Westerbeke Issue - Salt water in coolant tank

[egaito]

I'm guessing I already know the answer to this, but thought I'd throw it out there to see if there are other causes and solutions we might be able to deal with here in Bimini.

It appears the coolant in the genset has been replaced with salt water. First reaction is a blown heat exchanger, but are there other causes that might lead to this?

It shut down automatically, which got us checking things. Oil was approaching the low mark, but not quite there, so it's possible this was the sensor that shut us down. There is no water in the oil. Ang went down while I was dealing with the power pedestal, which happened to go bad at the same time. The genset was hot, but she didn't smell anything "burning" or that unique overheat smell. What she describes sounds normal for a unit that's been running all day.

I found this on another forum, but haven't checked it out yet.

At each end of the heat exchanger are rubber caps with two hose clamps. The small clamp keeps sea water in the heat exchanger tube and the large clamp keeps the anti-freeze in the cast iron body of the exchanger. If the small clamp isn't put on just right, sea water will leak around it and go into the antii freeze and fill up the reservoir. When it fills up water comes out the pressure relief hose and goes in the bilge. If your Westerbeke has same setup, make sure your small clamp is on tight.​

So, a couple of questions:

While it's not good for it, there's already salt water in the cooling system....is it safe to run at all for the trip home>

Any other causes for this that folks have seen other than a bad heat exchanger?

Anyone want to drop one off in Bimini for us?

Thanks,

-Ed G.

 

[REBrueckner]

As long as there is no salt water in your lube oil, running the genny with some salt water in the cooling system should do no harm....it's a corrosion concern, a long term issue....flushing out the cooling system is of course required before you refill with clean coolant or maybe distilled water and antifreeze.

I am not familar with Westerbekes specifically , but it should be easy to pressure test your heat exchanger when you are ready to isolate the trouble. Or maybe you can remove the raw water connections, and pressure test via the radiator cap on the expansion tank of the genny....you can even color the coolant water and see if any appears in the heat exchanger....

 

[egaito]

Thanks for the reply Rob.

I'm going to pull one of the end caps off and make sure there's no zinc or impeller garbage in it to maximize circulation and give it a whirl, see if she stays cool.

We'll pull it off back in Miami, and likely just replace it as they aren't repairable (to my knowledge) and I don't think there is any other explanation for the symptoms we're seeing.

Now, back in the hole....

 

[REBrueckner]

" I don't think there is any other explanation for the symptoms we're seeing."

I think so ...I should have explicitly said that....raw water only touches a cooling system in gennys at a very few points...in a typically genny it's the separately mounted external heat exchanger only ...and in some ONANS, the gear driven raw water pump..as on the 7.5KW models of the 1970's....maybe other years...

On my 12 KW Onan for example, the heat exchanger is separately mounted and that's the way I saw it on the only Westerbeke I ever worked on...a 1986 Marine Trader of a slip mate....

good luck....

 

[egaito]

Ours is as you described. It is a separately mounted tank (Sen-Dure I believe) with Fresh and raw water in and out.

I removed the end caps and cleaned out a lot of crap (zinc residue), opened up some holes that were clogged, fixed a couple of leaks and a bad clamp that I didn't know were there, and put it back together. I could see the thermostat working and it held 180 degrees with a 30 amp load for about 20 minutes, so I've deemed it good enough to get home.

Interestingly, watching the temp gauge, I could see it going above 180 for a few seconds, and dropping back to 170 or so periodically. Not sure if that's the thermostat "cycling", pump cavitation, or a symptom of the internal issue with the exchanger. Makes me want to watch her work more closely once the new one is installed.

 

[Fanfare]

Dump the water, replace with fresh. Maybe bottled rather than Bimini tap water which used to be brackish. Won't hurt the gen on the trip back. Repeat as needed if you are staying over in the Bahamas. Salt water precipitates out in cooling systems at 180* which is why raw water cooled engines generally have 160* thermostats. I don't think this would bother it for the short time you will need it. Flush and repair when you get back.

Hope you are having a great time. Congratulations on the voyage!