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Old 02-10-2014, 03:32 PM   #1
mkorgan
 
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LS7 Proactive Valve Remedy

Let me state up front that I am not an expert on the LS7 or the valve train issue that is covered in detail on the corvette forums. I do see that it is still an issue so I ask the following question: What are the options (short of replacing the heads) to proactively address the valve issue before it becomes a problem and dumps the top side of the motor? I will be getting a new Z/28 and will probably address this right up front so that I don't end up on the back of flatbed coming home from the track.
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Old 02-10-2014, 05:47 PM   #2
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Ask GM. They know best, they make the engine and warranty it. I have one coming also, but I am not going to worry about a rumored problem that others have on a older car.
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Old 02-10-2014, 06:40 PM   #3
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Did not say I was worried, I just am interested I what can be done to avoid as it is not a rumor and is a known issue on LS7 shipping as recently as 10 months ago. My understanding is that the LS7 in the Z/28 is the same LS7 built for the Corvette under the same design so I think it is a valid question. If you choose to dismiss or ignore it then that's cool for you but I am looking for someone in the business who can provide sound technical guidance.
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Old 02-10-2014, 06:45 PM   #4
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It's a rumor as far as the LS7 on the Camaro, they are not built yet.
That's why I say to ask GM, they know the issue. Where did I say you were worried? I said I would not.
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Old 02-10-2014, 07:00 PM   #5
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Awesome. I appreciate the fact this issue does not worry you. My brother-in-law has a LS7 in his vette and the dealer told him that there is nothing that they recommend to avoid the issue other than try to avoid high RPM ranges for extended periods of time. They acknowledged it is a known issue with a service bulletin associated with it but they do not do anything to proactively correct the problem as it effects less than 5% of the LS7 produced based on reported incidents. He laughed and said they recommended getting the extended warranty. Nice.
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Old 02-10-2014, 07:11 PM   #6
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They would be like aircraft engines, if the are going to come apart it is going to be the first 100 hours and in the cars case 10k miles.
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Old 02-10-2014, 07:15 PM   #7
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Awesome. I appreciate the fact this issue does not worry you. My brother-in-law has a LS7 in his vette and the dealer told him that there is nothing that they recommend to avoid the issue other than try to avoid high RPM ranges for extended periods of time. They acknowledged it is a known issue with a service bulletin associated with it but they do not do anything to proactively correct the problem as it effects less than 5% of the LS7 produced based on reported incidents. He laughed and said they recommended getting the extended warranty. Nice.
Just to play devil's advocate - so you think that, of the less than 5%, just by chance this could happen to you, you want to eliminate that possibility completely by finding a resolution to the issue?
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Old 02-10-2014, 07:18 PM   #8
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95% that it will not happen! I like those odds.
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Old 02-10-2014, 07:53 PM   #9
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these forums are so helpful at times...and then there are times like this.

If you don't have anything to recommend (other than don't worry about it or ask GM) then that's cool...feel free to not post.

If no one else post then I will accept the fact that I am the only one thinking about it.
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Old 02-10-2014, 08:27 PM   #10
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Did not say I was worried, I just am interested I what can be done to avoid as it is not a rumor and is a known issue on LS7 shipping as recently as 10 months ago. My understanding is that the LS7 in the Z/28 is the same LS7 built for the Corvette under the same design so I think it is a valid question. If you choose to dismiss or ignore it then that's cool for you but I am looking for someone in the business who can provide sound technical guidance.
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these forums are so helpful at times...and then there are times like this.

If you don't have anything to recommend (other than don't worry about it or ask GM) then that's cool...feel free to not post.

If no one else post then I will accept the fact that I am the only one thinking about it.
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CAFE STANDARDS! Get used to them or vote our electeds in Washington out of office...........
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Old 02-10-2014, 08:39 PM   #11
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Dear Skylane,
Please stop posting such blatent misinformation. The original posters question is valid and would be a concern of mine if I were to have a stock ls7 head.
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Old 02-10-2014, 08:47 PM   #12
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Dear Skylane,
Please stop posting such blatent misinformation. The original posters question is valid and would be a concern of mine if I were to have a stock ls7 head.
I posted for him to ask GM, nothing wrong with that post, I also never told him not to worry, I said I would not worry about it. Who are you to say what I can post. Nothing wrong with my post. I also have a Z28 coming, so I stated what I would do.
What misinformation?
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Old 02-10-2014, 09:03 PM   #13
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http://www.camaro5.com/forums/showth...52#post7409352

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Old 02-10-2014, 09:04 PM   #14
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From my understanding it is a hollow valve/ bad geometry problem putting a side load on the stem.

