Potential valvetrain problem?

Tech discussions on the L77 6.0L V8.
Navy Lifer
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Potential valvetrain problem?

Post by Navy Lifer »

Somewhere in the various posts, between e-mails & threads already begun in New Caprice, I recall a comment or concern about valvetrain issues--but I may be dreaming.

Anyway, it seems there are, potentially, some things to be watching that were issues on the L76 version of the 6.0L. Just passing along, have not dug deeply into any of this info. Something to be aware of and "keep an eye" on.

https://www.google.com/search?q=l76+lif ... annel=fflb
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elc32955
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Re: Potential valvetrain problem?

Post by elc32955 »

Glad you jogged our memory on this one Bill. The problem with the L76's is with the AFM lifters. Seems they like to tick and/or fail. If they fail there's a good chance the cam may go with them it seems. Should be plenty of info on this over on the G8 forums. I was thinking about this very same thing earlier today when I was making the tuner post, Howard from Redline mentioned it during his session last year at his shop in Pompano.

One of the cures he mentioned was programming the AFM "OFF" in the tune, and then removing the lifters first time the engine was open and replacing with standard lifters. I was going to 86 the AFM anyway because of drone in 4cyl mode.

Found the following forum reference discussing some of the problem, this one was from LS1 forums from down under..

http://www.ls1.com.au/forum/archive/ind ... 39850.html

Another thread from one of the G8 forum systems discusses this in depth. There's apparently a service bulletin out on this for the G8's and a few other cars. However, unknown if it applies to us yet with the L77's.

http://forum.grrrr8.net/showthread.php?t=14256

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Re: Potential valvetrain problem?

Post by leadfart »

I had this discussion with my tuner, installer, of my blower. In my situation, AFM is turned off. He said, generally, the AFM lifters would hold up all right, when they were turned off, even with agressive heads and cams. Down the road, he recommended changing them out, at some time.

He didn't think I needed them replaced at this time. And, I'm not spinning the engine up real high, either. It's got plenty on ten pounds of boost.

I hope he's right. :twisted:
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Crazy Paul
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Re: Potential valvetrain problem?

Post by Crazy Paul »

The L77 will have a more recent revision of AFM lifters than the first G8's had in their L76....still the issues will remain. A common theory is that AFM lifters have a much smaller internal oil capacity than normal lifters and are more prone to bleeding down of their internal oil cushion.

The following information was put together for L76 but will still apply to L77.
http://forum.grrrr8.net/showthread.php?t=462
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Re: Potential valvetrain problem?

Post by Pursuit »

Just read the above link from Crazy Paul. He is going to be a great resource!
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Re: Potential valvetrain problem?

Post by nick brown »

how about people who turned off the AFM? do they runinto problems still?
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Navy Lifer
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Re: Potential valvetrain problem?

Post by Navy Lifer »

I'm inclined to say the potential remains higher for problems--the real fix is to replace the AFM lifters with conventional lifters. I won't say it's "that simple", but that's the basic option available to be sure the AFM configuration can't contribute a known failure mode or condition.
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Re: Potential valvetrain problem?

Post by greasychevy »

So, heres what i know. there was a problem with the lifters in the l76. may or may not have been fixed for l77, i doubt it. GM has released a new oil grade called "dexos" it is designed for this problem and the problems they had with the 3.6 timing chains. suposidly it will not airrate as bad... i dunno i use the dexos labeled mobile one in my car. I have my AFM turned off via tune. that is the best way for longevity. since the lifters are never without oil pumping though them there is less potentiol for air and sludge to become a problem. The only real fix is to delete the AFM amd install new lifters and pushrods. You can run a MILD cam with stock lifters and pushrods but why? i wouldnt take that risk anyway. LS7 lifters are they way to go, prolly pushrods too but im not sure. You need to pull the the heads to remove the lifters. So its not a small job. They sell "AFM delete" cam Kits at texas speed or livernois. they come with everything you need for a cam swap. about 1300 bucks. Im saving for that kit and a new set of heads.
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Timmyw04
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Re: Potential valvetrain problem?

Post by Timmyw04 »

Well guys I'm pretty sure we have the same problem as the L76. Got home from work today and heard the dreaded tick. I've always had a tick when first starting for a second or two especially if let set over night but this sounds horrible. I'll be taking it to the dealer in the morning.
Stupid "AFM" !!
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Re: Potential valvetrain problem?

Post by Timmyw04 »

Great they can't check it out till Monday morning
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