Piston slap in 04 ls1's

[gcmlear]

Been reading old posts re piston slap on gm engines and wondering just how prevelent this is on the newer ls!s. Any improvements on the 04's by chance? How bad does the noise have to be before gm will deal with it as a warranty issue. Also does this show up right away on new engines or does it develop later with miles. Thanks for any info..

 

[c4c5specialist]

Been reading old posts re piston slap on gm engines and wondering just how prevelent this is on the newer ls!s. Any improvements on the 04's by chance? How bad does the noise have to be before gm will deal with it as a warranty issue. Also does this show up right away on new engines or does it develop later with miles. Thanks for any info..

HI There,
There are alot of variables to the piston slap issue.
First, it will NOT in any way create an unreliable engine. IT is strictly an annoyance.

Second, in late production 2001, all Gen 3 engines were equipped with polymer coated pistons, that reduce the piston to bore clearancing in the engine. This virtually eliminated the piston knock concern.

Third, this is mostly due to the fuel formulations that create carbon deposits on the piston crown and the ridge going to the first compression ring land. This ends up creating a rocking motion of the piston, until the piston skirt gets warm and is tighter in the engine.

You have a 2004, so I do not believe that you will have a problem. If you end up having a concern, you might try a bottle of 12345104 or Techron to burn up the carbon that would be creating the condition.

Allthebest, c4c5

 

[gcmlear]

Thanks so much for a informative reply, regards

 

[Stosh]

Noise

HI There,
There are alot of variables to the piston slap issue.
First, it will NOT in any way create an unreliable engine. IT is strictly an annoyance.

Second, in late production 2001, all Gen 3 engines were equipped with polymer coated pistons, that reduce the piston to bore clearancing in the engine. This virtually eliminated the piston knock concern.

Third, this is mostly due to the fuel formulations that create carbon deposits on the piston crown and the ridge going to the first compression ring land. This ends up creating a rocking motion of the piston, until the piston skirt gets warm and is tighter in the engine.

You have a 2004, so I do not believe that you will have a problem. If you end up having a concern, you might try a bottle of 12345104 or Techron to burn up the carbon that would be creating the condition.

Allthebest, c4c5

C4C5,
I have an 04 with 1000 miles and when I first start it it sounds like a metalic knock from the engine compartment. I can actually hear it better from inside the car. After it warms up it goes away. Not a mechanic but it may be piston slap, has the right frequency.

Should I worry?
Stosh

 

[smook]

As per my info,


01-02. I had a 02 with piston slap. Then my 03 and now 04 are fine.

ENJOY THE RIDE.
Bill.

 

[U.P. John]

I have an '04 - runs perfectly. And I know exactly what it is because my '02 Tahoe has it. I just wait a minute till the oil pressure drops under 80, then it goes away.

 

['04 Torch Red]

HI There,
There are alot of variables to the piston slap issue.
First, it will NOT in any way create an unreliable engine. IT is strictly an annoyance.

Second, in late production 2001, all Gen 3 engines were equipped with polymer coated pistons, that reduce the piston to bore clearancing in the engine. This virtually eliminated the piston knock concern.

Third, this is mostly due to the fuel formulations that create carbon deposits on the piston crown and the ridge going to the first compression ring land. This ends up creating a rocking motion of the piston, until the piston skirt gets warm and is tighter in the engine.

You have a 2004, so I do not believe that you will have a problem. If you end up having a concern, you might try a bottle of 12345104 or Techron to burn up the carbon that would be creating the condition.

Allthebest, c4c5

Or maybe a bottle of BG's 44K...its the best on the market....I used it in my '95 and it worked a miracle with the carbon deposit issue...

 

[Greg Gore]

Piston Slap

Piston slap is not a concern in an otherwise good engine and I would personally not take the engine apart to fix it unless it was really objectionable. An aluminum piston contracts when it cools down so the running clearance will be greater in a cold engine. It needs enough clearance so that it can expand and contract during normal temperature cycles and perform its job which is to seal and transfer combustion pressure and perform properly for an acceptable life. Piston slap results from piston to bore clearance that is sufficient to produce the noise. OEM likes to employ cast pistons where ever possible because they can survive with tighter piston to bore clearances causing them to run much quieter but costing a penalty in increased friction. Cast pistons have integral steel thermal struts that control diminensional change during warm-up so the specified piston skirt to bore clearances can be made intentionally tighter. Forged pistons expand and contract more, require more running clearance and are somewhat noiser by design but they are stronger and run better. Engines that have excessive piston slap have more than the piston designer's specified clearance and the only fix is to replace the pistons to reduce the piston to bore clearance. Piston slap is usually more pronounced right after a cold start and should diminish as the engine reaches operating temperature. Piston slap is also more noticeable at idle and right off idle under light acceleration. If your engine does not exhibit these traits you have something besides piston slap. Piston slap is really not all that bad. If you could put a quiet exhaust on a good racing engine you would hear a lot of piston noise. Increased piston to bore clearance reduces friction and is specified intentionally for purpose built competition engines. As C4C5specialist said it is only an annoyance but if it bothers you GM does have a bulletin and a piston to fix it.

Regards, Greg

 

[CosmicTrucker]

My 04 has been slapping since 7500 miles. I'm not happy, and neither are my local Chevy Dealers due to my raising hell. A couple buddies own C5's, and their cars don't knock one bit.

How anyone working for GM can be proud of this and in the same breath swear that it's "Perfectly NORMAL" for one of their flagship engines to knock like a diesel is beyond me.

 

[c4c5specialist]

My 04 has been slapping since 7500 miles. I'm not happy, and neither are my local Chevy Dealers due to my raising hell. A couple buddies own C5's, and their cars don't knock one bit.

How anyone working for GM can be proud of this and in the same breath swear that it's "Perfectly NORMAL" for one of their flagship engines to knock like a diesel is beyond me.

HI there,
Then you should find yourself another dealership.
Allthebest, c4c5