Its really annoying to add something like this and not give people the option to turn it off or on especially when modding its really annoying to have cars overheat in 5 seconds its not realistic at all i know your going to tweak it in the next updates but PLEASE give us a option to turn it off in the tuning menu or something or at least inscrease the cooling system efficienty with better parts Unless these cars are running on the surface of the sun there is no reason why they would overheat and explode this quick.
You can As you mentioned, thermals get annoying when modding. In the engine jbeam, there is an option to turn it off. I forgot the exact name, but it's above the engineblockdamagethreshold Something like that
No way to disable that for the time being. You can edit the vehicle files as said above, but expect that to cause problems and irregularities at the next update. Some radiators were made more effective and resistant for the next update. If you are trying to put an high-powered engine on a car, don't forget to select the high-performance radiator aswell. If you are modding a vehicle power, having it to overheat if you are still using the standard radiator is to be expected.