what percent of c6 ls7s drop valves?
05-09-2018, 04:15 PM
#41
I took my Z to a Chevy dealer that is very familiar with the valve guide problem. I had them do the wiggle test to give me an indication of whether or not the valves seemed to be out of spec. If the valves seemed to be in spec, I was going to have to pay for the wiggle test. But both times I had the test done, the valves were deemed to be out of spec. The first time was 5 years ago and the heads were replaced with new GM heads that lasted 23,000 miles. A lot has been learned in the last 5 years and GMPP now works with AHP so we can get their fixed heads. You're not that far from AHP, call them.
05-09-2018, 06:05 PM
#42
Melting Slicks
Yes I get that, but the chances of them blowing are minuscule, I'm sure you get that.
You can call it the luck of the draw but when I am a part of the 95% who never had an issue I was willing to take those odds. Was I just flat lucky being a part of 95% or were those who were a part of the less than 5% very very unfortunate. Take your pick. You decided to fix yours and that is great. I decided to never touch mine and it worked out for me. If you notice on any post I make I never tell anyone to NOT fix them. I tell them for their peace of mind if they want to they should!
If they do not, then enjoy the car and drive the heck out of it.
You can call it the luck of the draw but when I am a part of the 95% who never had an issue I was willing to take those odds. Was I just flat lucky being a part of 95% or were those who were a part of the less than 5% very very unfortunate. Take your pick. You decided to fix yours and that is great. I decided to never touch mine and it worked out for me. If you notice on any post I make I never tell anyone to NOT fix them. I tell them for their peace of mind if they want to they should!
If they do not, then enjoy the car and drive the heck out of it.
05-10-2018, 01:41 AM
#43
Burning Brakes
I have confidence in three things:
1) the majority of LS7's don't fail catastrophically.
2) the valve guide issue is real, and can lead to (eventual) failure.
3) the majority of failures are "likely" aggravated / propagated by track use.
Internet "statistics" is one thing. However, if I look around at my LOCAL circle (in Canada, of all places, which has ~1/10th the car population as the USA), I can count a number of LS7 owners who I know (or know of) that have had engine failures, MYSELF INCLUDED.
Almost all of the "failures" that I know of around here, have happened at the track, or subsequent to tracking. Mine ('06Z) occurred on-track (less catastrophic than dropped valves, but was down ~2+qts of oil after 2 track sessions, and wiped the main crank bearings).
Outside of "failures", there have been a number which have been inspected and confirmed out-of-spec. My new (to me) '11 Z is in that club, and the heads are currently being fixed.
So what's the percentage??? My thoughts are "quite high" for guides out-of-spec. However, actual engine FAILURES is probably quite low, as MOST cars do not get pushed/abused to their fullest potential, thus, the guide wear can be tolerated for thousands of miles without notice or apparent "issue".
That's my $.02.
1) the majority of LS7's don't fail catastrophically.
2) the valve guide issue is real, and can lead to (eventual) failure.
3) the majority of failures are "likely" aggravated / propagated by track use.
Internet "statistics" is one thing. However, if I look around at my LOCAL circle (in Canada, of all places, which has ~1/10th the car population as the USA), I can count a number of LS7 owners who I know (or know of) that have had engine failures, MYSELF INCLUDED.
Almost all of the "failures" that I know of around here, have happened at the track, or subsequent to tracking. Mine ('06Z) occurred on-track (less catastrophic than dropped valves, but was down ~2+qts of oil after 2 track sessions, and wiped the main crank bearings).
Outside of "failures", there have been a number which have been inspected and confirmed out-of-spec. My new (to me) '11 Z is in that club, and the heads are currently being fixed.
So what's the percentage??? My thoughts are "quite high" for guides out-of-spec. However, actual engine FAILURES is probably quite low, as MOST cars do not get pushed/abused to their fullest potential, thus, the guide wear can be tolerated for thousands of miles without notice or apparent "issue".
That's my $.02.
05-10-2018, 08:44 AM
#45
I have confidence in three things:
1) the majority of LS7's don't fail catastrophically.
2) the valve guide issue is real, and can lead to (eventual) failure.
3) the majority of failures are "likely" aggravated / propagated by track use.
Internet "statistics" is one thing. However, if I look around at my LOCAL circle (in Canada, of all places, which has ~1/10th the car population as the USA), I can count a number of LS7 owners who I know (or know of) that have had engine failures, MYSELF INCLUDED.
Almost all of the "failures" that I know of around here, have happened at the track, or subsequent to tracking. Mine ('06Z) occurred on-track (less catastrophic than dropped valves, but was down ~2+qts of oil after 2 track sessions, and wiped the main crank bearings).
Outside of "failures", there have been a number which have been inspected and confirmed out-of-spec. My new (to me) '11 Z is in that club, and the heads are currently being fixed.
So what's the percentage??? My thoughts are "quite high" for guides out-of-spec. However, actual engine FAILURES is probably quite low, as MOST cars do not get pushed/abused to their fullest potential, thus, the guide wear can be tolerated for thousands of miles without notice or apparent "issue".
That's my $.02.
1) the majority of LS7's don't fail catastrophically.
2) the valve guide issue is real, and can lead to (eventual) failure.
3) the majority of failures are "likely" aggravated / propagated by track use.
Internet "statistics" is one thing. However, if I look around at my LOCAL circle (in Canada, of all places, which has ~1/10th the car population as the USA), I can count a number of LS7 owners who I know (or know of) that have had engine failures, MYSELF INCLUDED.
Almost all of the "failures" that I know of around here, have happened at the track, or subsequent to tracking. Mine ('06Z) occurred on-track (less catastrophic than dropped valves, but was down ~2+qts of oil after 2 track sessions, and wiped the main crank bearings).
Outside of "failures", there have been a number which have been inspected and confirmed out-of-spec. My new (to me) '11 Z is in that club, and the heads are currently being fixed.
So what's the percentage??? My thoughts are "quite high" for guides out-of-spec. However, actual engine FAILURES is probably quite low, as MOST cars do not get pushed/abused to their fullest potential, thus, the guide wear can be tolerated for thousands of miles without notice or apparent "issue".
That's my $.02.
GM designs engines with a 300k mile life expectancy. So if you have guides out of spec at 10, 20, 30k miles then yes thats technically a parts failure. Out of spec guides will eventually lead to a dropped valve given enough time.
Your last point makes no sense though I'm sorry. I have seen more valve failures in bone stock cars idling down the roadway than anything else. If anything it seems the track cars hold up better than the garage queens.
My bone stock car with 16k on it which had never been driven out of its hometown let alone on a track had every single guide out of spec.
05-10-2018, 12:17 PM
#46
Burning Brakes
I'm completely on-board, there IS an issue with the guides. The number affected may literally be 100%. So we could argue that 100% of LS7's are a ticking time-bomb, but how many of them have been driving around for thousands of miles and have yet to actually fail?? LOTS!! Point being, the number of outright failures/dropped valves is a much smaller percentage than the total number of LS7's on the road.
As for the street driven cars having worn guides ............ absolutely .......... never doubting or arguing this point for a moment. But my belief is that, while the guides ARE wearing, the odds of dropping a valve are MUCH LOWER while cruising on the street than they are if you're pushing an engine on the track which is suffering from worn guides.
Sorry if it seems I'm arguing semantics. Somewhat, YES, but the OP's question related to "what percentage of LS7's drop valves", and as of yet, the number is far from 100%.
05-10-2018, 12:33 PM
#47
Drifting
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