So--- my wife brings our 90 model montero home the other day saying it was running a little hot. So I checked and it was low on coolant. Filled it up and started it and it starts steaming ot of the exhaust. I pull it in the garage and hook up an air line into each cylinder and pressurized each one individually. Saw no bubbles coming out of the radiator. Could this be a problem with an intake manifold leak or ?? Any help would be great.