Tech

I didn't call you names. In your first thread (that I saw at least) on the topic, I defended you. I'm not a "usual suspect". There are plenty of people in this thread who have attacked me just like you feel you're being attacked. Over the same topic even.

Tonylmiller

I will let people evaluate it for themselves.

ZO6JSB

Well I have a 2009 Z and it has 300 miles on it. Yes 300 miles. Took to AHP we’re they found multiple valves were out of spec.

nuke61

Even though they are outside of GM's specification for acceptable guide wear, and even according to GM (back when they were doing this) it would require head replacement, it doesn't count because:

• You have to drive it until your motor breaks
• You have to prove it was the valve that caused the breakage
• You have to document it on the internet

MTPZ06

I believe it...its been documented that OE replacement heads taken right off the GM parts shelf have tested to be out of GM tolerances.

Tha shu

I purchased a 2008 Z06 with 14.5k miles back in October of this year. At the time, I also purchased a warranty for 3 years/36,000 miles. It's a full comprehensive warranty that lists basically what isn't covered versus what is, as it's that comprehensive. I didn't see valve guides on the "not-covered" list, but I'm not going to lie I'm worried that if something should happen they won't cover the $14k+ for a new engine.

Is there any other type of language in the warranty I should look for to make sure the engine would be replaced if a valve were to drop? I just don't want them to come back and tell me that the valve guide is a normal wear and tear thing I'm suppose to have checked.

Would it be smart to cancel the warranty and just get the heads done?

Tonylmiller

According to GM, the model years 2009 - 2011 were affected by a machining error. Whether you choose to believe them is up to you.

If that is the case, they were probably bad before they were put on the car.

Tonylmiller

It is probably cheaper for them to fix the warranty claims than it would be to fix over 30,000 engines. Right or wrong, they are in business to make money and after your warranty ends, you will probably be on your own.

MTPZ06

Whats the name of the warranty company? Some are better than others. My heads were done at AHP under my GMPP warranty. A warranty is never a bad idea as it covers many other things on the car as well...but some can be a crap shoot when it comes to the heads or engine replacement.

We saw an instance not to long ago where a warranty company was trying to take a page out of the healthcare book and calling the dropped valve a "preexisting condition", therefore not covered since there's no way that the valve guide had worn out from the time the policy was purchased.

MTPZ06

I believe in the machining error...not the date range. There's brand new heads produced well after 2011 with zero miles on them that have tested out of tolerance.

Tonylmiller

That being the case, if they specified those specific years, they must be pretty bad. I think a person could make a good case for having GM fix that on those model years. Doesn't mean they would do it, though.

Tha shu

I don't remember the name of the warranty company off the top of my head, I do know it's not GMPP though. I'll post the name of the warranty company and the plan I ordered when I get home from work this evening to see if anybody has experience with them.

Did GMPP cover the cost of the heads? Or are you saying you had the GMPP warranty when you did your heads? If it's the latter, did you consult GMPP to see if that voided the rest of your warranty with regards to the engine?

Sorry for all the questions.

MTPZ06

AHP is an authorized GMPP repair facility, so while I was still under that warranty, I had them do an inspection. My car failed...14/16 guides beyond GM service limits w/15K miles; so they contacted GMPP who sent out a field adjuster to have a look, and validated the claim after their inspection. GMPP paid for the majority of the work I had AHP do, as I chose to "upgrade" some of the valvetrain components with respect to the heads, and paid out of pocket on the difference.

Tha shu

So I just looked into my warranty, and it is Vehicle One which is covered by Ally. I have the Premium coverage (the highest possible coverage).

If anybody has any experience with them, I would be very interested in hearing your experiences with them regarding paying claims.

Thanks!

MacofTampa

I was in the same position as the original poster. New to the GM brand and purchased a 08 Z06 this summer from a long time friend. Car had been babied during my friends ownership and I had no reason to think that there was anything to be concerned about. Within just a couple of tanks of gas through the car I noticed what I felt was excessive valve train noise from a hydraulic roller cam shaft arrangement. Sounded more like a solid roller to me.

As I was new to GM products I had never heard of the valve guide wear issue on LS7s until I simply did a google search (valve train noise LS7). Based on what I read I decided to do my own inspection (pulled passenger side head and disassembled valves) and was very surprised at how much play was in the valve guides at 23K miles on a "babied" engine.

Each owner has to make his own decision, for me if I hadn't checked I probably would have repaired the heads anyway based on what I felt was excessive valve train noise and all the documented low mileage valve guide wear. Also playing into this was the desire to add performance with a cam upgrade. After checking its was a no brainer for me to repair.


Thanks Mike

RamAir972003

No its just frustrating I have been attacked on here before by a vendor on here and the admin protected them,also been by members it really doesn't bother me ik just here to help everyone with results I give results on this forum im not the fastest nor the smartest but when people tell me or ask me about the head issue I don't mind spending 2k to swap out and see just like I am doing on this set. See it doesn't bother me as much of these heads that I pull are out of spec i will try step 3 moldstar guide...i think I will be the only one in history doing this three times with an ls7 casting not aftermarket to find out about this culprit with our heads. If you want to chat pm me i will gladly call you and explain.....Merry Christmas good luck....im out

MTPZ06

To my recollection it's a decent warranty...Ally is GMPP now as well. I think forum member Dirty Howie had a motor replaced under Vehicle One if I'm not mistaken.

