vettnut

Do all the 427's appear to have the same head problems?
I am considering a 2013 Collector edition with the 427 for purchase.
I assume they all have this potential problem.
Had to ask.
Thanks

b4i4getit

Post this in the C6 Z06 forum and you would stand a better chance getting an answer.

FastestBusaAround

2 Things:

1) This is not the C6 forum, so you need to post the question there for more/ better response.

2) There were only a few valve guide issues IIRC, and it wasn't across the board. I had an '08 C6 Z, put 50K miles on it, took it apart to check for the problem and it was a clean and perfect as brand new. There were some reports of the engine grenading as a result of this issue, but it was a very small percentage...not enough to worry about IMO. A quick search on Google however does indicate that GM is being used over this by some owners...

BJ67

You are correct, they all have the potential problem. Some cars have gone into 70k mileage range with no issues.

Bill Dearborn

There is a problem with valve heads breaking off and dropping into the cylinder. Sometimes it grenades the engine and sometimes it doesn't. My engine didn't grenade it just quit. GM replaced it under warranty as almost all of the internals would have been replaced and it was cheaper for them to replace the engine.

There are a lot more people complaining about valve guides than there have been people who have actually had a failure. Nobody really knows if loose guides cause the valve drops seen on the LS7 but when you look at the data. Actual valve drops Vs So Called Guide wear the data doesn't correlate. For instance in engine failures caused by valve drops about 90% of them were exhaust valve drops but in the so called valve guide wear threads the incidence of excessive intake and exhaust valve guide clearances is split right 50/50. If the guides are the cause of the problem it seems like there would be a lot more intake valve drops than there have been.

Bill

383vett

My 08 had the head replaced at 23,000 miles due to excessive guide wear. Same thing with a buddy of mine's 08.

Les

That would be me- at 26K miles if memory serves and they were way out of spec. Run that way long enough failure will occur. Thankfully folks became educated about it and I'm sure a lot of engines were spared an ugly fate. Premature guide wear is far more common than grenaded engines. Anybody who tells you that premature guide wear is not a problem is not well connected with reality.

AzDave47

I just had the C6 Z06 heads done at 46K miles. I'll know in a week or so if the guide wear was outside GM spec. I did the work including HCI before my GMPP warranty expired. I would not run an LS7 without warranty unless the heads had been done by a competent machine shop. Do all LS7's have the problem - no. But is there only one or two MY cars that have the potential for the problem, no, all of them potentially have the issue. GM doesn't accept the wiggle test any more, but if you have the wiggle test done and it indicates the guides are OK, they are. If they indicate a problem, the heads need to be pulled to verify whether the guides really are worn outside spec or note. GM seems to have found quite a few heads that failed the wiggle test and then were replaced under warranty, but measured within spec when the heads went back to GM. Also some brand new heads have had the valve guides not be concentric with the valve seats by more that the excess wear spec.

Most of this info is over on the C6 Z06 chat board, OP.

johnglenntwo

I recall its dyno and the valve (stem too) falling out of the muffler, classic!

3 Z06ZR1

Buy it you will be fine!

JWingo

I previously owned a 2008 Z06 and then a 2013 Z06. Both 7.0 or 427 cid.

I only had around 20k on the 2008 and got rid of the 2013 with around 4k on the clock. So my experience may not reflect that of the higher mileage cars. I had no issue.

Both were very good cars! The 427 is a torque monster! If it's under warranty, drive it and don't be concerned. If it isn't, I'd keep around $2k and send the heads to a reputable rebuilder and have the machining corrected. Even though GM has backed away from the "Wiggle" test, I feel it's still good enough to get an idea if the guide is shot or not. I mean if you can move the valve stem .025 and you're set up to measure as close as possible to the top of the valve guide near the seal, I'd say that one needs to be serviced.

BJ67

Exhaust valves are the culprit. Thin wall sodium filled. the not so precise valve guides make the thin wall Valve stems even thinner, The head of the exhaust valve breaks off. The intake valves are solid and don't break.

AzDave47

You need to read thru the threads on this, a good number of intake valves have lost their heads and ended up in the intake manifold on occasion.

While there was no part number change, there appears to be a change in the exhaust valves somewhere in the 2008-2009 production time. Even the older exhaust valves did not have problems if the valve guides were run within spec and they were concentric with the valve seats (not always in spec even on new replacement heads re concentricity).

JoesC5

Many people (especially in the C7 section) use the excuse that a problem is not really a problem because people only tell about their bad experiences on this forum, thus the problem is magnified out of proportion. In other words, only a few lost engines have occurred, according to them and the valve problem really doesn't exist..

Well, I just got a letter from Terry M Inch from GM, telling me that the warranty on my 2009 Z06 has been extended to 10 years or 120,000 miles(whichever comes first), for the problem described below.

How many reported instances have any of you heard of, on this forum, of a diagnostic code being set and the service airbag light being illuminated, due to the seat's side airbag connector being damaged/disconnected because it is dragging on the carpet?

I don't recall any such postings from CF members on this forum complaining of this problem, yet GM apparently has had enough service problems crop up, that they are extending my warranty and I have never had a problem with the connector under the seat being pulled loose and setting a code, etc.

Maybe, just maybe, this forum is not an accurate means of determining if a problem with a Corvette exists or not. Like the LS7's valve problem.

z06clif

I got that letter 2 weeks after I reached 10 years. So i dont know what good the letter did

Clif