Piston slap LS3 - this is very interesting

would be cheaper to purchase the pressure gauge and line so u can check it yourself

 

Not to mention the fact that the dealer is probably not overly interested in providing you with evidence to show that your engine is failing early

 

yes I figured that but im also wondering how seriously they would take 3rd party information.

 

Are you saying the rings are gone too? The rings would hold the compression. It's only the piston moving a fraction in the bore when cold.

 

Although it sounds like going the long way around, presenting third party data is likely to be a very sure way to trigger the dealer into some kind of action. Probably starting with them repeating the test to verify it - at their own expense.

 

From what I read about the piston slap issue it's caused by poor machining and ovality of the cylinders. I doubt the rings can achieve a perfect seal in oval shaped bores and that would cause a drop in compression so a check sounds like a good idea to get an idea how bad the issue is.

 

No Im not saying that at all. Im wondering if piston slap is prematurely wearing the cylinder wall. If the cylinder is not wearing uniformly then I assume the ring would not be able to sufficiently hold compression.

 

I've been told the Piston is oval when it is cold and then heats up round whne at operating temp. Piston slap usually goes away when engine is at operating temp. The Bore would be a lot stronger than the alloy piston.

 

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I don't think a piston can change its shape like that. It just expands and contracts with engine heat but shouldn't change from oval to round and back again. Well not unless they are really crap pistons with too much machining on one side or something like that, doesn't sound good either way. I think I'd be looking into a proper remachine of the block to be honest.

 

A long time ago I had issues with a aluminium block after investigating I believe it is green blocks which cause the oval bore

 

Quick search found this. I have also been told this.


The piston is designed to be an elliptical shape when cold. As the engine reaches operating temperature, the piston pin bore area expands more than other thinner areas of the piston.

Why is piston slap loudest with the engine cold?
According to Stothers, “The reason pistons with more cold clearance make more piston slap noise is that when the piston moves from the minor thrust side to the major thrust side at TDC, it can gain more velocity before striking the cylinder wall.

 

Good evening, I have just joined the just commodore group. I have the LS3 Calais 2017 September and it had the piston slap. I reported and was told all good. It then got worse and lasted longer so different dealer had them listen to it. A recording was sent to Holden. This was last week. So on my work today after driving for 20 minutes the NO OIL PRESSURE warning came on Stop the Engine. I did, I then started it again, piston slap there now. Drove to work rang Holden and took it dow, no oil pressure and no noise. Have told them it is there until fixed. I brought new in 2018 and have done 48,000km. It has had new fuel pump, filter and fule pressure switch already. Love the car but OH OH.

 

Yep^^^^^^^^