I pirsonaly would not heat the engine i would defenatly try some solvents first just be very cearfull if the crank has the red puddy in it mitneral sprits will not efect the puddy but some stronger solvents will. If the crank has no red puddy in it id use somthing more agressive, i would defenatly try to disamble the engine first if posable and leve the piston liner and conrod soke in some solvent. Just be cearfull with of the crank if there is red puddy in it do not use any kind of spray cleaners it will attack the puddy. good luck Regards Jeremy.