arent the 4.3'* iron everything

Piston slap is fairly common in the 3.1, and 3.4 engines when cold, but thankfully mine doesn't do it.

Same thing with the 3800'*.

Definitely a common issue on the GM engines as well.

I have heard there is an issue with piston slap on basically all of the newer Vortec engines (2000+) and when I got my '96 Z71 it knocked like crazy when it was cold. I was pissed because I was not informed of the engine noise when I traded my little Saturn for it, the truck was already warmed up from driving when I test drove it and looked at it both times.

In the early Vortec engines ('96-?) I have seen mostly that the cause is either not properly sized bearings from the factory or carbon buildup on top of the pistons that causes cold spark knock. I also actually found a TSB from GM on the issue of the carbon buildup. Mine has 200,000 miles on it, is absolutely dead silent when warm out / all summer long, but as soon as the cold temps hit the dang thing sounds like a diesel for about three minutes.

One thing to stay away from for sure is the 2002 GM 4.2 I6 engine used in the Trailblazer and Envoy. We had one for about two months... Also sounded like a diesel when cold, took it back to the dealership and they informed me that those early I6 engines were known for the cylinder bore liner to come loose from the aluminum block and slowly slide down until it was down far enough that the rings would pop out over it at the top of it'* stroke then slam the liner down into the crankshaft, of course killing the engine! There is also a TSB from GM on that issue that if they have a secret 100,000 mile warranty that if that issue is the cause of failure before 100,000 miles they replace it for free or if it can be proven that the issue is present they will replace it also. Ours had 98,000 miles on it and the dealership didn't want to replace it so I dumped it for a trade on the '03 SSEi I have now.


Wow, yea... long basically useless post LMAO. Pretty much the piston slap / cold start knock is sadly fairly common in some new vehicles. I have heard the cause on the newer ones to be anything from piston skirts being too short, carbon buildup on the pistons causing cold spark knock, or the piston is loose in the bore allowing it to slap around some until it warms up and expands to fill the bore just right.

Guess that'* something I should be looking forward to?

my 350 vortec had the cold knock when i got it, too but it ended up being all the crap built up in the engine from have a intake manifold gasket leak and the PO not fixing it. after i changed them and cleaned the engine up for a couple hours the valley, lifters, and a bunch a white crap on the rockers. a couple oil changes and its quiet as new.

as far as the strait engine they have head issues too i wouldnt buy one