Westerbeake 71C overheating

[Lyn Hancox]

Wonder if anybody can assist? Our Westerbeake has had overheating issues for a little while now and wishing to go out for a couple of weeks needs to know if any damage will occur if we run the engine for lengthy periods without the thermostat in? For background info, there is plenty of raw water, the heat exchanger is clean as are all the hoses. Oil is fresh and at the correct level with normal pressure, no obstructions to the prop. No oil in the water and no water in the oil, exhaust appears OK. Engine hours 2626. Air intake clear. Tried three new thermostats but each one seems to be restricting water flow so she overheats within a few minutes of load. Take thermostat out runs fine but obviously cool.

[a64pilot]

It won't kill it, but you need to find out what s wrong, From your description it sounds as if your fresh water pump's impeller is worn somehow or something similar to decrease water flow to below what is required. IF that's the case, then it may let you down at the worst possible moment.
First I would absolutely verify the your thermostats are the correct temp, then verify your temp gauge. Is it possible your engines fine, but the temp gauge isn't?

[Lyn Hancox]

Thanks for the advice A64pilot

Don't need to check the instruments as the engine rapidly boils pushing coolant out through the header tank! Seems to be air locking all the time when the thermostat is in place but does not when I remove the thermostat without the thermostat fitted engine will hardly warm up at all.

[a64pilot]

Is it possible that your original thermostat had a small hole in the flange, but the replacement one doesn't?

[twinboat]

T stat upside down??

[Dulcesuenos]

Originally Posted by a64pilot

Is it possible that your original thermostat had a small hole in the flange, but the replacement one doesn't?

This made all the difference in our last mono's westerbeke. Oe had hole aftr mkt did not, we drilled a small 1/16"? Or so hole in it and no more getting warm under power up. Have you checled the impeller on the raw water pump? One can look good but still underperform just enough.

If your in warm waters I dont think the tstat will be a big deal.

[DeepFrz]

You mentioned the heat exchanger but not the water injection exhaust elbow. Have you checked it to make sure the holes aren't plugged up?

[Lyn Hancox]

Hi all


Thanks got the responses, raw water side is good, plenty coming through, new impeller installed a couple of months ago. Have not checked the exhaust injection elbow though. Will have a look at that today, is it difficult to remove or replace? Presumably I will need new gaskets?

[a64pilot]

Take one of those three thermostats and drill a 1/8" hole in the flange and see if your problem goes away. It has to do with being able to bleed all air out of the system more than anything.

[jstevens]

Lyn,
My guess is you have the former Whoosh (Whoosh). Have you contacted Jack about this problem?

A common source of overheating when the raw water flow is good and the thermostat has been eliminated is the heat exchanger. I had that problem with the original W60 on my P424. It required a thorough cleaning.

Another possibility is an air lock in the coolant hoses going to the hot water tank. That will normally result in an over temp alarm condition. Eliminating the thermostat might cover up the problem, but not fix anything.
My solution to the airlock problem was to disconnect the water heater hoses from the engine and pour coolant into one hose until it flowed out of the other end and then reconnect the hoses to the engine.

John