I just got the bad news, I need all my pistions replaced because of Piston Slap.

What the dickens is Piston Slap?

 

Somewhere down the line GM changed the tolerance of the O.D. of the piston but did not inform the machine making the pistons. The piston is too small for the cylinder bore making the piston slap around. It somewhat sounds like a lifter tapping. :cheers:

 

Thats what it sounded like valve train rattle.

Thanks for the info

 

uggh... what year is your car
I was bugging my tuner about what sounded like a bad lifter and just plain loud valvetreain. I ended up pulling the heads off and changing out the lifters.

Still have the problem but it does seem to be getting worse & worse. Did yours start out quieter and then get louder? Is your car under warranty? Ay idea of cost from the dealer?

 

Its a 2001 coupe with an A4, 29,500 miles

Sounds exactly like the above reply -- valvetrain rattle. On Monday or Tuesday the folks from GMPP will take a look and decide if they will pay for the teardown and inspect. Then they will decide if they will pay for the piston replacement.

 

I don't have piston slap. Why do you say most 01,s have it. Did you do a survey? :auto:

 

solarisjedi, you know, it's funny you mentioned that it is worse after an oil change because that is exactly why I decided to take it to the Dealer. It sounded like it was going to come apart. Even the Dealer was suprised at the noise.

 

ttt

 

Wow, the times on some of the posts are all screwed up...

Cobalt Blue, I haven't driven mine much yet this year due to weather and being busy heh.
I changed all my fluids (engine oil, tranny, diff, clutch, brakes) a couple weeks ago to get her ready for driving weather. She didn't make too much noise when I cranked her up after changing the oil for leak test/drive around the block etc. The next day though it was noticeably louder at idle, almost sounded like the valvetrain (as most describe the noise) then cleared up after a couple minutes of idle and not really all that noticeable after warmed up.

Today is a different story. I took it for a 200 mile road trip. At cold start, it actually sounded like a normal engine, no slapping at all. After 100 miles down the road I pull into a gas station to meet some friends and I notice it is making a little bit of slapping at idle. Shut it down for a few minutes while getting a soda, sounded like a Mack truck when I started it back up... was loud for about a minute then just a subdued rattle

So, to make a long story short, it seems my symptoms are inconsistent. Sometimes it does it cold, sometimes hot, always at idle. Oil pressure is always good, and I'm positive this is not coming from the valvetrain.

I guess I'll be taking it to the dealer to see if they can sound probe it and what they recommend I do since I am out of warranty. *sigh*


[Modified by solarisjedi, 10:11 PM 3/21/2004]

 

Is this only an 01 issue. I have an early production 2000 (sept 99). I put some LGLTs on and here a slight tapping sound now...I figured the LTs just amplified the valvetrain noise. It doesn't sound like a MAC truck dieseling.

 

Mine is doing the same thing. '01 Coupe MN6 40K miles. It's had the noise since new, although when newer it sounded more like a small lifter tick. Mine got noticeably worse after a recent oil change. Sounds like a diesel when I first crank it up then it goes away (for the most part) after a couple minutes of idle. I'm leary of driving it now, for fear of damaging the cylinder walls.
I've read that a decarb procedure will help with the noise, but wont fix the root cause of the problem of course.

Unfortunately I am longer under warranty. I guess maybe I should write a letter to GM. I'd think they would want to make this right with all of us experiencing this problem.

 

Looks like most '01's are plauged by this. I avoid '01 C5s.

 

my 2000 does the same when started :cry

 

Well, it's still at the Dealers waiting on GMPP to decide if they will pay for new pistons. As a side note and as said above, it got worse after an oil change. That is what made take it in to be looked at. I had the oil change and it stated to rattle bad.

 

Just got mine back from the dealer after them having it for 2 days.

What they say:
"No abnormal noise heard at this time. Could not duplicate anything of concern"

I asked them if they heard the slap, they said they "thought" they could hear it, but then said they couldn't hear anything to be concerned about, it is just normal. yeah, right. They also informed me it was 3/4 of a quart low on oil... I said well yeah it has always used oil since it was new that doesn't surprise me, but that is still within operating range.

So it seems this dealer refuses to acknowledge that it is even making a slap noise. They couldn't offer any advice other than "if it gets louder bring it back".. of course they still charged me labor for looking at it.

I'm pissed off also on how my car was returned to me. Black grease footprints on my driver side floormat, sand, rocks and dirt all over it too, black greasy scuffmarks on my interior door rocker panel, dust all over interior... GRRR :mad

So in essence I just paid to have my car get greased up on the inside. yeay. Can't wait for that satisfaction survey you normally get after service to arrive in the mail.

:rant:

 

http://www.classcounsel.com./news/gm.htm

 

I had piston slap. I fixed it with a pair of kooks headers and GHL exhaust

 

Hi,
Piston slap is the piston rocking over from the minor thrust side to the major thrust side during combustion near TDC. It is worse when the engine is cold because the piston-to-wall clearance is greater so the piston can rock over further from side to side. The fix is a tighter piston-to-wall clearance or a longer piston skirt.

Chevy went to coated piston skirts in 2001 so they could tighten the piston to wall clearance. The coating keeps the pistons from scoring the cylinder walls when you abuse your engine by using high power when it is cold.

Good luck,
Steve

 

I am pretty sure the coating was a running change very late in the 2001 model year, some two or three weeks from the end of the run. My 2001 is from that time frame--I don't know if it has the coated pistons or not, but it makes no funny noises. It does use a little oil--about 1 quart every 2500 miles.

 

My '02 (built 10/01) has piston slap too. It didn't develop it though until about th 45k mile mark. I took it too the dealer too, and got the same "cannot duplicate customer complaint" :bs response.
I'm still under warranty though so I'll be fighting them some more on this :boxing :mad