American Heritage

One of the best aftermarket warranty company's to work with. We have replaced heads, lifters, shocks, starters, etc.. all under ally/Vehicle One.
You have a very good aftermarket warranty.

http://www.americanheritageperformance.com/

Texan79423

I just love how you guys will argue with a door ****. For one I do believe there is (could) be a problem with the heads. So, why chance it.

Back in the 70's I drag raced a altered car with a dart block and heads on alcohol dropped a valve just before finish line and went end over end through the traps at 162 MPH. Put a window in the block, ruined both heads, and totaled out the car. Only thing saved was the rear end and slicks.

Been there done that and learned from it.

sjhanc

Delivering new engines with excessive valve stem-to-guide clearance is not a NEW thing for GM, they built small blocks on worn out machinery from the late 50's and I found new engines with excessive clearance into the 90's. When the machinery wore out, they sent the stuff to Mexico, then continued to install the Mexican built engines in new cars. the issue that affects valve head durability is called 'walking on their seats'.

The cam-lifter-pushrod-rocker arm-to-valve movement causes a valve with excessive guide clearance to move around inside its valve guide (causing valve seat leakage, and rough engine off idle). When a valve head picks up combustion heat, it transfers this heat to the seat , AND the guide for delivery to the cooling system. If the valve head is not in contact with its seat and guide it can't get rid of the combustion heat, it overheats, turns red, and other brighter colors, then fails and drops off. End of engine! Engines may spark knock, or detonate even on super premium or racing fuel just before the catastrophic failure. The failure may even be blamed on the detonation when the cause is actually loose valve guides.

Most racers know about this, and they don't risk expensive engines on loose guide clearances. Having a machine shop do a relatively inexpensive (compared to engine replacement) preventive maintenance procedure is common sense.

I used to find loose guides in many other types and brands of engines, I just fixed them as part of the work I was already doing. If a customer or service manager questioned my advice I would tell them I would NOT warrantee my work on their engine, I would list the refused, but necessary repair in the work order along with a disclaimer for my responsibility for ANY engine failure they might have. And I would tell the service clerk to make sure they read and signed the note, and also signed the work order.

I once had to fix several new Chevy pickups sold to the University of Florida that had this problem. Once I proved that my fix solved their drivability problem the rest of the fleet was distributed among the other techs in the shop, including the guys who had tuned these engines, overhauled their fuel systems, and tried everything they knew how to do, short of pulling a valve cover to check the guide clearance.

All you have to do to verify valve guide clearance is correct is connect a vacuum guage to a manifold vacuum port and drive it slowly from zero to 10 mph. Bad clearance shows up as rough running just off idle, the guage will fluctuate from 4 up to as much as 13 inches of vacuum WHILE the engine is running rough. Normal manifold vacuum is typically 21-26 inches at idle, dropping to a SMOOTH 12-14 inches under moderate acceleration. At fast idle and above the valve gas leakage becomes only a small percentage of total fuel/exhaust gas flow, so is not noticed during normal driving at speeds above the rough running rpm.

Automatics have a torque converter that partially absorbs the rough running, manual transmission have a clutch that does NOT. Manual cars frequently are diagnosed as having a chattering clutch, but replacing the clutch will NOT fix the rough running. A vacuum guage test will find even ONE loose guide, but usually when a new engine is the subject, most of the guides are sloppy. They didn't wear out, they were built that way, so it IS a pre-existing condition that MUST be covered under original warrantee. The valve gear is part of the Federally certified emission control system, as such is covered for a longer time than the powertrain warrantee. I repaired engines with high mileage (under 100,000 miles and 5 years) under the emissions warrantee.

You guys can afford to buy a very nice car with a dynamite engine, don't bitch about it, fix it right!

The other problem I read about is valve/spring failure not related to the guides. I watch videos of guys who post their track sessions showing the headup display readings to prove that they went so fast. In most of these videos I see them incorrectly shifting gears, they push the clutch in BEFORE they lift the gas pedal. The tach readings are typically late displaying actual rpm changes. This means that when I see a shift and the tach exceeds the redline before the shift is completed, that engine has had its valve gear damaged. Each time the redline is exceeded, even for a split second, some fatigue is added to the valve gear.

It may go on driving ok for a while, then detonate the engine weeks later. The engine is blamed for being a bad design, when actually, the driver did it to himself. 427 engines in particular are more likely, (because of the engine's willingness to rev), to destroy themselves when a valve or spring that has been over-revved several times suddenly lets go. When I raced, I used rev limiters. My driver always said he didn't exceed the redline, but the high needle told me, plus the sound an engine makes when it hits the rev limiter (A dead givaway). I got in the car with him in the passenger seat, floored the gas pedal quickly, then let it up when the rev limiter cut in. He saw that the tach was WAY behind the engine when not in gear. Some of these guys need some training in how to shift their toys correctly. I used to race a 67 C3 with a big block. That engine could be over-revved while driving in 4th gear just by pushing the gas pedal quickly! (we didn't have the tires you guys take for granted). I knew it was too powerful and detuned it to below 600hp. The driver didn't like that but he stopped tearing up drive train parts.