I'm new to the corvette world and i went out and bought a 05 6 speed.Here what i done.I was giving a buddy a ride and not being use to the 6 speed i was going to make a shift from 4th to 5th around 120 and hit 3rd instead.So know she is wounded.I knew i got either the valves or pushrods so i took it to the dealer for them to look at it since i got a extended warranty with it.They checked and it has no compression on #3 and #7 has 100lbs.They pulled the head and it has bent the exhaust valves and you can see marks where they hit the top of the pistons,but dosent look like it hurt them.I was thinking they could replace the valves and go back together.But hes telling me that the valves shouldnt have never hit the pistons and thinks someone had put the motor together wrong.It ran fine when i bought it so i know it wasnt put together wrong.The previous owner had put hot cam kit, comp pushrods and good valve springs.Motor has 51000 on it still had good oil pressure i drove it to the dealer it just had slight miss.So there wanting to put a new motor in it.I was wanting to keep it like it is.I know i'm a idiot for driving it like that and not being use to it so its alright to bash me.But what should a guy do dealing with the dealership.Thanks for any help.

 

Are you sure your extended warranty will cover the repair of a non-stock engine? On an over rev like you experienced it is quite possible to bounce the valves off the pistons. There have been a number of forum members that have done that.

You need to learn how to shift the six speed so you don't repeat that mistake.

Bill

 

Like Bill said, I doubt this will be covered under warrantee. When you shifted into 3rd instead of 5th, the motor mechanically oversped - probably >7k rpm. The fuel cutoff can't save you at that point. The motion of the car at that speed and the 3rd gearing ratio is what spun the motor that high. No doubt that the stock springs lost valvetrain stability and the valves hit the pistons.

If the mechanic told you the motor was built incorrectly then maybe its time to move on to a different shop. Personally, I would check both banks for damage and replace anything in question such as lifters, pushrods, springs and valves.

Call around to get pricing on repairing the top end... much cheaper than a new motor.

Sean

 

I would take it to an independent mechanic, not the dealership.

Why were you shifting to 5th at only 120? Does it have aftermarket gears?

 

Did you tell the dealer you mis-shifted? Or, did you play dumb and say you don't know what could have caused it? Under normal operation, all the way up to the redline, the valves should obviously never hit the pistons.

If you've got the Z51 (MZ6) transmission then you hit ~7600 rpm at 120mph in 3rd gear. You're lucky you didn't do more damage.

 

Not sure what gears it has in it.I just bought the car and they didnt say anything about a gear swap.He just told me that the guy put all z06 parts in the motor.If i remeber right at 70 mph in 6th its turning around 2100 to 2200 rpm.

 

I played dumb i just told them it had a miss in it.I bought the car and warranty from a dealership in hotsprings,ar.I took it to a dealership where i live.

 

The warranty sent a inspector out today there not going to cover the car because the aftermarket parts which i already figured.So there wanting to tear the motor apart and check everything replace any broken parts.Put new pistons since one has a little gouge where the valve hit.Put new valves and make sure the head is not hurt.For about 6000 thats parts and labor.Or they want 11500 to put a new motor in thats with me keeping the core and all the aftermarket parts.He said he would give a 12 month 12,000 mile warranty and stand behind it with the aftermarket parts if they do the rebuild.

 

The z51 package has the same gear ratios and rear end ratio as the z06. If they are genuine GM parts and they aren't blaming you for the damage then there is no reason for them to deny the claim.

If that is how you bought the car and they insist on not covering it, then your car was *never* eligible for coverage and they power you a refund of the entire purchase price of the warranty, which will at least partially pay for the repairs.

 

(The mobile site doesn't let me edit my posts.)

In the previous post I meant they owe you a refund on the warranty. My phone automatically corrected a typo and put power instead if owe.

 

I don't think you have stock gears. My Z51 runs about 2000 rpm in 6th at 80 mph. Based on what you say, it looks like you may have 4.10's out back. See below.

http://mysite.verizon.net/foofoo2/c6/

If you do in fact have 4.10's, that means you would have spun the motor even higher than the previously stated 7600 rpm. More like 9000 rpm!

 

if they will give you new motor take IT! tell them you will give them a few bucks for old motor

 

There not going to give me a new motor but i guess thats the route i'm taking.He says with a new motor gm will warranty it for 3 yrs or 100000 miles.And i'm keeping the old motor i dont think its hurt so i will just put valves in that one head and keep it for my 69 Chevelle.Not sure what size cam it has i know it has aftermarket gmpp heads i will have to get the number to check them has new valve springs and comp push rods.so i will save it for another project.

 

Well, that explains why they think the engine was put together wrong. You really should have just told them you mis-shifted and over-revved the thing. Then the dealership might have taken your side and helped push the claim through.

But with aftermarket parts you were pretty much SOL no matter what if the inspector could identify them. I'm betting the tech or service adviser told the inspector about the parts. I know my cam and valvetrain parts would look stock to most people unless they were really familiar with LS motors.

For what it's worth, the engine is probably fine. I'd probably just throw a set of new heads on it and call it good. Really no need to buy a new engine @ $11k. And a used LS2 long block isn't very expensive if you wanted to buy one for your Chevelle. You could probably have the heads fixed and buy a used LS2 long block for less than $5k. Take it to a good performance shop and get it fixed properly. My 2 cents, anyway.

 

I finally told the dealership here thats what i done and that i read on here that it would cause it to do that.But he still wanting to pull motor apart and check piston and bearings.I dont have any performance shops around here.Probably some in little rock,ar but thats 50 miles down the road and my work sechule i dont have much time.I just learn from my mistake and going to put the new motor in it and keep the old one.Then i will have 2 ls2 and it will make me be more careful and think the next time i wanna act stupid.Thanks for everyones input.

 

A dealer sold you a car with a warranty that you now disovered has aftermarket internal engine components? Why wouldn't you take it back to the origonal dealer and tell them to honor the warranty?

 

top of 4th on stock gearing, stock tire, z51 is 165 - tested

Sorry about your loss, I would put a forged motor in, while its all apart you might as well get more power out of it.

 

I honestly wouldn't let them take the engine out and tear it apart for no reason. If there is just a cosmetic mark from a valve hitting a piston, then I think it's a non-issue. I'm not sure why they would want to check the bearings. I think you have more to fear from someone that is not 100% qualified taking everything apart and re-assembling everything then just fixing the heads/top end. I'm worried by the fact that the tech doesn't realize that valve float from a severe over-rev can and will cause piston to valve contact.

There has to be a good LSx shop in your area. A flatbed can get the car wherever you need. A good performance shop will have seen this many times and know exactly how to proceed. This is coming from a guy who has been a dealership tech for 10+ years. But hey, it's your car. I'd rather spend some cash on a nice set of Trick Flow heads and make it better than ever.

Good Luck with it, no matter what you choose.

 

Actually, the Z51 has lower transmission gears than the Z06.

My math says 7600 rpm at 120 mph/3rd gear.

 

If you say so. In post 5 I said 7600 rpm. I used gear ratios I found on a post on this site (also had the same ratios for Z06).