Any other 07's owners with Piston Slap?

**Kickboxer** · 01-13-07 12:40 PM

We'll after 6000 miles, it's happened. My 07 has the dreaded piston slap. Thought they would have solved this issue with the new 6.2 liter issue but it's surely there for about 10-15 seconds on cold startup. Anyone else getting this?

**LLT** · 01-13-07 01:11 PM

I'm guessing if it's 6,000 miles you just recently did an oil change. Related to that perhaps?

I don't have piston slap on my current unit.

**nofinga911** · 01-14-07 01:38 AM

Originally Posted by LLT

I'm guessing if it's 6,000 miles you just recently did an oil change. Related to that perhaps?

I don't have piston slap on my current unit.

can someone tell me what piston slap is?

**LLT** · 01-14-07 02:25 AM

Piston slap is when there's too much clearance between the piston and the cylinder walls -- as the pistons go up and down, they "slap" against the walls.

**hcvone** · 01-14-07 06:19 AM

No problem with that in any of my 07's yet.

**BMBSALES** · 01-14-07 10:15 PM

they def make some noise when you start em up cold...

**Guyz1996deville** · 01-16-07 12:21 PM

Are the clearances of the wrist pin too tight, or are the cylinders the machined oversize? There is only one way to find out. I would address the issue and wait to see if the clearances change. Then it is on file to at the dealership..

**EXTadic** · 01-16-07 02:59 PM

Originally Posted by Kickboxer

We'll after 6000 miles, it's happened. My 07 has the dreaded piston slap. Thought they would have solved this issue with the new 6.2 liter issue but it's surely there for about 10-15 seconds on cold startup. Anyone else getting this?

Are you sure you're not hearing lifter tap? sometimes lifters will leak down while sitting and typically thats what most peolpe will hear ticking at start-up. Piston slap can usually be heard more clearly during engine deceleration. or when you snap the throttle open and listen as the engine revs down.

**hcvone** · 01-16-07 04:13 PM

I was getting piston slap when my last 07' exploded.

**caddycruiser** · 01-16-07 06:28 PM

Originally Posted by hcvone

I was getting piston slap when my last 07' exploded.

Yes, that was true...

While this issue doesn't seem completely out of place on this engine, given how it's been a constant problem with all of the GM LS-series engines since '97 (others too, but those are the main offenders), it's still a bit odd. They made design changes back with the last gen trucks around '03/04 and cured a lot of the problem, but a handful still had noise. After some mileage and over a year, our '02 Avalanche 5.3L would tap a bit at initial cold idle, but that was it--and our '04 Suburban 5.3L, with the design revisions, hasn't made even a single tick in 2.5 years and 43k miles.

Might be exacerbated by excessive cold or an oil irregularity, but still probably should be checked out.

Here's a good (well, not "good", but...) site with more info on the issue and also sound clips, for those of you unfamiliar with it:

http://www.pistonslap.com/

**BMBSALES** · 01-16-07 07:17 PM

That's A Great Site.

**caddycruiser** · 01-17-07 02:11 PM

Originally Posted by BMBSALES

That's A Great Site.

It doesn't portray things in the best light, but at least they have enough proper technical data that's easy to understand what the issue is. LOTS of the mentioned engines have had the problem, but at the same time an equal or larger majority out there also haven't.

That, and with the small design changes in '03/04, it really has become a much more limited thing to pop up. Case in point, like our '02 5.3L that had a bit of tap when cold vs. our '04 5.3L post changes that's never made a peep.

**becker500** · 01-18-07 11:39 PM

I have 10k on my '07 and I noticed lately at start-up in the cold it is starting to sound like a diesel. WTF! Based on what I'm reading here it sounds like it could be piston slap. Also, I back straight out of my garage then crank it to the right in drive and there is some sort of strange drivetrain noise as well. I'll let you know what the dealer says.

**ewill3rd** · 01-19-07 06:15 AM

This "piston slap" issue is more of a perception problem than a real issue.

The heart of the problem lies in the fact that it is a powerful, relatively high revving engine. If you compared a modern piston to one that "doesn't do it" from the 70's let us say, you'd notice some striking differences.
What typically prevents piston slap is the "skirt" of the piston.
There are twisting forces on the piston that try to spin it in the bore, the skirts on our pistons used to be quite long and did a nice job of preventing this tendency of rotation quietly. Over the years engineers realized that they can get better revs and smoother engines by reducing the mass of the piston and sadly the skirt was a good place for them to accomplish this, they shaved that puppy down to almost nothing and lightened the piston by quite a bit. (lower mass makes for higher revs also)
Newer pistons look really weird as compared to the Gen II engines of old. There is nothing really wrong with the engine, it just has a tendency to make some noise until the pistons expand. Bear in mind just one explosion from one cylinder at idle would be powerful enough to blow your head off.
Pistons are prone to expansion and contraction with temperature and are machined to very close tolerances taking this expansion into account.
When cold they are actually quite smaller than they are when hot, as the piston expands to "fill" the bore the noise will quiet down.
This is no indication of damage, wear, or impending failure as some would have you believe. It is actually an advancement in technology that consumeres demanded. Now that they have what they want they are not happy with the consequences of a slight noise on cold start up. If you try to install larger pistons, when they expand under temperature, they will stop moving in the bores and destroy the engine, a much larger inconvenience than a little clatter on a cold start I would think.

If you'd like GM to put quiet pistons back in your vehicle, get ready to pay more at the pump for gas and have a lower level of performance from your vehicle.
It is up to you. If you'd like the latter, please feel free to call your lawyer.

I am not trying to flame anyone, just stating what I know.
Please don't read any offence into my comments, none was intended.

**caddycruiser** · 01-19-07 11:20 AM

Great point to make, definitely. The only issue I could see is vehicles that have had the issue to an almost extreme issue where it sounds like it's going to detonate at idle and continues to clang and pop while driving--I knew a few people from the club with 5.3L Avalanches that did that, and ended up needing significant work.

But that falls into the category of just engine design/assembly irregularities overall. There was a "fix" a couple of years ago that seems to have cured most of the problem in a lot of the LS engines, with no detriment whatsoever to the performance, so that's also a point to consider.

The fact that some engines from the same "batch" can be silent and others sound like they're going to explode is probably the strangest thing, and what caused complaints and sites like that above to be started. If some are fine, then what the heck is wrong with mine, kind of thing.