[Z06] What does the vavle guide issue sound like?
#1
What does the vavle guide issue sound like?
I just bought a '09 Z06. Absolutely love it so far, much faster/better than my old 2005 z51.
Anyway I had the heads checked before I bought it and all the measurements for the exhaust valves were well within spec so I didn't do anything with the heads. First question is: should the shop have checked intake valves too? I thought that the problem affected both intake and exhaust valves but maybe not.
Second question is what should I look out for? How will I know if the heads are about to go? I have heard from some other posters here that before the heads went there was a sound that came from the engine bay/valve train. What does this sound sound like?
Anyway I had the heads checked before I bought it and all the measurements for the exhaust valves were well within spec so I didn't do anything with the heads. First question is: should the shop have checked intake valves too? I thought that the problem affected both intake and exhaust valves but maybe not.
Second question is what should I look out for? How will I know if the heads are about to go? I have heard from some other posters here that before the heads went there was a sound that came from the engine bay/valve train. What does this sound sound like?
#2
Racer
Intake/Exhaust valve guides wear out. My intakes were worse than the exhaust, every cars different. As far as sound just loud ticking more than usual but unfortunately a valve can drop with no warning or funky sounds. Best to get the guides replaced and a 1 piece exhaust valve put in. AHP did mine Kohle and his crew were awesome to work with, highly recommend them.
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vader03 (10-25-2016)
#3
Team Owner
Both sides should be inspected, as failure can occur on either side. There seems to be a higher "known" failure rate on the exhaust side, most likely due to the thin wall hollow stem OE exhaust valve...but both sides can wear excessively and cause catastrophic failure.
As for a telltale sound...there isn't one. The first and last sound you hear is your engine ingesting a valve head, and most likely kicking chunks out through a brand new window in your block.
As for a telltale sound...there isn't one. The first and last sound you hear is your engine ingesting a valve head, and most likely kicking chunks out through a brand new window in your block.
Last edited by MTPZ06; 10-24-2016 at 11:38 PM.
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Landru (10-25-2016)
#5
Race Director
Yes, both sides need to be checked. At 46K miles on my 09Z, I did HCIE because I wanted to check the valve guides. All exhaust guides and 6 of 8 intake guides were out of spec, some more than 2X the .0037 limit, all were worn hourglass shape with intakes wider at the top and exhust wider at the bottom..
#6
Supporting Vendor
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When the LS7 valve guides fall out of spec you have a more audible valve train noise in the 1,500-2,000 rpm range.
The sound that you are listening for is a "metallic" type sound, its a hard sound to describe but the best words would be "metallic".
The Sound gets more pronounced the larger the valves guide clearances get. A shop that does alot of LS7's could hear the sound we are describing but most would more than likely not and pass the sound off as normal.
The LS7 and LS engines by design a very noisy platforms but the common LS sounds are either crickety (injectors), clacky and or tappy (lifters/rockers) not metallic like what out of spec valve guides sound like.
Once your ears are trained/adjusted for the sound it become pretty easy to hear. We do alot of C6z06 work (we keep between 10-20 c6z06's at our shop at any given time and have done so for years) we have noticed that the Titanium intake valves make a very strange sound when they fall out of spec vs when the sodium filled SS exhaust valves fall out of spec.
If you would like to speak with us on the phone you can always give us a call
310-326-2399
We are glad to answer any questions you might have.
Also Yes as mentioned above when checking valve guides you typically want to do both the intakes and the exhausts
http://www.americanheritageperformance.com/
The sound that you are listening for is a "metallic" type sound, its a hard sound to describe but the best words would be "metallic".
The Sound gets more pronounced the larger the valves guide clearances get. A shop that does alot of LS7's could hear the sound we are describing but most would more than likely not and pass the sound off as normal.
The LS7 and LS engines by design a very noisy platforms but the common LS sounds are either crickety (injectors), clacky and or tappy (lifters/rockers) not metallic like what out of spec valve guides sound like.
Once your ears are trained/adjusted for the sound it become pretty easy to hear. We do alot of C6z06 work (we keep between 10-20 c6z06's at our shop at any given time and have done so for years) we have noticed that the Titanium intake valves make a very strange sound when they fall out of spec vs when the sodium filled SS exhaust valves fall out of spec.
If you would like to speak with us on the phone you can always give us a call
310-326-2399
We are glad to answer any questions you might have.
Also Yes as mentioned above when checking valve guides you typically want to do both the intakes and the exhausts
http://www.americanheritageperformance.com/
#8
Le Mans Master
On my 2011, the exhausts were all fine, but several intakes were out.
Keep in mind this has everything to do with the accuracy of the initial machining from the 3rd part vendor when the heads were built.
The observed pattern - earlier cars 2006 - 2009 tend to have exhaust guides out of spec, later cars 2009 - 2013 tend to have intakes that are out.
It's the luck of the draw really, so yes, all of them should have been checked.
The "good" part of this story is intakes rarely (if ever) drop from the abuse of excessive guide clearances - that doesn't mean you should ignore the issue, it just means it's far less likely you'll have a ventilated block the next time you start it.
Keep in mind this has everything to do with the accuracy of the initial machining from the 3rd part vendor when the heads were built.
The observed pattern - earlier cars 2006 - 2009 tend to have exhaust guides out of spec, later cars 2009 - 2013 tend to have intakes that are out.
It's the luck of the draw really, so yes, all of them should have been checked.
The "good" part of this story is intakes rarely (if ever) drop from the abuse of excessive guide clearances - that doesn't mean you should ignore the issue, it just means it's far less likely you'll have a ventilated block the next time you start it.
Last edited by Dan_the_C5_Man; 10-25-2016 at 02:22 PM.
#9
Melting Slicks
#10
Team Owner
My early build '09 must have been right in the middle of whatever adjustments they were making to the machines there at Linamar, because at 15,000 street miles all of my intake and exhaust guides were beyond service limits except for Cyl #2 where both guides were right at the limits.
#11
Le Mans Master
My early build '09 must have been right in the middle of whatever adjustments they were making to the machines there at Linamar, because at 15,000 street miles all of my intake and exhaust guides were beyond service limits except for Cyl #2 where both guides were right at the limits.
You'd think running a mutli-million dollar operation, they could manage to drill a hole to the right size and on-center..
#12
Race Director
Yeah, you had a set where they f'ed both sides - maybe they felt the exhausts were getting too much "attention", they wanted the intakes to "feel the love" as well.
You'd think running a mutli-million dollar operation, they could manage to drill a hole to the right size and on-center..
You'd think running a mutli-million dollar operation, they could manage to drill a hole to the right size and on-center..
#13
Team Owner
Yeah, you had a set where they f'ed both sides - maybe they felt the exhausts were getting too much "attention", they wanted the intakes to "feel the love" as well.
You'd think running a mutli-million dollar operation, they could manage to drill a hole to the right size and on-center..
You'd think running a mutli-million dollar operation, they could manage to drill a hole to the right size and on-center..
Agreed. Probably a budgetary decision...lowest bidder syndrome comes to mind.