[Z06] Valves covers came off in the name of science
08-19-2012, 11:35 PM
#1
Instructor
Thread Starter
Valves covers came off in the name of science
First off I would like to say that I would like this post to stay on track without the personal banter that has been going on in the other posts. With that said....
My friend bought a 2006 ZO6 about 4 months ago, before he bought he had ran the vin and found out that it had "engine work". In talking to the owner the car had been to the dealer and that they had worked on it and said the repair bill was around 10k and that was all he really knew. The price was right and my friend brought the car home.
He and I have been talking about the dropped valve issue and came to the conclusion that his car was probably a perfect candidate for it. We figured that when it was worked on the most they had done was replace the short block and the heads went untouched so today the valve covers came off.
The first thing I noticed was how clean they were, car has 53,000 miles on it. Second thing I noticed was that all the bolts had the orange paint on them and it matched the other bolts on the heads so we assumed the heads are original. There were no unusual wipe patters anywhere that we could find. What was disturbing to us was how much slop was in the rockers. They will move a good distance back and forth as well as up and down as seen in this video. http://www.youtube.com/watch?v=fx67VSzmhj0 Here is another short clip of one of the others, I can't imagine that this amount of movement is with in tolerances? http://youtu.be/m4ecDMiG2xY I can't imagine that this "play" couldn't contribute to the noisy valve train, you can even hear the one clicking while we're moving it.
Next we had to see if we could get the valves to wobble in the guides. Now they all wobbled both exhaust and intake so I'm not sure if this amount of wobbling is acceptable or not, but needless to say this was just the start unless someone says that this is all normal. http://youtu.be/RaaQsIZ8GI0 http://youtu.be/BLa9sGNXlQE
What says the forum on the subject in the videos?
My friend bought a 2006 ZO6 about 4 months ago, before he bought he had ran the vin and found out that it had "engine work". In talking to the owner the car had been to the dealer and that they had worked on it and said the repair bill was around 10k and that was all he really knew. The price was right and my friend brought the car home.
He and I have been talking about the dropped valve issue and came to the conclusion that his car was probably a perfect candidate for it. We figured that when it was worked on the most they had done was replace the short block and the heads went untouched so today the valve covers came off.
The first thing I noticed was how clean they were, car has 53,000 miles on it. Second thing I noticed was that all the bolts had the orange paint on them and it matched the other bolts on the heads so we assumed the heads are original. There were no unusual wipe patters anywhere that we could find. What was disturbing to us was how much slop was in the rockers. They will move a good distance back and forth as well as up and down as seen in this video. http://www.youtube.com/watch?v=fx67VSzmhj0 Here is another short clip of one of the others, I can't imagine that this amount of movement is with in tolerances? http://youtu.be/m4ecDMiG2xY I can't imagine that this "play" couldn't contribute to the noisy valve train, you can even hear the one clicking while we're moving it.
Next we had to see if we could get the valves to wobble in the guides. Now they all wobbled both exhaust and intake so I'm not sure if this amount of wobbling is acceptable or not, but needless to say this was just the start unless someone says that this is all normal. http://youtu.be/RaaQsIZ8GI0 http://youtu.be/BLa9sGNXlQE
What says the forum on the subject in the videos?
Last edited by Surviving 67; 08-19-2012 at 11:38 PM.
08-20-2012, 02:34 AM
#5
Racer
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That's too loose in my opinion. Try the intake side and you can tell the difference. If I have to guess, you have 8 to 10 thous movement there in the first video, about twice the allowable limit. If the intake side feels like it has half the movement, you have a problem on the exhaust side for sure.
08-20-2012, 08:37 AM
#6
Team Owner
If you can move them side to side at all there is too much play.
08-20-2012, 08:52 AM
#7
Safety Car
That's too loose in my opinion. Try the intake side and you can tell the difference. If I have to guess, you have 8 to 10 thous movement there in the first video, about twice the allowable limit. If the intake side feels like it has half the movement, you have a problem on the exhaust side for sure.
