My rusty old 1959 gas Perkins blew half the exhaust gasket out of the front cylinder, I've been using it that way for 5 years. I've tried several times, with the engine hot, to loosen any of the manifold bolts, no luck. I use it often so don't want to open a big can of worms by breaking any off (holds the intake on too I believe). The leak is easy to get to, I tried some muffler patch which lasted about 5 minutes, then some other supposedly better stuff from the auto parts store that lasted about a day. I've heard of guys using furnace repair glop. Is there anything that actually works? I just put a new muffler on so now it's sounding pretty loud.