Cold Start Up Knocking Noise

[dbailey]

The knocking noise that apparently is inherent in our 3.4 seems to be getting worse as time goes by. I've prolly got 55,000+ miles on my 2000 Coupe and it really seems to be getting bad. Has anyone actually had their engine blow or anything and it be realted to the piston slap or whatever it is that causes the knock right when you start it up? The sound goes away after a few minutes but right at start up it's pretty obvious. Wonder if a Jasper crate motor is any better? Thanks for any opinions/experiences.

[Wildman]

If its more of a ticking noise, thats most likely the lifters. That noise happens on mose of the 3100 and 3400 motors. Not really a problem, just an annoyance. I have 67000 on mine and it does i on every cool start. As far as piston slap, if it was that, I would think that you would be having major enine issues at this point if that was happening. My engine has been apart but ony because the dealership dropped something in my intake for cylinder #3 when they did my lower intake manifold gasket. They replaced the head and piston, and have had the thing almost a month cause they cant find this darn loud metal tapping noise. ANYWAYS, sorry for the rant there, but regardless, its most likely the lifters.

[dbailey]

Thanks for the good info. It is really more than a ticking noise. It's more like a rod knock/wrist pin kinda sound. I recall reading something somewhere where it was said that GM was attempting to repair it with a teflon coating or something that supposedly temporarily fixed the noise only to reappear after the teflon wore down. Ever heard of that anyone? Hope your problem gets fixed ASAP!

[King Asoka]

I have the piston slap in my 3400. Its only on start up. I let my car warm to atleat half or full operating temp before driving. My dealer said you could get the pistons coated witht he teflon but like you said it will just wear off after a while. I dont think u will have any other problems becasue of it, as long as u warm her up. The explanation i got was that the pistons are slightly too small for the cylinder, so until they warm up and expand a little they will make that god awful noise! Not much you can do. I figure down the road i will do a complete rebuild and fix the problem then.

[bigd6983]

I know this doesnt seem like it would fix it but I was having the same problem, only when it was cold and also it was noticable in low rpms. i recently changed my spark plugs and I dont hear it anymore.

[alerochick242]

Interesting. Mine makes a little ticking/knocking noise when I first start it up, but then it goes away after a while. I used to worry about it, but I have noticed that many cars do this, including my fiance's Z-71 (with the 5.3L V8). He told me that it might be the valves or lifters or something and that when they finally get some good oil flow to them (after the engine and oil pump have been running a while) they stop making so much noise.

[jturkey69]

not much you can do with piston slap at this time, especially since there isnt anyre-call, were all SOL...mine does it to a bit too, ...

.on a side note...if someone was actually gonna pay money to have the pistons teflon coated, this would mean a re-build, which any competent shop will set up the motor a lil tight, so there wouldnt be a prob with piston slap.

[Redog]

I get that ticking nosie too. I just thought it was because my car idles faster since I got the manifold done. It idles at 1250 until it warms up. I usually let it go to about 1000, then I go

[dadirtybulldog]

i have the same noises at startup.. i have 104,000 miles on my 99 'lero... i noticed the noise around 85,000.....??????????????????????????????????????? ?