While test running my Fat 50 motor in a 55 gal drum I noticed that the #2 and #4 cylinder side was running about two times higher than the temperature of the #1 and #3 side. The motor seemed to be running OK and there was a water mist coming from the upper exhaust port. I stopped the engine and disconnected the hose leading to the thermostat by pass housing and restarted the engine, it took a couple of seconds or so but water did come out of the #2 water outlet port and within a short time I had full flow out of that port. Rechecking the head temperature I found that it had dropped to the same temperature as the #1 side. I looked for in my service manual for any service info and only found some information about the thermostat housing. I did remove the thermostat housing and disassembled the unit and found little bit of weed seeds on the seat of the secondary bypass port. I am wondering if there isn't enough water pressure to maintain adaquate water flow. I did have the lower unit off and did examine the water pump housing, I found the impeller looked good but there was some minor wear in the upper part of the pump housing. I just aquired this engine and the previous owner took no pride in maintaining this beautiful old engine. It amazes me that after all this time that with a little bit of care that it runs as well as it does. Any information on this problem will be greatly appreciated, thanks so much.