It seems this is the consensus: any movement "by hand" is likely indicative of significant guide wear, although this is not a conclusive test it's highly probable (the only way you'll really know is by pulling the heads and having someone measure with the appropriate micrometers).
IF you buddy decides to pull the heads and have them worked on (which I personally would highly recommend after watching your videos) - please have him post the guide/valve wear measurements for the valve you show in your video so we all can see.
It would be nice to have a way to guesstimate the perceived wobble to actual wear.
08-20-2012, 09:21 AM
#9
I'd find out how long ago the work was done, and more specifically, what exactly did the dealer do. It shouldn't be a big secret. I'd show tech that did the work the video, and get his opinion of the side thrust play on the rockers. I'd be very curious to hear what they say, and to know exactly what work was done.
08-20-2012, 09:40 AM
#10
Drifting
First off I would like to say that I would like this post to stay on track without the personal banter that has been going on in the other posts. With that said....
My friend bought a 2006 ZO6 about 4 months ago, before he bought he had ran the vin and found out that it had "engine work". In talking to the owner the car had been to the dealer and that they had worked on it and said the repair bill was around 10k and that was all he really knew. The price was right and my friend brought the car home.
He and I have been talking about the dropped valve issue and came to the conclusion that his car was probably a perfect candidate for it. We figured that when it was worked on the most they had done was replace the short block and the heads went untouched so today the valve covers came off.
The first thing I noticed was how clean they were, car has 53,000 miles on it. Second thing I noticed was that all the bolts had the orange paint on them and it matched the other bolts on the heads so we assumed the heads are original. There were no unusual wipe patters anywhere that we could find. What was disturbing to us was how much slop was in the rockers. They will move a good distance back and forth as well as up and down as seen in this video. http://www.youtube.com/watch?v=fx67VSzmhj0 Here is another short clip of one of the others, I can't imagine that this amount of movement is with in tolerances? http://youtu.be/m4ecDMiG2xY I can't imagine that this "play" couldn't contribute to the noisy valve train, you can even hear the one clicking while we're moving it.
Next we had to see if we could get the valves to wobble in the guides. Now they all wobbled both exhaust and intake so I'm not sure if this amount of wobbling is acceptable or not, but needless to say this was just the start unless someone says that this is all normal. http://youtu.be/RaaQsIZ8GI0 http://youtu.be/BLa9sGNXlQE
What says the forum on the subject in the videos?
My friend bought a 2006 ZO6 about 4 months ago, before he bought he had ran the vin and found out that it had "engine work". In talking to the owner the car had been to the dealer and that they had worked on it and said the repair bill was around 10k and that was all he really knew. The price was right and my friend brought the car home.
He and I have been talking about the dropped valve issue and came to the conclusion that his car was probably a perfect candidate for it. We figured that when it was worked on the most they had done was replace the short block and the heads went untouched so today the valve covers came off.
The first thing I noticed was how clean they were, car has 53,000 miles on it. Second thing I noticed was that all the bolts had the orange paint on them and it matched the other bolts on the heads so we assumed the heads are original. There were no unusual wipe patters anywhere that we could find. What was disturbing to us was how much slop was in the rockers. They will move a good distance back and forth as well as up and down as seen in this video. http://www.youtube.com/watch?v=fx67VSzmhj0 Here is another short clip of one of the others, I can't imagine that this amount of movement is with in tolerances? http://youtu.be/m4ecDMiG2xY I can't imagine that this "play" couldn't contribute to the noisy valve train, you can even hear the one clicking while we're moving it.
Next we had to see if we could get the valves to wobble in the guides. Now they all wobbled both exhaust and intake so I'm not sure if this amount of wobbling is acceptable or not, but needless to say this was just the start unless someone says that this is all normal. http://youtu.be/RaaQsIZ8GI0 http://youtu.be/BLa9sGNXlQE
What says the forum on the subject in the videos?
On the rockers mine were the same way and that was the reason that I also did the CHE Rocker upgrade when I sent my heads and rockers to WCCH for repair....
