So my main topic of discussion and question is about what causes head gaskets to fail. My head gasket is leaking and I'm planning to replace it but I have to find out what caused its failure in the first place. Can somebody give me some common things to look for other than over heating?
Also my coil pack was bad and it took me a while to figure out that was causing issues with my motor. It was the usual cylinder three port on it that was bad. Could that possibly cause head gasket failure? To be more specific about my car it's an 03 R50 that just had a motor swap done about 8 months ago. I supposedly swapped in another 03 R50 mini cooper motor with about 40k miles on it. I unfortunately don't have any paperwork about the motor I had swapped in only my mechanics word on it which isn't worth much. Any input provided is appreciated thanks for reading my post!!

A little additional information while trying to figure out what was going on with my car as it was throwing a cylinder three misfire code we did a new coil pack, spark plugs, spark plug wires, and fuel injectors. When pulling spark plugs the ones that were in cylinder three and four had some gasoline on them. I definitely wouldn't say they were soaked with gasoline but it was there.
Later on while trouble shooting the next weekend an odd occurrence happened. I threw seafoam in the engine and it made it run like trash. So we parked it and attempted to siphon out the gasoline. We'd planned to do a fuel filter and put fresh gasoline in it. When we attempted to siphon out the gas there was no gasoline in the tank. We tried from the outside and also from under my fuel filter housing while I was replacing it. My gas gauge on the other hand stated I had a half a tank. I don't know if any of this information is helpful so my apologies if it isn't.

 

Overheating is the usual cause of a blown head gasket.

 

It was a false economy to not replace the Thermostat/Thermostat Housing when the motor swap was done, and after an inspection of the water pump, possibly that as well. There is a high level of correlation between engine failures after swaps due to the engine overheating (directly related to thermostat failure).

Overheating, causing the head-gasket to fail, possibly causing warped head, possibly causing burnt valve(s) ...

Fuel filter... did you replace the canister filter or the filter on the fuel pump? (passenger side or driver side?)

I generally crack the fuel line loose at the fuel rail to bleed the air out of the line after replacing the filter (passenger side).

Best of luck with your repairs.

Motor On!