lucknow
New Member
Hi all:
My 1989 340 express cruiser has twin 454's with closed coolant systems, it has been repowered and the motors have 300 hours on them. Starting last year, I loose 1/2 gallon of coolant on the port motor after approx 3 hours usage. There does not appear to be any external leak, there is no coolant in the bilge beneath motor, the engine runs fine, no misfires, do not think it is entering the cylinders, the hot water heater is hooked up to that motor, no signs of coolant in the heated water. no signs of leak at the circulation pump on motor, no excessive steam out of exhaust while running, in fact the steam is the same as starboard motor. Now here is the strange part, If i use the boat and then park it for a week. when I return and check the coolant level, the coolant system is still pressurized. The leak does not occur when motors are not running. It lost no coolant over the winter, I swapped heat exchangers from side to side and the leak remains on the port side. I left a pressure tester on the coolant system when cold at 15 lbs and it did not lose pressure after 2 hours. I am thinking it must be leaking from exhaust manifold, but I would think there would be coolant pressure loss after engines are turned off. I am out of things to check, I am considering putting a sealant in that motor to see if it stops the leak. Has anyone got any ideas or suggestions?:smt100
My 1989 340 express cruiser has twin 454's with closed coolant systems, it has been repowered and the motors have 300 hours on them. Starting last year, I loose 1/2 gallon of coolant on the port motor after approx 3 hours usage. There does not appear to be any external leak, there is no coolant in the bilge beneath motor, the engine runs fine, no misfires, do not think it is entering the cylinders, the hot water heater is hooked up to that motor, no signs of coolant in the heated water. no signs of leak at the circulation pump on motor, no excessive steam out of exhaust while running, in fact the steam is the same as starboard motor. Now here is the strange part, If i use the boat and then park it for a week. when I return and check the coolant level, the coolant system is still pressurized. The leak does not occur when motors are not running. It lost no coolant over the winter, I swapped heat exchangers from side to side and the leak remains on the port side. I left a pressure tester on the coolant system when cold at 15 lbs and it did not lose pressure after 2 hours. I am thinking it must be leaking from exhaust manifold, but I would think there would be coolant pressure loss after engines are turned off. I am out of things to check, I am considering putting a sealant in that motor to see if it stops the leak. Has anyone got any ideas or suggestions?:smt100