Piston slap

Motodox · April 7, 2016

Has anyone had any luck with getting rid of piston slap on their 5.3 ? My Silverado is a 07 with 80k miles and it drives me nuts every damn day. Pullin out of work it's embarrassing cause it sounds bad.

But I've been to multiple dealers and it's a different sound then a rod knock or upper noise. So it been determined as piston slap.

My dealer did a "upper engine" cleaning which involved some sort of solvent to clean the so call carbon build up on the Pistons and a oil change. They tell me the carbon build up create the gap between the piston and cylinder walls making the slap noise. Well that didn't change much if anything really.

So I was curious if anyone else out there hopefully has had any luck doing something to help with the noise. I seen some talk about royal purple syn oils helping but idk and that shits expensive. Anyways any tips or tricks would be great to hear thank you.

O_J_Simpson · April 7, 2016

Short of a rebuild, get used to it. Just keep driving it.

muddkatt · April 7, 2016

307,000 miles of piston slap when cold on the 2001 with no resulting problems. It does it worse with a fresh oil change (first 1000 miles) vs old oil (10K-15K miles) using Mobil 1. I have noticed that it slaps worse in colder weather.

white1500 · April 7, 2016

Piston slap or valve tick? My dads '06 4.8 had horrible valve tick and was resolved by replacing the oil pump itself or just the screen/seal (I forgot which one). That was about 2 years and she has been quiet as a mouse since.

partdoctor · April 7, 2016

This is caused by short skirt pistons. It does not effect the durability.

GM tried a "band-aide" by coating the pistons with minimal results.

intheburbs · April 7, 2016

My Denali slaps pretty bad when it's cold, so much so that my 17 year-old daughter noticed it. She sends me a text, "I think something's wrong with the truck." I ask her what's wrong, and she texts back, "It sounds like a diesel."

We just use remote start and let it idle 4-5 minutes before we drive it. Honestly, I'm not worried about it. It has 72,000 miles on it, and if I keep it that long, I fully expect 150-200k out of it.

Gurrzt · April 7, 2016

Sara (2001 Z28) & my 2013 Yukon Denali does this, the tick should go away within 30 seconds to a minute.

The LS series of engines all do this at one time or another.

You can try a thicker oil.

Motodox · April 9, 2016

Thanks everyone for the replies!! It's reassuring knowing others are going through the same issue and have really no detrimental side effects.

For the comments above saying theirs has ticked forever, mine sounds nothin like a tick. More like a tap or I like the comment that says his little daughter could hear it and it sounds like a diesel. That's exactly how mine sounds! It's very noticeable and annoying.

I will definetly keep driving it, wish there was a solution. Shoot even if I use my remote start it'll still have some slap when I pull out the drive. It only seemed to disappear quickly after driving it. For example I'll let it warm up for 5 mins in the drive and it'll slap for a minute or so when I pull off. Or if I just get it start it and drive off it'll disappear in 1min-2min of driving.

Has GM figured this problem out and fixed it yet? Because I'm thinking about going in at the end of year and getting a brand new 5.3 Silverado. And I do not want this slap to just deal with anymore. I know the 5.3 are crazy reliable my last one had 230k miles on it 2001 Silverado z71 and it purred like a kitten and I traded it in on this cold start slapping loud 2007.

Also I agree with the comment above saying the slap was louder with a fresh oil change I believe mine acted the same.

I wonder if syn. Oils make it quiter or conventional.

muddkatt · April 9, 2016

For the comments above saying theirs has ticked forever, mine sounds nothin like a tick. More like a tap or I like the comment that says his little daughter could hear it and it sounds like a diesel. That's exactly how mine sounds! It's very noticeable and annoying.

I wonder if syn. Oils make it quiter or conventional.

Mine sounds like a rod is knocking for the first couple of minutes.

I only run Mobil 1, so I don't know if dino oil would make it quieter, but I highly doubt it.

Motodox · April 9, 2016

Yess!! Mine sounds very similar to a rod knock for the first few mins. That's why it bothers me so bad, I could deal with a tick. I may have to try some royal purple ..... Maybe ..

anumber1 · April 9, 2016

The problem stems from the basic design.

Short skirt, forged pistons expand from their cold dimensions to their non slapping, operating temperature dimensions at a different rate than older designs.

Yes, they sound awful while warming up, It is not detrimental to engine life however.

partdoctor · April 9, 2016

My 2002 Yukon has 125,000 miles on it. The only thing I have noticed is the colder the ambient temp, the more noise it makes. I bought it used at 74,000 miles on it and it has not changed a bit. I have owned this since 9/11/2007. I occasionally tow a car so it gets some rougher use.

anumber1 · April 9, 2016

My 2002 Yukon has 125,000 miles on it. The only thing I have noticed is the colder the ambient temp, the more noise it makes. I bought it used at 74,000 miles on it and it has not changed a bit. I have owned this since 9/11/2007. I occasionally tow a car so it gets some rougher use.

My '99 has been doing it since 125K miles. 8 years ago.

300k+ on it now. Doesn't leak, burn oil, tick on the top end or anything else sugestting that it is worn out or even close.

Hammers like mad for a few mins when cold tho.

intheburbs · April 11, 2016

The problem stems from the basic design.

Short skirt, forged pistons expand from their cold dimensions to their non slapping, operating temperature dimensions at a different rate than older designs.

Yes, they sound awful while warming up, It is not detrimental to engine life however.

The way I understand it is that it's not just the design, but GM's method of building engines. In the past, the pistons were measured and, depending on where their diameter fell in the tolerance range, they'd be matched up with a block whose bore was in the same tolerance range. In other words, a piston on the low end of the tolerance range was matched with a bore on the low end of the tolerance range. GM stopped doing this, and piston-slapping engines are the result.

Separately, when I bought my '01 used back in 2005 (with 85k miles), I started running Mobil 1 full synthetic through it. It never really had a noticeable slap, but I did notice a decidedly louder tick when it was cold. That motor now has 223,000 miles on it, and it's still running like a champ.

Nanotech Environmental · April 21, 2016

06 1500 4x4 with 5.3. Owned since new, now with about 283,000km on it. I've never had any piston noise & have run Mobil 1 5w30 since new, doing all my own changes when the OLM says so - usually at around 12-14,000km.

The piston slap/knock is due to hypereutectic pistons that expand as they warm up, which is why it quiets down after a few minutes of run time and is worse in colder weather.. Annoying, but doesn't cause damage. Not sure why it affects some LS engines and not others.