[Z06] Don't want to do heads twice...
06-29-2015, 02:22 PM
#1
Safety Car
Thread Starter
Don't want to do heads twice...
Is there a definitive test that can be done to know if my heads were not built properly so I don't have to repeatedly remove them and check for oversized (or misshaped) guide openings?
Guide angle? Guide material? Guide length? Valve wall thickness? etc.
2010 with 9k miles
Guide angle? Guide material? Guide length? Valve wall thickness? etc.
2010 with 9k miles
06-29-2015, 02:42 PM
#2
Le Mans Master
The bottom line here - checking at 10K mile intervals, you will either have so little fore / aft movement it is barely detectable by hand, or they will clearly rock back and forth (and the final validation of this is they will show insignificant movement in the left to right directions).
06-29-2015, 02:45 PM
#3
Safety Car
Thread Starter
Not really, and no, you do NOT need to remove the heads to check to see if your guides are on the road to ruin. If they are really bad, you don't even need to remove the springs, but if you want to do it "right", you just need to remove the spring (and possibly seal, but I wouldn't bother - you can easily overcome the resistance of the seal lip).
The bottom line here - checking at 10K mile intervals, you will either have so little fore / aft movement it is barely detectable by hand, or they will clearly rock back and forth (and the final validation of this is they will show insignificant movement in the left to right directions).
The bottom line here - checking at 10K mile intervals, you will either have so little fore / aft movement it is barely detectable by hand, or they will clearly rock back and forth (and the final validation of this is they will show insignificant movement in the left to right directions).
06-29-2015, 02:59 PM
#4
Le Mans Master
Trust me (and everyone else that has applied logic and common-sense to this issue) - If you use the "wiggle test" appropriately, as a go / no-go gauge, you'll be fine.
06-29-2015, 03:18 PM
#5
Safety Car
Thread Starter
Oh yeah.. And we care about THEIR opinion? Really? The same group that offered zero new information via Tadge, and instead thought it was a great idea to simply move the "out of spec" dimensions forward? Trust me - on this issue, you need to educate yourself and take matters into your own hands - relying on GM to cover you is not a reasonable option (if you care about keeping the original motor in your car anyway - some people with warranties don't).
Trust me (and everyone else that has applied logic and common-sense to this issue) - If you use the "wiggle test" appropriately, as a go / no-go gauge, you'll be fine.
Trust me (and everyone else that has applied logic and common-sense to this issue) - If you use the "wiggle test" appropriately, as a go / no-go gauge, you'll be fine.
I thought I read Katech also stated that the wiggle test was inaccurate. It makes me sick to think that shops have been recommending head replacements for a test that was "inaccurate at best" according to the most recent data. That includes GM dealers.
I do appreciate the input and your willingness to help but there is so much misinformation on this topic that when someone says "trust me" I get an uneasy feeling.
Too many untrustworthy people use that phrase (no offense to you, as I have no reason to distrust you specifically).I was hoping I could remove the head and take measurements of the guides to know if replacing them is my only long term fix for the problem, regardless of the current shape and size of the inside of the guide.
06-29-2015, 03:44 PM
#6
Melting Slicks
When my heads were making excessively loud valvetrain noise at 2k rpm, I did a wiggle test. I wiggled each of my valves, #4 intake was moving the most. Once WCCH did a guide measure, they confirmed the #4 intake was indeed the furthest out of spec.
Not exactly definitive proof of the "wiggle", but valid enough to know if something is wrong. AFAIK, the only two methods are wiggle, or guide measure after removing and disassembling the heads.
Not exactly definitive proof of the "wiggle", but valid enough to know if something is wrong. AFAIK, the only two methods are wiggle, or guide measure after removing and disassembling the heads.
06-29-2015, 05:39 PM
#7
Melting Slicks
GM just said they would not accept wiggle test measurements as proof that the guides are out of spec. But if your guides are so far out of spec that you can easily wiggle them with plenty of play, then that should be proof enough that further inspection/fixing is in order.
06-29-2015, 11:27 PM
#8
Melting Slicks
I thought I read Katech also stated that the wiggle test was inaccurate. It makes me sick to think that shops have been recommending head replacements for a test that was "inaccurate at best" according to the most recent data. That includes GM dealers.
I do appreciate the input and your willingness to help but there is so much misinformation on this topic that when someone says "trust me" I get an uneasy feeling. Too many untrustworthy people use that phrase (no offense to you, as I have no reason to distrust you specifically).
I was hoping I could remove the head and take measurements of the guides to know if replacing them is my only long term fix for the problem, regardless of the current shape and size of the inside of the guide.
I do appreciate the input and your willingness to help but there is so much misinformation on this topic that when someone says "trust me" I get an uneasy feeling.
Too many untrustworthy people use that phrase (no offense to you, as I have no reason to distrust you specifically).I was hoping I could remove the head and take measurements of the guides to know if replacing them is my only long term fix for the problem, regardless of the current shape and size of the inside of the guide.
06-29-2015, 11:41 PM
#9
Burning Brakes
My dealer did the wiggle test and found .008. They replaced my heads. The GM adjuster came out and measured my old heads and verified the wiggle test was as accurate. There are two reasons why GM would invalidate the wiggle test, 1) some dealers were doing it inaccurately and making false warranty claims; and/or 2) damage control from legit warranty claims.