I pulled the covers on my Z06 and the rockers all made proper contact. granted I only put 26k on the car I had but they were spirited miles.

So people will make coments like trust the waranty and all that but I dont' like down time on my car so I just inspected the parts proactivly.

now this is what I gleaned out of the hours of reading I did when I had mine. If it turns out to be bad parts on the other had the fix would simply be different valves.

all you have to do is read for 5min on this topic and you will see there is no agreement on the issue. Some will put 60k on the stock motor. some will fail early. that is why I inspected the valve train to remove that varible. If mine had failed I would have know it was most liklely a bad spring or valve not a missalignment multiplied by high RPM issue.
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Old 02-11-2014, 06:03 AM   #15
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The issue is specifically with the titanium intake valves. I saw an 06 that had been rocking a cam for a while (and not a good spec'd cam) and he pulled the heads to get them ported and get a good spec'd cam for his motor. The intake valves had so much play in the head it was ridic. But yes they call it valve stem guide wear and I'm not sure in GM engineers know what's causing this issue, or if they're even admitting it's an issue. I do know that this issue has arisen in the past couple of years and the LS7 has been out since about Feb of '06. Like all issues it won't affect every car. Like hognutz said, you can pull the rocker cover and see if they're making proper contact.

I do know that if you're thinking about modding a Z/28, you can be willing to bet GM won't be as mod friendly on the service side. Those LS7s are expensive and motor claims will probably trigger a field engineer to inspect.
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Old 02-11-2014, 07:09 AM   #16
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is there a noise the comes on and let's you know the problem happening before failure? I am monitoring the S/C coupler noise in my ZL1 which is very minimal at this point but is there something similar you can listen for in the LS7 valve train, like a lose rocker?
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Old 02-11-2014, 09:36 AM   #17
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If you want to be proactive.... Use great oil. Something like an Amsoil. And be careful with the break in.

A lot of valve to valve guide wear occurs during break in. Especially if that clearance is a hair on the tight side when green new. The seals are new, the parts are tight... there won't be much oil lube in there, and lots of heat. Recipe for galling if pushed hard when green.

So many people talk about driving brand new engines like they stole them. Trouble is, if there is a valve stem a bit snug it will gall like crazy.. and that starts the premature wear. Break it in easy and let the valve stems and guides get to know each other gives it a much better chance at maintaining proper clearances. Not super easy, just normal driving, moderate varying loads.

Info is from a neighbor who works in powertrain dyno testing for one of the big three. Tells me all the time about what happens when a green engine is thrashed wide open. Most survive... but if one has a tight valve or a tight piston... bad things happen. That same engine with parts a hair too tight, if broken in easy will be just fine.
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Old 02-11-2014, 10:31 AM   #18
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If you want to be proactive.... Use great oil. Something like an Amsoil. And be careful with the break in.

A lot of valve to valve guide wear occurs during break in. Especially if that clearance is a hair on the tight side when green new. The seals are new, the parts are tight... there won't be much oil lube in there, and lots of heat. Recipe for galling if pushed hard when green.

So many people talk about driving brand new engines like they stole them. Trouble is, if there is a valve stem a bit snug it will gall like crazy.. and that starts the premature wear. Break it in easy and let the valve stems and guides get to know each other gives it a much better chance at maintaining proper clearances. Not super easy, just normal driving, moderate varying loads.

