Piston Slap... Should I Worry?

GMCanuck · May 4, 2017

So I've started hearing noises on my '06 Sierra, 5.3 with approx. 113K miles on it. After visits to a Dealer and a specialty engine shop, I have been told it is piston slap. Looking around on Youtube and various other resources, I find that this is an EXTREMELY COMMON issue with these engines - especially at cold start.

Difference with mine... it never entirely goes away, even at operating temperature. It certainly is quieter, but is always there. The fact that it does get quieter seems to confirm piston slap, rather than rod or main bearing noises, which I understand are pretty consistent, and do not change with engine temp.

Aside from the noise, the engine seems to run well. Will confirm any power loss later this summer when we start pulling our camper again.

So the question is... should I be concerned? I've been told (and have read) that this is not that big a deal and just to keep driving it. Would you folks agree with that?

We are actually about to hit the road for a 2-week road trip (no trailer in tow) out to the west coast. Just looking for some additional peace of mind.

Thanks.

GMCanuck

O_J_Simpson · May 4, 2017

I would be more concerned if my GMT 800 5.3L was not knocking. GM calls it normal engine acoustics.

GreenGreen · May 5, 2017

I had similar problems with my over 200,000 mile 5.3L it may be just the hydrolic lifters, mine would lifter tick pretty bad on startup but it would quiet down after it reached about 210 on the temp gauge, it would sometimes come back on acceleration but not always, don't be concerned about it, it is super common. I have almost double the miles with the ticking and it is still good. I do notice when I run higher higher grade oil (royal purple) or other high quality synthetics it isnt so bad, and in the summer months I run 10w30 amd I notice a small diffrence with that too. Here is a video of a newer 5.3 with the tick:

Hope that restores some faith in the o'l 5.3

GMCanuck · May 5, 2017

... Here is a video of a newer 5.3 with the tick:

Hope that restores some faith in the o'l 5.3

Interesting video... so after adding a container of STP treatment into a 5.3 Chevy, it turns into a Ram Diesel???

I do still think my noise is more bottom end related, since it is loudest from underneath. I'll keep an "ear" on it and see what happens. Hopefully all goes well, as we add a few thousand miles on it over the next month, heading to the coast. We'll see...

Nanotech Environmental · May 7, 2017

I would be more concerned if my GMT 800 5.3L was not knocking. GM calls it normal engine acoustics.

FWIW my 06 5.3 has never had any slap, or knock. Has a very slight lifter tick sometimes. Almost 200 k miles on it.

I have no idea why some do it and some don't.

For the OP, if it didn't knock before and now it has started knocking at 113k miles, I'd personally have trouble accepting the diagnosis as piston slap. Have you owned it since new?

Podor · May 7, 2017

When you Google piston slap and start typing the "5" in 5.3, the 5.0 Coyotes and 5.7 Hemis pop up along with the 5.3. In short, all modern engines have some degree of piston slap. It the old days, the piston pin was offset to minimize the rocking of the piston pin at TDC and the tolerance between the piston and cylinder wall was tighter. That added mass and additional friction once the piston swelled with heat. Now the tolerance is more free to cut down on friction and the pin is close to center to reduce the mass of the piston/pin assembly. The byproduct is a higher revving, more powerful and more fuel efficient engine, with more piston slap at cold start up. GM started going with full floating rist pins and coating the pistons as the Ls progressed, reducing piston slap significantly.

I've had a 00 Suburban with close to 200k, a 03 Silverado I bought new, a 05 Suburban and a 07 Yukon, all with 5.3l. The 03 (from day 1) and 05 had piston slap, the worn 00 and 07 didn't have any. Some make more noise than others. If it doesn't go away once it warms up, you may have other issues. No engine is completely silent.

mawint · May 8, 2017

My Avalanche has done the slapping/tick noise on cold starts for the last few years and quites down once it warms up. As annoying as it is, it hasn't caused any issues.