Hi guys! Hoping someone can point me in the right direction here cause I’m at getting a bit frustrated . I got a 1981 Johnson 50hp I’ve taken over from my old man as he’s just left the boat in the bush for 5 years and it’s a damn shame. I took it out on the water for the first time and it ran alright for a bit but overheated near end of run. Took home.. replaced water pump and thermostat was stuck open so replaced it too. Second time out and it ran ok at first but overheated again. Ripped it right down (removed power head and lower unit, opened water passage), found it had a blown head gasket. Replaced all gasket and cleaned out everything. Put a straight edge on head and has very minor warp but nothing I was concerned about. Anyways got it all back together (torqued to spec), put the ears on and after about 5 minutes she overheated again! Thermostat confirmed working. There is no pressure release valve, it’s been silicones over. Any ideas gentlemen? Thanks and sorry for the long post.