Info is from a neighbor who works in powertrain dyno testing for one of the big three. Tells me all the time about what happens when a green engine is thrashed wide open. Most survive... but if one has a tight valve or a tight piston... bad things happen. That same engine with parts a hair too tight, if broken in easy will be just fine.
Thanks for great insights. Some more info here:

http://en.wikipedia.org/wiki/Galling
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Old 02-11-2014, 05:56 PM   #19
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...So many people talk about driving brand new engines like they stole them. Trouble is, if there is a valve stem a bit snug it will gall like crazy.. and that starts the premature wear. Break it in easy and let the valve stems and guides get to know each other gives it a much better chance at maintaining proper clearances. Not super easy, just normal driving, moderate varying loads...
I've never understood guys who believe that breaking in a car hard and fast results in a faster car. Engineers aren't stupid, and engines need time for all the parts to bed in and settle down. Though it will be painful, I'm willing to baby my Z/28 and break it in softly and slowly -- and then I'll track the hell out of it...
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Old 02-11-2014, 06:21 PM   #20
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is there a noise the comes on and let's you know the problem happening before failure? I am monitoring the S/C coupler noise in my ZL1 which is very minimal at this point but is there something similar you can listen for in the LS7 valve train, like a lose rocker?

Valve train noise is one way; but there is a specific way to measure the valve play (called the wiggle test) as noted in TSB. If you read the other corvette forum; there is a ton of information on this subject. One would think GM has addressed this on the Z/28 because the internal engine components are different and this is really the only knock on an otherwise great motor. With that said, I would not hesitate running the car to redline if I owned either car.
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Old 02-11-2014, 06:47 PM   #21
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Valve train noise is one way; but there is a specific way to measure the valve play (called the wiggle test) as noted in TSB. If you read the other corvette forum; there is a ton of information on this subject. One would think GM has addressed this on the Z/28 because the internal engine components are different and this is really the only knock on an otherwise great motor. With that said, I would not hesitate running the car to redline if I owned either car.
Perhaps one of the unofficial official GM people could throw us a bone and make an unofficial clarification comment here . . . .
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Old 02-11-2014, 07:36 PM   #22
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Perhaps one of the unofficial official GM people could throw us a bone and make an unofficial clarification comment here . . . .
Yes, that's what I recommend. Maybe even a copy of the service bulletin.
That would help.

We do the wiggle test on Lycoming engines because of the valve being too tight.

It is also common for a factory to do a fix but not let it be known because all the prior owners may want that fix and not need it in reality, being only a few were affected. Now if a safety issue, that would have to be addressed on all known cars.
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Old 02-16-2014, 12:26 PM   #23
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Ok guys... I own a LS7 motor. I have it in a 1932 ford pro street truck. The Exhaust valves, And all the valve guides are the problem. I have done, a lot of research, on this problem. The best advice, I can give you, is to do what so many of us LS7 owners have done. Send the heads off to WCCH, That's west coast cylinder heads. Have all new valve guides installed. And remove the sodium exhaust valves. Replace them with stainless exhaust valves. This seams to fix the problem. I have not heard of anyone having any problems, after doing this to the LS7 heads. That includes me.
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Old 02-16-2014, 01:23 PM   #24
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Ok guys... I own a LS7 motor. I have it in a 1932 ford pro street truck. The Exhaust valves, And all the valve guides are the problem. I have done, a lot of research, on this problem. The best advice, I can give you, is to do what so many of us LS7 owners have done. Send the heads off to WCCH, That's west coast cylinder heads. Have all new valve guides installed. And remove the sodium exhaust valves. Replace them with stainless exhaust valves. This seams to fix the problem. I have not heard of anyone having any problems, after doing this to the LS7 heads. That includes me.
And how much does this cost if you don't mind sharing?
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Old 02-16-2014, 01:31 PM   #25
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Quote:
Originally Posted by Russell James View Post
If you want to be proactive.... Use great oil. Something like an Amsoil. And be careful with the break in.

A lot of valve to valve guide wear occurs during break in. Especially if that clearance is a hair on the tight side when green new. The seals are new, the parts are tight... there won't be much oil lube in there, and lots of heat. Recipe for galling if pushed hard when green.

So many people talk about driving brand new engines like they stole them. Trouble is, if there is a valve stem a bit snug it will gall like crazy.. and that starts the premature wear. Break it in easy and let the valve stems and guides get to know each other gives it a much better chance at maintaining proper clearances. Not super easy, just normal driving, moderate varying loads.

Info is from a neighbor who works in powertrain dyno testing for one of the big three. Tells me all the time about what happens when a green engine is thrashed wide open. Most survive... but if one has a tight valve or a tight piston... bad things happen. That same engine with parts a hair too tight, if broken in easy will be just fine.
Great info! I have always followed the break in procedure on other cars. What is it on a new Camaro? 1000 miles varying rpms and never over 5k?
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