I recently had the engine on my 2013 G37xS coupe swapped out for a VQ from a 2014 q60 with 78k miles, due to my gallery gasket giving out. Now less then a week later, my G broke down again mid-drive. This time was due to the flexplate snapping. Specifically, where the crankshaft bolts attach to the plate. You can see the break in the picture below:



From my understanding, flexplates can break from age/metal fatigue, but also from uneven and improper torquing of the bolts. My mechanic claims its due to metal fatigue and age, but I want to get other opinions on whether this looks more like a break from fatigue or from improper installation.

The flexplate is the original from the car and had 110k miles on it.

I've requested for pictures of everything once the mechanic starts to take it apart, as well as the old flexplate pieces. I don't want to accuse my mechanic if this wasn't his fault, but I also don't want to get screwed out of another big chunk of money.

Could anyone help shed light onto this? Or share their opinions?

Thanks!

 

I have heard that the OEM flexplates are weak in the context of 500+ WHP forced injection builds (Soho will say this, as well as IPT), but I have seen very few flexplate failures reported as most of us are just naturally aspirated with some bolt ons.

 

My flexplate broke a few years ago. I was redlining with the paddles a lot though, cause that's where most of the power is and it won't let you get to that if you keep it in auto. With that many miles I don't see how they can blame the mechanic unfortunately. I just use stop leak for my leaking gaskets. https://barsleaks.com/product/oil-se...k-repair-os-1/

 

The stock flex plate is a design flaw. 300 hp with that thin metal? Mine went out at 130K. Put a good one in from Z1 Motosports.
That was a corner they cut for profit. Yes i drive it hard at times. Thats why i bought it. If i wanted to ease around i would have bought a KIA.