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BLOWN MOTOR: Lucky for this guy he still has remaining warranty
My Service Adviser brought me back in the shop and showed me this today. C7 Z51 M7 Trans. I don't know the "circumstances" that lead to this, but HOLY COW!! The valves and a lot of the head pieces. He did say the peak rev's were in the 8,000 range.
I was told they are covering it under warranty. Good for him. I'm glad I found a dealer that doesn't always look for reasons to charge loyal customers. They said they can see peak rev value, but not the duration. It won't be long before the system will record all kinds of events like a black box recorder so they can see all sorts of parameters such as gear, speed, etc.
Last edited by stevettec7; 12-21-2017 at 06:08 PM.
I was told they are covering it under warranty. Good for him. I'm glad I found a dealer that doesn't always look for reasons to charge loyal customers. They said they can see peak rev value, but not the duration. It won't be long before the system will record all kinds of events like a black box recorder so they can see all sorts of parameters such as gear, speed, etc.
It's always nice to find a dealer who tries to help customers as much as they can. However, things like this are usually out of the dealer's hands after major failures. GM usually wants to see certain things before agreeing to approve such warranty repairs and reimburse the dealer. A dealer has no control over that.
I also agree this was probably an ill-advised or botched downshift. The rev limiter protects the engine going up, but not from an over-rev on a downshift.
Wow - can they actually track at a point in time what the max RPM was? If so, I agree it could only be a botched downshift - or a tuned car that for some reason removed the rev limiter.
Wow - can they actually track at a point in time what the max RPM was? If so, I agree it could only be a botched downshift - or a tuned car that for some reason removed the rev limiter.
If it were a tuned (now or previously) car, we'd for sure be talking about a warranty denial. If this repair has been approved, that means GM has already examined the ECM data.
Originally Posted by spireland
Some dumb questions.....
Wouldn't the rev limiter prevent you from going to 8k?
Does the engine taper off in torque and HP massively at that point?
The rev limiter protects an engine going up the rev curve, but it can't possibly stop an over-rev when someone downshifts to 2nd at say 80 mph. The gearing will mechanically over-rev the engine, and no electronic device cutting the spark can stop that carnage.
Peak HP and torque happens and begins to drop well before redline, so no reason to go there.
The only way stop an over-rev on a downshift would be to put an electronic block, a la CAGS, disallowing downshifts at certain speeds and rev ranges. And, of course, everyone would be immediately looking for a way to defeat it.
Quite frankly, it takes a pretty bad driver to do something that ridiculous. The shift gates essentially block such radical downshifts, unless somebody purposely forces it.
12-21-2017, 05:05 PM
BLOWN MOTOR: Lucky for this guy he still has remaining warranty
Maybe not defeat it if they once blow their engine and it's NOT covered. Like this one probably won't be. Maybe.
