When you tell the equipment owner to disassemble the engine or other mechanical component to determine and report back what is wrong and what it will cost to repair, you have authorized him to destroy all the evidence that could have been used to prove that the equipment failed and this is not a valid claim. We routinely conduct Root Cause Analysis on engines, transmissions, axles, hydraulic pumps & motors and can attest to the difficulty when the item has been tampered with before we have the opportunity to inspect it.
We recently handled a claim where the insured claimed vandalism. After a two hour inspection meeting where it became clear to him that we were sufficiently knowledgeable with his machine and that we doubted the likelihood that his failure was a consequence of vandalism, the insured withdrew his claim.
The subject of the above photo and those below was a 2005 Subaru turbocharged, aftercooled engine. We don't normally "do cars", but this was a challenge we couldn't resist. The shop submitted this claim to their garage keepers insurer when this motor croaked shortly after the shop installed a new oil pump and water pump for what they insisted was preventative maintenance. Nothing about their story added up. During our investigation we discovered the engine had been overhauled about a year previous to this "loss" and there was no evidence the break-in oil was ever changed. Using fluid analysis, filter cutting and our expertise, we were able to prove that the failure was not sudden. The claim was denied. The insured contested the denial. Our report was subjected to peer review and the engineer agreed with our findings. The denial was sustained.