Blauenstein

Hi all, please I need some Pro US forum input from you guys...My brother who lives in Eurpoe has a 1999 C5 that from one day to another makes a terrible cold start rattling noise. It sounds like a diesel engine shaking a box of nails. Miraculously after 2 minutes the noise disappears and it sounds and works normal. It only has 100k miles and he uses 95 octane gas. Also he tried to use a lower viscosity oil one dealer recommended. The European Corvette forum thread specifies various issues like a problem with the knocking sensors, valve or hydraulic issues, oil pump but there is no clear mentioning how to diagnose and fix it or whether this may cause short term engine issues. Your input is highly appreciated. Thanks again and regards, Peter

lucky131969

Do a search for piston slap........

Banditz

Yep..piston slap. Mine as well as many other's out there do this. Just drive it and be happy with her.

Blauenstein

Thanks Lucky I think that what it is

Blauenstein

Thanks for your feedback I still cannot believe this noise happens overnight rather than getting gradually worse

RonSSNova

Mine does the same. It sounds terrible.
So I turn the stereo up.
I run this thing to 6800 at the drags.
I doubted folks too, but it shuts up and is fine after about 2 minutes.

Once the pistons expand to the bores.

Ron

Blauenstein

Thanks Ron I am just bumped it is doing this with less than 100K miles while other go 200K without issues

F-2

Some do it some don't. Luck of the draw.

KillSwitchNY

Agreed. Cold start piston slap. Has to do with the contraction of the aluminum pistons when cold, which is why at operating temp it goes away. My 2000 Camaro LS1 has this same noise and 150k miles. I drive it hard with no issues. It just makes you cringe when first started, that's all.

Blauenstein

Thanks guys that makes sense

NukeC5

Yep, piston slap. I get this too.