the first time I heard mine do it, but it's just a fact of life on these engines. As long as it doesn't continue to do it after the initial 30-45 second start up time, you're fine.

 

[shadow]

I'm trying to find a thread relating to the piston slap problem inherent with the 99-2002 5.3 engine. My 2000 Tahoe started making the noise at about 70K and does it only on cold startup for about 30 seconds, then goes away. I've tried several good filter brands including Wix, Pure One, and Mobil 1, all with a good anti-drainback check-valve, but it didn't make any difference. I use Mobil 1 synthetic and have tried 5-30 and 10-30 viscosity, with no change.
GM says it won't hurt anything, but common sense says if there is a knock, its not good.
Any ideas or comments??

Lived with it on my 5.3L '00 Tahoe since practically new. There is a TSB for an O ring replacement for the oil pump as a potential fix (my dealer did this fix, but it did not work).

I recently switched from Mobil 1 5W-30 to M1 0W-30, and the noise has stopped. 0W will flow faster at start up, so I assume that's what has helped.

Might want to try that for you trucks, especially if you're already using systhetic oil, won't cost any extra dough.

 

[Sepiroth]

I will tell you that when I bought my truck, it had 5w-30 in it. When I did the oil change, I used 10w-30. It takes a lil longer for the piston slap to go away.