dabrazil

When cold, upon startup and in gear there is a noise like a bearing knock. Knock goes away after 2 or 3 blocks. noise seems to be gettting louder. I park the car on a slight incline with front end down. Have taken to dealer several times and never here this knock. Does anyone know what this might be?

rcknusa

I have a 2000 coupe with A4 and hear the same thing until I get out of the subdivision. I have read on other posts that for our year model it is common (don't remember why though) and almost everyone who had the problem said the noise went away after it warmed up a little. I did not do a search but if you type in engine knock on the search you will find a lot of posts about it.

bassspring

I have a 2K vert and its made that same knock sound since I bought it 2 years ago seems to be worse when I get close to oil change time. I think this is whats refered to as piston slap and they all do it. Bassspring

b2z4me

My 2000 Vert also knocks on cold startup. But knock only seems to last about 2 blocks, maybe a minute or less. I suspect it is piston slap which I have heard is a common problem, but not a serious one. Otherwise the car runs great. I'm considering going to 10W-30 Mobil-1 on my summer oil change to see if that makes a difference. Box stock auto ran 105 / 13.7 1/4. Uses no oil & seems OK otherwise.

speedsk899

Doesn't sound good. I have a 99' with 108000 and have never heard this. I don't think that I would write it off as "Common". Not with a knock that sounds like a rod. Are you sure it isn't valve train noise?

bestvettever

Hi, I've heard that quite a few of the c5's up to 2001 have a tendency to make a tapping or knocking sound, some from day one, on first startup of the day. My 03 doesn't but my 02 chrysler 300m has a tendency to . To me it sounds like valve tapping. I found that using a much better OIL FILTER with a good check valve in it cuts down on it dramatically, to the point that I seldom hear it anymore, going back to a lesser filter brings it back again. Don't know if that will work for the vette , but it's worth a try. Although it may be piston slap. I read somewhere that GM redesigned the piston skirt after 01.
Good Luck.

dgrant3830

Is it a knock down low or a tap up top?

NocarbutaVetteforme

Sounds like the notorious piston slap. Mine has had it for it's entire life. There is/was a TSB on this I believe. I think GM had a problem with their trucks doing the same thing but I can't recall off hand. My friends cars all have this as well. I have noticed that it changed depending on the oil I used. But then again that could have been attributed to my steady loss of hearing.

dieseldave56

Very common, not to worry. Read:http://forums.corvetteforum.com/show....php?t=1950088

donaho

I own a 2000 FRC with 34,000 miles. As of now I have not heard this noise. I hope it stays that way. I use 5-30 Mobile 1 with a Mobile 1 filter.

park83

All I hear from mine is a tapping on cold start that sounds like valvetrain noise. My last car was a DOHC that I put heavier valve springs and Ti retainers in, so im used to lots of valvetrain noise.

speedsk899

I use 10W-30 Mobile due to high miles and have never heard it

dabrazil

Thanks for the info. my last oil change was suppose to have a oil filter with a check valve. will look at more filters.

David426

pistonslap.com.
most of the c5s as well as other GM engines have it and it is perfectly normal.. Its the nature of the beast. goes away after engine is warmed up.. I noticed mine after 3 months, Most people will say they don't have it but have never really paid attention to the issue or are in denial. The issue was supposedly resolved on 2002 models, however many folks still report piston slap. The noise is irritating but I have just learned to live with it for a few minutes.. the borla stingers help too!!

dieseldave56

..........stated at a press conference at Irwindale in 2002, that because of a limited number of customer complaints , a new piston was introduced to production in mid April of '01 that resolved the issue. This piston has a anti-friction coating ( the first Gen 3 engine to use this technology ) and that the pistion to bore tolerance was reduced. No measureable power loss was seen. Addressing the piston knock anomoly was more to please the possible complaints rather than being a performance or durability issue.

As with most all advances, Corvette leads the way to passing technology to the rest of the GM line , as most GM truck engines now enjoy this same anti-friction piston design.

One Nut

my duramax knocks my tahoe did it and my 01 c5 does it slightly when very cold also slight lifter noise. All said to be "normal" my nephew works for GM and has stated that the c5 is normal per his profession ASE certified monkey. His fix is to crank up the tunes for first 2 miles of driving then lower to comfortable listening level.

T-TOP TOM

When I bought my S10 with 113k on it, it had piston slap when cold. Now has 226k and still have the same piston slap untill warmed up.