[Z06] Took GM to court over dropped valve, and....
06-22-2011, 02:52 PM
#41
Race Director
OP~ Excellent post and pics! If you could take a macro pic of the valve stem ends, I'd like to see the wear they have. (Any "mushrooming?") Also, it surprises me that GM didn't spec the rocker faces to be machined. Maybe a cost issue? Me, being a tribologist, I see some problems with the rocker faces also, but will refrain from further comment until more examination has occurred.
2 piece exhaust valve stems will retain more heat locally, causing oil to varnish and reduce it's lubricating properties. This, (along with the side loaded, offset rockers) is likely a contributing factor to the valve guides becoming "bell mouthed." Once the guides are bellmouthed, the valve will not hit it's seat squarely, causing a "bending" type motion. Over many oscillations, failure is eminant.
I'd like to see the rocker faces (step) in an optical comparator...
2 piece exhaust valve stems will retain more heat locally, causing oil to varnish and reduce it's lubricating properties. This, (along with the side loaded, offset rockers) is likely a contributing factor to the valve guides becoming "bell mouthed." Once the guides are bellmouthed, the valve will not hit it's seat squarely, causing a "bending" type motion. Over many oscillations, failure is eminant.
I'd like to see the rocker faces (step) in an optical comparator...
06-22-2011, 03:00 PM
#43
Race Director
Like in this case a bill for a new LS-7 & shiester fees? Great value. 
A PE's license is his reputation, or at least it used to be before the Y2K 'PayGo' era. GM must've paid him well.
Seems GM's trying to bring back the good ol' fashioned cronism of the Roger Smith years. They're suceeding. GM's not more careful & pretty soon legal bills will outpace their UAW pension costs.
A PE's license is his reputation, or at least it used to be before the Y2K 'PayGo' era. GM must've paid him well.
Seems GM's trying to bring back the good ol' fashioned cronism of the Roger Smith years. They're suceeding. GM's not more careful & pretty soon legal bills will outpace their UAW pension costs.
06-22-2011, 03:52 PM
#45
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St. Jude Donor '12
I read the same thing. 
From what I am able to gather, seems like you're right.Settling doesn't mean that they are admitting to any wrongdoing, or fault.
He mentions in his prior thread that he was planning on using the small claims court system in his area which he stated has a maximum claim of $20,000.
When you figure that the MSRP on an LS7 is around 14K for us, and less than that for GM, then it made more sense for them to settle than to drag it out. Defending themselves, might end up costing them more. It's a little like totaling a car. Once you reach a repair estimate approaching a given percentage of the value of the car, it makes more sense for the insurance company to just total it.
Also, I have seen where usually a settlement includes an agreement not to discuss the case or the terms of the settlement, so it will be interesting to see just what the original poster can and does say in the second part of his post.
While I am NO engineer, I can say this.....when I bought my 'Z it was a few first's for me:
1) First time I have ever spent $75K PLUS on a vehicle....
2) First time I have purchased a new vehicle (have had numerous NEW GM vheicles-and ONLY new GM at that) and during the drive home from dealership be cruising along and listen "tick, tick, tick"......my 'Z had (5) miles on it when I got in it first time and tick tick started around 40-50 miles during drive home from dealership....noting it was VERY hot weather.
It has tick/tick ever since. Like airbus pilot stated, I have the container to do oil sample at next (second) oil change. Coming soon. My 'Z just turned 7400 miles. Using m 5-30 as what is on oil cap.
Every thread I have read all has pointed to the valve guides.....
Some of you smart guys out there, please, put your heads together and figure out what causes the guides to wear.....then let me know.....
PLEASE!!
I STILL love my 'Z.....but I sure would like to know what's up.....
To OP....so sorry that you (both) 1) had to deal with this issue and 2) had to go to the length you had to in order to get satisfaction.
It's a shame. These are really neat cars, but, at least IMO, should NOT have this sort of problem. I wish some of the engineers at GM would sit down and look at what's up and fix whatever it is that needs fix'in.
Anxiously awaiting part 2!!!! (Made me think of egash's issue few weeks back)
Last edited by tim414; 06-22-2011 at 03:55 PM.
