Our original Westerbeke 50 has had an overheating issue when running at anything over 2/3 speed. So far I have replaced the impeller, barnacle buster'd the freshwater side, checked elbows and other areas that might catch debris, checked the mixing elbow, and replaced the thermostat, all with very minimal results.
This off season I've gone ahead and pulled the manifold and heat exchanger for inspection.
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IMG_20240114_080805_405.jpg [ 168.79 KB | Viewed 0 times ] When I pulled the heat exchanger, I was almost excited to see the large amount of debris build up on the forward end that connects to the manifold.
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IMG_20240114_080806_915.jpg [ 138.62 KB | Viewed 0 times ] I figured that if there's that much debris clogging that spot, it's probably all throughout the heat exchanger so I've gone ahead and replaced it with a version from Mr. Cool.
It's still the dead of winter here so I haven't run the engine yet to see if there is any change but I'm fairly certain this will have a decent impact on the running temp. This has been the only obvious thing I've come across so far.