No Hot Water

[Lennie]

After motoring we always have hot water for a shower and cleaning up. We had none at all after motoring for over an hour. The engine temp is normal and I found no obstruction in the water tank exchanger. I plumbed in a bypass before the water heater years ago because it did overheat without it.
Do I have a fresh water pump problem? Pumping enough to keep the engine cool but not enough pressure for the smaller lines in the tank? And last but not least how do you test a water pump?
The engine is a 1981 Westerbeke W40.


Len

[djmarchand]

Len:

After motoring for 15 minutes to get the engine up to operating temperature, feel the hose in and out of your potable water heater and the bypass hose. I suspect that the bypass will be hot and the water heater hose will be cold. Maybe you have built up enough scale in the water heater to increase the pressure drop so that not enough engine jacket water is flowing through it. Either clean the heater or block the bypass.

If all of the hoses are cold, then I suspect that an air lock has developed. Open the coolant fill cap and run the engine for a while. It will often clear up. Worst case pull off the return hose from the heater to the engine, block the inlet to the engine, and put the hose in the fill opening while running until you get good flow.

It is extremely doubtful that your jacket water circulating pump is worn to the point that it won't build up enough pressure. But the only way to know is to pull it off and look at it.

David

[Lennie]

Thanks! I will give it a shot.

Len

[cabo_sailor]

I had a similar problem on a Westerbeke 46. It turns out there is a diverter to channel water to the water heater. It's just a piece of sheet metal within cast iron tube located below the anti-freeze reservoir. Mine broke. If this is your problem, order several (they're cheap) because they are rather brittle. I had to use a dremel tool to shape it so it would fit.

An engine parts diagram should show you if you have such a diverter.

Rich

[cabo_sailor]

Len,

I just looked at the parts list for your W40 and my W46 and it appears that your engine does NOT have the flow diverter that I have. In the W46 parts diagram it is listed under cooling system flow diverter part # 57. Under the W40 cooling system I see no such part. Perhaps it exists but I didn't see anything listed that even remotely resembled that part. Perhaps if you contact Westerbeke they might be able to identify the similar part for your engine, if it exists.

Sorry about that,
Rich

[Capt.Alex]

Is it possible there was no fresh water in the heater while you were motoring? If your system was run down to empty at some point before the cruise and you never opened a hot water tap until after you ran the engine, then there may have been no water in the tank to heat, just a big air bubble...did the faucet/shower sputter out a bunch of air when the hot side was first opened?

[Lennie]

No not out of water, all works fine at the dock with shore power. The hoses are hot through the bypass but the hoses to the heater are cold. I ran water through the exchanger and had good flow.

Thanks for the ideas

Len

[Lennie]

Ran the engine for about 40 minutes after pulling the hose off the output of the water heater and added more antifreeze. Also opened up the cap to the fill tank. Results, no change. Engine temp is normal but not hot water??
What next?

Len

[sailorchic34]

Your thermal bypass is letting all the the water through. So either replace the thermal unit in the bypass if it has one, add a ball valve on the bypass and close it 1/2 way (You'll need to play with it a bit) or remove the bypass.

[Bruce B]

I've got a similar issue with a brand new, professionally installed Yanmar 4jh4-hte. Engine runs fine, but when I plumbed the hot water heater into the system - no antifreeze coolant flow to/from the hot water heater -even though the engine temp remains fine. I am assuming an air lock in the hose to/from the water heater & will investigate when next I get to the boat (250 miles from home). Any thoughts??

[YankeePSC34]

Originally Posted by Bruce B

I've got a similar issue with a brand new, professionally installed Yanmar 4jh4-hte. Engine runs fine, but when I plumbed the hot water heater into the system - no antifreeze coolant flow to/from the hot water heater -even though the engine temp remains fine. I am assuming an air lock in the hose to/from the water heater & will investigate when next I get to the boat (250 miles from home). Any thoughts??

There was a discussion about the water heater recently in the Pacific Seacraft threads on the Sailnet forum.

[Cheechako]

If a changed or new install, air locks are quite common unless your water heater is above your engine plumbing.... You can put a 3 way valve in the highest point to get the air out.