drewz06

so I thought I was about to drop a valve but the noise cleared up the next morning.... stuck lifter maybe ?

stock engine supposedly... with 63k miles....

purchased cpo from s Chevy dealer, engine bolts still have what appears to be factory paint pen marks


drew

BigVette427

It's hard to tell in the video because the sewing machine sound is normal for the LS motors in the Corvette. The only way you may ever know for sure is to pull the heads. At that point, trash the GM LS7 lifters for Johnson 2110's (like GM does on the COPO Camaro 427) or at least, Morel 6504's. With your heads off, you may as well get the guides replaced, and with 63k miles on the springs, trash them for new springs, too. PSI beehives are top of the line.

drewz06

yeah i figured that would be about the response.... i've read plenty of similar threads saying the same thing...

the thing that threw me is it stopped making the pronounced tapping sound after about 30 miles....

here's what it sounds like now, though it does sound the same at first blush, but the first video has a slightly more pronounced tapping sound.


i can't take it apart yet, i still have a warranty on the damn thing, and the last time i thought there was an issue with the trans, the dealer told me they couldn't fix it until it actually broke...

looks like im driving it til it breaks again.... i did get a brand new t56 last time though

Z.06

as someone who has actually experienced and has fixed a stuck lifter, I offer the following advice:

• Continued driving will only deposit more shrapnel in your engine, making the repair more expensive, or maybe prohibitively expensive. Your warranty holder should be apprised of this truth. Address the problem as soon as possible to prevent catastrophic damage.
• Stuck lifters can be caused by excessive valve spring pressure or by camshaft case hardening issues. These problems may take years to surface. If the previous issues are at play, you should see distress on multiple camshaft lobes, not just the failure site.
• In my car, the lifter failure showed a tapping noise around 2000 rpm. This noise was not constant. After disassembly it was obvious that the problematic lifter could not be extracted from the top of the engine, per normal procedure.
• This necessitated removal of the problematic lifter through the camshaft bore, which is a very special procedure.

Mr. Gizmo

Apocolipse

Take the valve cover off and check. Takes 10 mins.

Pb82 Ronin

Nope. Single plate clutch.

RedZ4me

Of course - they want you to keep driving until broken but really they are hoping until warranty expires. 3rd party warranty?

Mr. Gizmo

drewz06

I appreciate the input! I'm a little leery about touching the motor, I really wouldn't want to give them any excuse to not fix it, or deny the claim.. a new engine is really expensive and I'm sure they would want to inspect the **** out of it before approving a new one

it is an after market warranty, so they file the claim and get paid for the hours, nothing out of their pocket...

I'm really not a fan of driving it in to the ground but they can't get paid if there isn't a problem they can make a claim against, so they don't want to touch it, since they would have to eat the cost of there was nothing wrong.

it hasn't made any odd noises since, and while I know that doesn't necessarily indicate a problem no longer exists, I'm stuck between voiding my warranty early, and/or potentially grenading the engine.

I've got 9k miles left on the warranty, I'm assuming a bad lifter would work it's magic before that.

also when they replaced the t56, I had them install a new stock clutch and slave cylinder since I didn't have to pay for the labor to pull the trans etc

Undy

Does your aftermarket warranty have a $$ liability limit?

"IF" there is a mechanical problem bits a metal could be coursing through your oil system, harming your oil pump and destroying bearings. T'wer me, Id pull the oil filter, cut the can open and inspect for metal between the pleats. That wouldn't be a warranty voider. You can make a better informed decision from there.

drewz06

good call, I'll be getting a can cutter here shortly.... and I didn't think about a limit on the warranty, looks like I have some fine print reading to do today!
thanks!

Bryan91SE

It doesn't sound abnormal to me.

stefuel

If you cut the filter open and find metal, go back to the dealer and show them. You say they only get paid for their time if they find a problem. Ask them for a estimate to check the camshaft and lifters and then decide if it's worth it to you to eat the labor if they don't find a problem. The metal came from someplace so odds are you wouldn't have to pay anyway.