erick_e

So I am in possession of John_G famous tool to measure geometry.

I've been traveling back and forth between TN and NC before I go on extended travel outside the Country.

First I pulled the spark plugs and most of them looked dry. There were two that had some oil on the threads.







Then after removing the rockers I thought things were looking good, as the wear pattern seemed to be rectangular. But, I couldn’t stop there, I had to measure the actual clearance because I want to modify the engine. I bought am Edelbrock E-Force last year, and have been holding off on the install because of these valve issues. Good thing I did.












Since the exhaust valves seen to have the most wear, I removed the #1 exhaust spring, lifted the valve off the seat a little and measured the clearance. .015” Yes that is correct. You can visibly see the movement in the valve. You don't need a dial gauge to tell you that it's shot.



Then I move on to #5, and check the intake. Yep, don't need a dial gauge here either.








#5 exhaust is next



At this point, I really didn’t want to check any more, but thought I would check the other side, so I check cylinder #4

Yep. Its shot too at .010"



And a few pictures of the wear pattern on the valve stems. Looks like a good wipe pattern for the most part.










So with 36238 miles, what do I do?



I'm still in my warranty window of 4/48 for a CPO. But haven’t had any good experience with a dealer doing any major repair. That’s another threat in itself. Do I take the chance of some kid doing a hack job repair at the dealer, or should I just embrace the suck, and sent my heads off for repair, and have the peace of mind that it is done right?

BTW, thanks to John_G. I wouldn’t have started this unless I had the tool to measure my geometry, which measured good, by the way.

'06 Quicksilver Z06

Wait a minute.

Your geometry measured good, but your guides are shot?

erick_e

All of the the rocker pedestals were all within .001" of each other in height.

'06 Quicksilver Z06

Is that "good"?

I haven't been keeping up with the geometry thread.

And if it is good, well then what do you supposed caused the guide wear?

Also, can you cash the warranty out?

If so, then I would, and put the money toward's having the heads done right instead of getting a new set of stock heads, which is probably how they are going to handle this under warranty.

I think you answered your own question, with your "peace of mind that it is done right" portion of your prior post.

Peace of mind, is never free, nor cheap.

RamAir972003

The documentation you have and videos on here should be enough to get you a set of new heads. Im site a gm rep on here can help you....

TARANTULA

Pay the dealer to check your car per the last TSB and they should replace the heads under warranty

Jackal

I would go the safe route, and either buy a set of heads that are worked up properly, or rebuild your stockers.

Dirty Howie

Is your car stock, no tune, no track ??

Those are as bad as what Richard was showing me at WCCH !!

Did you have the cylinder pressurized to keep the valve from falling or piston at TDC? It was hard to tell in your video, how much off the seat did you have the head when wiggling the stem?

Thanks for all the video


DH

erick_e

I guess what it means is that all of the rocker pedestals are all parallel to each other, and not misaligned.

I noticed that the guides seemed to have more wear north to south, than west to east. So, I think they were machined incorrectly. Maybe not parallel with the valve seat?? I can only guess here.

I did buy an extended warranty through Fichtner, so I could cash that out.

Car is completely stock, except for a DeWitts radiator. Never been tracked by me, and only had a handful of pulls above 6K.

I did pressurize the cylinders, but since all the spark plugs were removed the air pressure just pushed the cylinder down to BDC. That is why you see a "wrap" around some of the valves so they wouldn’t fall through.

I tried to just lift the valve off the seat when measuring, which is why you see me pull them up and down in the guides several times.

Jackal

I wish I had done this test before my motor popped. now I have to buy a new engine.

JeffInDFW

Impossible. GM assured us that the valve guide issue is nothing but internet fantasy. The 80% of the owners here who have NOT had a problem have assured us that this is not a problem. But I ask, how many people have posted this week that they broke a timing chain on their LS7? Spun a bearking? Broke a ringland? ANY other kind of failure?

OH, and I notice the exhaust valves have the most ware. No mods.

ATC399

4/48 CPO are you the original owner?

john_g_46

Eric,

You don't have the numbers to know if your geometry is good or bad. You have consistent measurements but they may be consistently bad. I need you to send the numbers to me. I have an Excel spread sheet with good and bad measurements.

I see brown crescents and round edges on the wear marks on the rockers. Both are indicative of bad geometry. As oily as two of those plugs are, the seals of those cylinders are shot as well.

John

C6z06man

Wow those are pretty bad. I'm glad you caught it before something catastrophic happened. Good luck on the repair.

z51vett

Call Jim Ellis chevrolet in Atlanta Ga. ask to speak to David Fulcher the Corvette Tech. He maybe able to help with what the next step should be. If you can get it to David he is the best tech I've ever seen.
z51vett
Jim Ellis 770-457-8211

LeftLane Z06

If they are willing to work with you....
I would buy a set of PRC's or Brodix heads and see if the dealer would install them instead of the OEM heads and sell then sell new OEM warranty heads.

If not, warranty the oem heads and pay to have after market heads installed there at the dealer.

JwT

Well first of all you were smart on not buying the (It's not a problem) that GM thinks they can get away with. A lot of folks are sticking their heads in the sand about this. You do have options, but I think getting a new set of GM heads will only postpone the problem for another 30k miles or less. Quicksilver said it best, it's going to cost money for piece of mind. I'm doing the Texas Speed PCR's as we speak. But I could have sent my heads to them for about $1400.00.

WhiteDiamond

I have almost the same wear patterns on most of my rockers. I had a dripping wet plug come out of cylinder 4's exhaust and 2 and 6 had more oil on them than the plugs shown in this thread. I only checked my #4 exhaust valve and it looks like your vid above. I figured with noticeable movement in the stem, I didn't need to go any farther.

jedblanks

This is just sad. It's so obvious that GM is lying and in the same breath belittling owners.

I own two corvettes and I've owned many GM cars in the past. I guess I've always ignored the problems because I liked the cars. I'm DONE if GM doesn't come clean, explain why this is happening and FIX IT for ALL LS7s.

I only wish that this issue was more simple so that I could explain it better to all of the people I'm going to tell.

Maybe "I bought a 65,000 car that had a 17,000 engine that I was afraid would kill me at 15k miles due to a product flaw that GM refused to admit." Will work.

Fool me once....

erick_e

I'm in the process of uploading the geometry measurements, and going to send them to John_G for definitive confirmation of geometry.