Mark
08-20-2012, 10:16 AM
#12
Race Director
08-20-2012, 11:07 AM
#13
Instructor
Thread Starter
I'd find out how long ago the work was done, and more specifically, what exactly did the dealer do. It shouldn't be a big secret. I'd show tech that did the work the video, and get his opinion of the side thrust play on the rockers. I'd be very curious to hear what they say, and to know exactly what work was done.
He had a set of LS1 heads in his garage with 25,000 miles on them and we couldn't get the valves to wobble on them. What about the rockers is this normal or are they shot?
Bill
08-20-2012, 08:30 PM
#14
Yes, call the dealer and find out what was done. There is a service history for the vehicle, and it's not a secret. They should readily share it with your friend as the owner of the vehicle.
08-20-2012, 08:58 PM
#15
Le Mans Master
The OEM rocker arms in my LS6 (same basic design as the LS7 rockers) had a lot of side-to-side play too ... around 0.020~0.025". But the video of the rocker arm out of the engine with the radial slop seems way too much to me. I put the Comp Cam trunnion kit in my LS6, and there was zero radial play in those bearings.
08-20-2012, 09:35 PM
#16
The OEM rocker arms in my LS6 (same basic design as the LS7 rockers) had a lot of side-to-side play too ... around 0.020~0.025". But the video of the rocker arm out of the engine with the radial slop seems way too much to me. I put the Comp Cam trunnion kit in my LS6, and there was zero radial play in those bearings.
08-20-2012, 09:46 PM
#17
Burning Brakes
Member Since: Jul 2002
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When the hysteria started weeks ago, I pulled the passenger side cover (very fast and easy to do) and did the 'wiggle' tech with my fingers. Yes, the intake and exhaust wiggled. I took video of it and didn't post it here because I then went to a SBC head I had for my 383 (SBC Dart Head) and I could force a 'wiggle' too with the spring on. I wanted to check some other heads because getting folks worked up.
My rockers also do the side to side but I didn't pull them to check play. I have a set of old LS1 rockers laying around with 85k on them so I'll check those also. The most frustrating part about all this is the lack of response from the professional engine builders to set the record straight if this type of 'wiggle' is a cause for alarm, etc. I know they run a business to make a profit, but solely only selling stuff on the forum without helping tends to make me remember and look elsewhere for a vendor. So when I see companies step up, I take note of who will earn my future business.
Honestly, I will take corrective action (pull heads & do it Katech way likely) but I'm not going to be parnoid about it and not enjoy the car until then.
I would imagine that GM has to be doing the math and if indeed there is an extremely high failure rate and they ignore it, then eventually folks will get together with a class action suit perhaps.
My rockers also do the side to side but I didn't pull them to check play. I have a set of old LS1 rockers laying around with 85k on them so I'll check those also. The most frustrating part about all this is the lack of response from the professional engine builders to set the record straight if this type of 'wiggle' is a cause for alarm, etc. I know they run a business to make a profit, but solely only selling stuff on the forum without helping tends to make me remember and look elsewhere for a vendor. So when I see companies step up, I take note of who will earn my future business.
Honestly, I will take corrective action (pull heads & do it Katech way likely) but I'm not going to be parnoid about it and not enjoy the car until then.
I would imagine that GM has to be doing the math and if indeed there is an extremely high failure rate and they ignore it, then eventually folks will get together with a class action suit perhaps.
08-20-2012, 09:57 PM
#18
Melting Slicks
The slop you see in the rockers is normal for these LS7s.
Prove it to youself by buying a new one from your dealer and you will see yours are "like new"..............
Prove it to youself by buying a new one from your dealer and you will see yours are "like new"..............
08-20-2012, 10:38 PM
#19
Race Director
The most frustrating part about all this is the lack of response from the professional engine builders to set the record straight if this type of 'wiggle' is a cause for alarm, etc. I know they run a business to make a profit, but solely only selling stuff on the forum without helping tends to make me remember and look elsewhere for a vendor. So when I see companies step up, I take note of who will earn my future business.
