CD 31 Universal (Westbeke) 25 h-3 cyl diesel/need help

[Chris Shultz]

On our CD 31 cutter our 83 Universal (Westbeke)25 horse/3 cyl diesel Model #5424 is overheating. I have replaced the fresh water pump (necessitated due to bent impeller shaft.) Removed thermostat to see if it was opening, still overheated. note:raw water system OK. Anybody got any ideas?? Suggestions?? We sure would appreciate any thoughts on the matter.



Oversear@nh.ultranet.com

[Tom]

On our CD 31 cutter our 83 Universal (Westbeke)25 horse/3 cyl diesel Model #5424 is overheating. I have replaced the fresh water pump (necessitated due to bent impeller shaft.) Removed thermostat to see if it was opening, still overheated. note:raw water system OK. Anybody got any ideas?? Suggestions?? We sure would appreciate any thoughts on the matter.

One thing that it took me a long time to figure out, and will make you boil over every time is if you get an air bubble in your coolant. There is no way to avoid this if you've removed your fresh water pump. It inevitably introduces air into your coolant. The cure is not pleasant although easy to do. The air bubble traps itself in the highest part of the system which is the hot water tank. The only way to get it out of there is to blow back through the hoses that connect to the overflow tank. I can't remember which hose it is that does it -- I think it's the bottom one on the heater, but I'm not sure so do both to be sure. Pull the hose off at the reserve tank (put your thumb on the tank bib) and blow mightily (you have to blow HARD!)into the hose. You will probably hear it bubbling back in the heater. This forces the coolant up against the top of the heater and somehow forces the bubble into the coolant stream and it works its way around and out through the overflow tank. Re-hook the hose and run the engine (sometimes you'll see the bubbles come up in the reserve tank) Do this several times and voila no more overheating. Hard to believe that a little tiny bubble will overheat the engine, but it DOES! Ethylene Glycol (coolant) is poison, of course, so you try not to swallow any of it while blowing. A little bit on your lips won't hurt you -- I know I've done this many times.
Another overheating cause is when your "radiator" cap on the engine loses its spring. It allows coolant to leak when the engine is hot and then overheat your engine. In this case however you notice that the coolant keeps getting low. That doesn't sound like what you've got. I'd bet anything you've got an air bubble because I've been there and done that and a clever mechanic in North Carolina figured out what was causing it for me. Since then I've had to do it many times -- whenever you take the engine out, whenever you replace a hose,and especially when you replace the pump. Having a bubble is just like a thermostat that doesn't open - it stops the flow.



TacCambria@thegrid.net

[Joe Sankey]

On our CD 31 cutter our 83 Universal (Westbeke)25 horse/3 cyl diesel Model #5424 is overheating. I have replaced the fresh water pump (necessitated due to bent impeller shaft.) Removed thermostat to see if it was opening, still overheated. note:raw water system OK. Anybody got any ideas?? Suggestions?? We sure would appreciate any thoughts on the matter.

This is a long shot, but I replaced everything on our Universal 14 hp (CD28) before we happened to notice the short hose to the thermostat housing; it had delaminated around the wire coil and was acting like a check valve when the coolant started flowing faster. I'm not familiar with your engine but if it has this short hose, you might inspect the inside of it.
Joe



sankey@gulftel.com

[tony raymond]

I would start with removing and inspecting any hoses for interior delamination. Next, visually check the heat exchangers for cleanliness. What about prop loading. Did you recently change it, damage it or wrap a line? Other causes might be exhaust elbow blockage/restriction or bad injectors. You didn't give much info on the conditions when it over heats, so I'm just throwing ideas.

Good luck
Tony



tony.raymond@worldnet.att.net

[Carl Forsberg]

I have owned a 1984 Cape Dory 31 for ten years. During that time I have received three modification bulletins from Westerbeke on the Universal Model 25 diesel engine. One bulletin referred to overheating problems, which I was having, big time, on a trip down the ICW from Maine to Florida, after I left those 50 degree Maine waters, any time I exceeded 2000 rpm. They recommended changing the 2 inch heat exchanger for a 3 inch, which I did. The problem went away. The fit is tight. They will sell you the part. Installation is straight forward.



Forsberg2@juno.com

[Bonnie Radke]

We have the same engine for our CD 31. This year we replaced all the hoses to the engine as well as impeller(saltwater pump). We had noticed a slight scoring on the impeller shaft which we smoothed off. In doing so we left a slight space for water to seep out. When we started the engine it would over heat as well as lose its prime. We took the saltwater pump apart, replaced the impeller shaft and also what they called in the manual, an oil seal and a water seal. They are very hard to remove but when we put the pump together again everything worked great. Apparently that has to be very tight to pump out the correct water. If you need a picture of the parts manual contact me directly and I can scan it in and send it to who ever needs it. Good luck.



seawitch2@aol.com