I had overheating problems with my W50, but I now think I have them solved. The following is a listing of what I did. I can't say that there was one thing the fixed the problem, but I've found from the past that overheating can be caused by a number of small problems, on there own not significant, but when combined cause overheating.
Two years ago I couldn't run the engine greater than ~ 1800 rpm without beginning to overheat. To solve this problem, last winter I did the following:
1. Cleaned the Heat Exchangers: I removed the FW/RW heat exchanger and the lube oil cooler, and had both 'boiled.' I had it done at a radiator shop, and both heat exchangers came back like new. Unfortunately, you need to remove the exhaust manifold to remove the FW/RW heat exchanger. Its not hard - just awkward to do. While you're at it, you can inspect the exhaust elbow for blockage (seawater flow in and/or exhaust). I had none.
Note that there is a rubber 'inspection cap' that goes over the aft end of the FW/RW heat exchanger. Be sure that you get it on correctly. There is a groove in it that needs to fit over the heat exchanger's divider plate. If its on wrong (i.e., water is allowed to bypass the divider plate), you can seriously reduce the heat exchanger's cooling capacity. Its hard to put on correctly with the heat exchanger on the bench; its almost impossible to replace correctly with the heat exchanger on the engine!!!!
While the heat exchangers are out, be sure to replace the zincs.
2. Rebuilt Raw Water Pump: I replaced all items that could affect the pumps capacity: the impeller, cam, cover plate, and back wear plate. Eventhough the ones that were in the pump looked 'OK', it seamed that replacing those items did improve sea water flow. 3. Replaced Water Lines: I replaced all the water lines, both raw water and engine coolant. 4. Cleaned Intake Thru-Hull: Years of bottom paint had partially blocked the intake strainer on the thru-hull. I cleared the slots with a screw driver. 5. Rebuilt the Fresh Water Cooling pump: I had some minor seal leakage so I had the FW pump rebuilt (bearings and seals). A new pump from Westerbeke is about $350. I had mine rebuilt for less than $75, so you may want to do the same. 6. Replaced the coolant:m If the coolant isn't close to 50-50 water to antifreeze, the heat removal capability of the coolant is deminished. 7. Replaced the thermostat: It was working fine, but seemed like a good idea to replace it while I was at it.
After completing all the above, I thought I had my cooling problems solved. Last spring when I launched the boat, I could run the engine indefinitely at 2200 rpm, and the coolant temperature held solid at 180F. I never run the engine greater than 2500 rpm so I don't know how it would have responded at those higher loads. In the Spring at launch, the seawater temperature was about 55F. During the summer, however, as the seawater temperature rose to 65-70F, I noticed that the engine was running slightly warmer at 2000-2200RPM. It never lead to any overheating, but troubled me after all the work I had done.
Well, this winter I pulled the raw water pump to replace the shaft seal (I had slight leakage). Much to my surprise, when I tried to blow air through the discharge fitting (elbow) on the pump, I noticed there was an obstruction. I couldn't see anything from either end of the elbow, so I took the elbow off the pump an 'rodded' it with a stiff piece of wire. I found 3 rubber ends of a failed impeller jambed in the elbow. Those could have been in the pump for years, since I hadn't had any impeller failures. After removing these pieces, I'm surprised I didn't have severe overheating!! Anyway, with those obstructions removed, I convinced that all my cooling problems are now gone. I'm eagerly awaiting next summer.
If anyone, would like to discuss, feel free to contact me off-line.
Jim Voelxen Odessey T37C #191
_________________ Jim Voelxen Odyssey #191 Home Port: Osterville, MA
Last edited by jvoelxen on 09 May 2008 14:23, edited 1 time in total
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