Over revs always equals engine damage?

[b8575]

Was watching the start of this video https://youtu.be/22jTQYm9s7Q where they're talking about rebuilding an engine because it had a report of over revs but, even though it was stripped down completely, they were yet to find an issue with it. Which begs the question, why spend all that time/money rebuilding it?

I'm guessing that all/most manual cars can suffer from a miss shift, leading to an over rev, but Porsche cars record them (I think BMW May too) so other manufacturers' cars are only fixed if the over rev results in actual damage.

That got me thinking, is this mainly a way for manufactures to get out of paying for a warranty fix? I wonder how many cars that have had some sort of over rev have actually had an engine failure?! Is it really the case that a high over rev = engine damage?

 

[sja360]

I guess they have to put it as a get out clause. They haven't tested the engine with constant over-revs and checked for damage. So they wont be likely to cover it.

In all honesty i am not sure how much this would really damage the engine. Surprised to see a mezger engine being stripped though. Did the owner have an actual issue with it ?

 

[Magic919]

Without any data it's largely guesswork. Maybe they have the car and want to sell it as used stock.

A Mezger can usually rev to 8400 I think. If it's just range 1 that could be up to 9200 rpm. Range 4 is 9600+ and they say damage is probable. Then there's 5 and 6.