Got a customer's car that broke 2 pistons and bent 2 conrods about a month ago. Customer took the car to another workshop to do the repairs, they replaced 2 pistons, 2 conrods, one valve that broke off the head and got jammed into one of the pistons, the cylinder head was damaged and broke a water gallery that caused the customer to keep adding water prior to the final demise of the engine and as he stated the water kept disappearing, which means there was already some sort of cylinder head damage occouring and water mixing in the sump (hydro lock?) When the engine broke the engine locked and seized.
Now a few weeks after this was done they have called saying the flywheel came off the crank, sheared all the bolts clean off the crank. They claiming we did the clutch repair back in June this year and the flywheel wasnt torque'd right which is BS as the remaining bolts in the crank are still in place with loctite and were torque'd as per the manufacturer specs with new bolts i might add.
Hi and thanks for contacting YourMechanic. When an engine is seized at an instant, especially when the engine is under a load, the flywheel will cause a big jolt. Now, the weight of a fly wheel is heavy when it comes to a rotational direction. With that said, as the engine is stopped at an instant, the flywheel will continue to rotate. If the bolts were new, the flywheel may survive the engine damage and just crack one or two bolts. However, if the bolts are used and old, then the flywheel will shier off the bolts. This has nothing to do with a loose bolt. A loose bolt will cause a vibration and make a ticking noise as the engine is running. In my career, I have seen cracked and broken flex plates, but have not had a flywheel come off due to non-torqued bolts with locktite on them.
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