Go read Hib's article about the wiggle test.
Go read Hib's article about the wiggle test.
06-30-2015, 01:42 AM
#10
Safety Car
Thread Starter
A problem with the wiggle test is, the guide must already be deteriorating to know if you have a defective head. My engine only has 9k miles on it and I want to know that if my head checks out now, that I don't need to check it in another 10k miles.
I suppose the problem is that nobody has irrefutably determined what is actually wrong with the valves/guides. We just know that some heads exhibit premature wear that ultimately can end in disaster. Here we are 10 years since the LS7 head was born and we're still throwing parts at something 'cause nobody can figure out why they are failing. I've read oiling issues, guide concentricity, valve construction, and vague explanations like "manufacturing defect". It's amazing to me that nobody has put their finger on the issue. Maybe too many aftermarket companies have a vested interest in the FUD, and GM doesn't want to admit a mistake. :/
I suppose the problem is that nobody has irrefutably determined what is actually wrong with the valves/guides. We just know that some heads exhibit premature wear that ultimately can end in disaster. Here we are 10 years since the LS7 head was born and we're still throwing parts at something 'cause nobody can figure out why they are failing. I've read oiling issues, guide concentricity, valve construction, and vague explanations like "manufacturing defect". It's amazing to me that nobody has put their finger on the issue. Maybe too many aftermarket companies have a vested interest in the FUD, and GM doesn't want to admit a mistake. :/
07-01-2015, 11:39 AM
#14
Team Owner
If you never want to worry about the heads again, I would sell the car. High performance cars, and especially this one need more maintenance, and it looks like guides and head freshening every 20-30k miles may just be part of owning a ls7. At least checking and going from there.
07-01-2015, 02:57 PM
#16
A problem with the wiggle test is, the guide must already be deteriorating to know if you have a defective head. My engine only has 9k miles on it and I want to know that if my head checks out now, that I don't need to check it in another 10k miles.
I suppose the problem is that nobody has irrefutably determined what is actually wrong with the valves/guides. We just know that some heads exhibit premature wear that ultimately can end in disaster. Here we are 10 years since the LS7 head was born and we're still throwing parts at something 'cause nobody can figure out why they are failing. I've read oiling issues, guide concentricity, valve construction, and vague explanations like "manufacturing defect". It's amazing to me that nobody has put their finger on the issue. Maybe too many aftermarket companies have a vested interest in the FUD, and GM doesn't want to admit a mistake. :/
I suppose the problem is that nobody has irrefutably determined what is actually wrong with the valves/guides. We just know that some heads exhibit premature wear that ultimately can end in disaster. Here we are 10 years since the LS7 head was born and we're still throwing parts at something 'cause nobody can figure out why they are failing. I've read oiling issues, guide concentricity, valve construction, and vague explanations like "manufacturing defect". It's amazing to me that nobody has put their finger on the issue. Maybe too many aftermarket companies have a vested interest in the FUD, and GM doesn't want to admit a mistake. :/
You've pretty much listed all the ways to check the guide to valve clearance: wiggle test or remove the head. The wiggle test is a perfectly fine 'go' or 'no go' gauge.
I'd be checking the guides in my LS7 immediately, regardless of miles, if I were you. My 2008 had 6,300 miles on it when I checked the guides: they were out of spec!
07-01-2015, 03:16 PM
#17
Safety Car
Thread Starter
Not all LS7 engines/heads experience the same premature wear, so your comment to "sell the car" seems drastic. GM had a vested interest in making sure a wide-spread problem like this (allegedly) was fixed, as they were on the hook for warranty claims.
Since when did guides become a "wear and tear" item for unmodified engines?
7k RPM is rather common on modified LS1-LS6s.
Since when did guides become a "wear and tear" item for unmodified engines?
7k RPM is rather common on modified LS1-LS6s.
07-01-2015, 04:19 PM
#18
Team Owner
Became common when LS7s came out. GM has very little interest because the cost to fix it far exceeds what they would pay in warranty. Most cars will hit the time limit on the 5 year warranty before they get enough miles to have an issue. Hell GM let how many people die over a $2 switch so you really think they care about spending way more on fixing reliability of an out of production motor?
Either way, guides wear and need to be replaced. So what is your goal? Saying do heads once and never again isn't realistic with any motor. So is it replace guides/valve job/etc every 50k? 100k? 150k? 250k?
Either way, guides wear and need to be replaced. So what is your goal? Saying do heads once and never again isn't realistic with any motor. So is it replace guides/valve job/etc every 50k? 100k? 150k? 250k?
07-01-2015, 06:59 PM
#19
Le Mans Master
Became common when LS7s came out. GM has very little interest because the cost to fix it far exceeds what they would pay in warranty. Most cars will hit the time limit on the 5 year warranty before they get enough miles to have an issue. Hell GM let how many people die over a $2 switch so you really think they care about spending way more on fixing reliability of an out of production motor?
Either way, guides wear and need to be replaced. So what is your goal? Saying do heads once and never again isn't realistic with any motor. So is it replace guides/valve job/etc every 5k? 10k? 15k? 25k?
Either way, guides wear and need to be replaced. So what is your goal? Saying do heads once and never again isn't realistic with any motor. So is it replace guides/valve job/etc every 5k? 10k? 15k? 25k?
07-01-2015, 07:19 PM
#20
Team Owner