Hearing about a Class Action Lawsuit Against GM

[Larry E.]

A group of Corvette owners has filed a class action lawsuit against General Motors, alleging that the company is not taking action to correct a problem with the 7.0-liter V8 engine used in the Corvette 427 and Z06 models from 2006 to 2013.The defect automotive lawsuit claims that GM is aware that the Corvette engines have excessive valve guide wear leading to engine failure and repairs, despite the company advertising the high quality and durability of the engines. Got a friend this happened to.
Comments?? Larry

[Ed S.]

Re: Hearing about a Class Action Lawsuit Against GM

Apparently true. If you google (or search) the term "class action law suit corvette engines" your search engine should pull up a long list of links about this issue (too many to list here). Most articles are short and say pretty much the same thing. From the articles it appears that there are only 19 individuals that are part of the class action at this time - would likely grow as news spreads.

[Michael J.]

Re: Hearing about a Class Action Lawsuit Against GM

Very interesting, they have also had numerous problems with their new C7 Z06, even getting a DNF at the MotorTrend tests:

http://www.corvetteblogger.com/2015/10/16/chief-engineer-juechter-responds-to-corvette-z06-dnf-in-motor-trend-best-drivers-car-test/

And some engines that had to be replaced that failed soon after delivery.

[Gene M.]

Re: Hearing about a Class Action Lawsuit Against GM

What does GM use for valve guides these days? The old stuff used the cast iron of the heads.

I realize the cam/rocker ratios and resulting lifts are greater today.

[Joe L.]

Re: Hearing about a Class Action Lawsuit Against GM

What does GM use for valve guides these days? The old stuff used the cast iron of the heads.

I realize the cam/rocker ratios and resulting lifts are greater today.

Gene-------

I don't know what they use on these Gen IV small blocks. Generally, aluminum head engines use cast iron or bronze valve guides. If they're using either of these, I cannot understand why there would be a valve guide problem UNLESS the guides are becoming loose. This is not uncommon on aluminum head engines with pressed-in valve guides. Often, when this occurs, engines are destroyed. However, GM used pressed in cast iron valve guides on 1987-96 Gen I and II small blocks and I know of no problem with these. Also, I believe that at least earlier Gen III small blocks used the pressed-in cast iron valve guides without problems. Therefore, unless there's something unique about the valve guides on the 7.0L engines, I don't see why there should be a particular problem.

[Gene M.]

Re: Hearing about a Class Action Lawsuit Against GM

Gene-------

I don't know what they use on these Gen IV small blocks. Generally, aluminum head engines use cast iron or bronze valve guides. If they're using either of these, I cannot understand why there would be a valve guide problem UNLESS the guides are becoming loose. This is not uncommon on aluminum head engines with pressed-in valve guides. Often, when this occurs, engines are destroyed.

Joe,
Is not the machining of the heads all CNC controlled? My guess is the press fit is not the issue as much as premature wear. I know that some times the metal alloys, and hardness (guides and valves) used are not friendly towards each other. Combine that with higher side loads and things go bad. I could be all wrong. I don't know anyone that is having guide issues to ask.

[Joe L.]

Re: Hearing about a Class Action Lawsuit Against GM

Joe,
Is not the machining of the heads all CNC controlled? My guess is the press fit is not the issue as much as premature wear. I know that some times the metal alloys, and hardness (guides and valves) used are not friendly towards each other. Combine that with higher side loads and things go bad. I could be all wrong. I don't know anyone that is having guide issues to ask.

Gene------


I don't know if PRODUCTION cylinder heads are machined by CNC. Most likely they are, but I don't know that, for sure. However, assuming they are, the CNC machining is only as good as the machining program. If there's an error in the programming, then there's an error in the finished part.

I believe the intake valves on these engines use a hard chromed stem in combination with cast iron valve guides. I suppose there could be a problem with the guide material/hardness. However, GM has been using this basic combo for a long time without problems. I believe the exhaust valves on these engines are sodium-filled. Just what problems that might engender I do not know.