06-22-2011, 05:09 PM
#47
With this decision GM eats the cost of a LS7 (probably costs them $3-4k to make one) plus the service tech fees for swapping a motor. Probably <$10k. We paid that for a day's worth of lawyer's fees in a patent lawsuit.
06-22-2011, 09:56 PM
#49
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Can I have my valves and guides inspected to see if I'm in danger? Would the action to be replacing as Vito.A suggested?
Having a cammed Z putting down 550, I'm a little worried about dropping a valve and I'd like to do the prudent thing and stay on top of this.
Having a cammed Z putting down 550, I'm a little worried about dropping a valve and I'd like to do the prudent thing and stay on top of this.
06-22-2011, 10:02 PM
#50
Burning Brakes
Some of the findings might be of interest to members of this forum. However, I have noticed in the last 20 months that there is a small group of individuals on this forum who like to mock the original posters when threads on blown engines appear. Accusations from missing shifts (I was accused of that), running engine low on oil (I was accused of that too), to being trolls (yes, I am finally posting photos for the first time on this forum) are only some of the examples. If you are one of those individuals, I suggest you skip this thread because I will have nothing nice to say about GM for the balance, and part 2, of my post. So you have been warned.
06-22-2011, 10:02 PM
#51
Le Mans Master
I just had my heads done by WCCH. My car has 25k, was bone stock, and hasn't been tracked. Valve guides had excessive wear. New bronze valve guides and SS exhaust valves were installed. Valve guide wear is a real concern and needs to be addressed by GM.
06-22-2011, 10:13 PM
#52
Last edited by forg0tmypen; 06-22-2011 at 10:16 PM.
06-22-2011, 10:25 PM
#55
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St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16-'17,'22-'23
Did you notice whether or not your rocker arms had the unfinished edge like the pictures in this thread? What year is your car?
06-22-2011, 11:02 PM
#56
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By itself, I don't believe the sodium exhaust valve has any issues. If the guide held up, the valve should have lasted a lot longer than the 11,000 miles I got out of my broken engine. However, the issue is a lot more complicated than that. I believe the size of the valve is too large for the heat path it provides for a high output enigne like the LS7, even in stock form. I will talk about that a bit more when I continue with my original post.
06-22-2011, 11:09 PM
#57
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Not really, since the wear is not taking place within the enclosed oil circulation loop. The wear mainly takes place below the valve stem oil seal. The open end of the valve guide goes into the exhaust port and leaves the engine.
06-22-2011, 11:26 PM
#58
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What surpises me is how Chevrolet's "independent" PE could so woefully misdiagnose what seems so obvious to even an untrained eye. And while I've nothing but respect for PEs of any discipline? Know all-too-well what one has to achieve in order to attain a 'PE' rating & the stamp? I'm now really wondering exactly WTH this PE saw justifying his report? That guy needs to retake the PE exam.
Thank you for your kind words regarding respect for professional engineers. I am ashame that this particular individual belongs to the same P.Eng association I am registered with.
His report contains multiple major mistakes and I was really looking forward to cross examine him on the stand. His report is the only investigation report GM has on my engine. I repeatly asked for a qualified GM powertrain engineer to look at my engine, but that never happened.
06-22-2011, 11:32 PM
#59
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Excellent post, I've been wondering about this the last couple weeks myself. stock 06 with 7500 miles on it, but im a poor schmo that cant afford to grenade an LS7. 
Looking forward to more details if we can get them.
In the other post you mentioned roller rockers would pretty much negate this issue, was that correct? Are any available as a direct stock replacement?
Looking forward to more details if we can get them.In the other post you mentioned roller rockers would pretty much negate this issue, was that correct? Are any available as a direct stock replacement?
06-22-2011, 11:44 PM
#60
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The following photo has an intake rocker on the left and the right one is exhaust. Note the difference in the tips. This particular exhaust rocker on the right has a wear pattern that straddles over the step. It doesn't show up that well with the flash photography. Why GM doesn't ground the whole width of the tip is a mystery.
[IMG]
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Last edited by hoefi; 06-23-2011 at 01:05 AM.