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Waddington...
Waddington...

Posted: Fri Jul 11, 2008 6:34pm

Post Subject: Losing coolant water

I'm losing about a pint of water every 4 hours cruising, from a keel-cooled Beta 43 engine. Its not going anywhere in the boat (either engine or cabin bilge), there are no leaks in the calorifier, and the engine and gearbox oil show no signs of water. Exhaust is clear, and the engine still runs sweetly. Where's it going?

Tony-B...
Tony-B...

Posted: Fri Jul 11, 2008 8:51pm

Post Subject: Losing coolant water

To be honest - no idea, it can't, but of course it is. 1. Is the cooling system overflow from the expansion tank or heat exchanger filler neck piped over the side? If so I expect you are filling the system to the brim and not leaving any expansion room for the water when it is heated. As long as I get my finger into the water in the COLD heat-exchanger I would be happy there is sufficient water in the system. 2. You do not mention water in the engine drip tray. See above, perhaps the water is lying under a film of oil. 3. Do we mean keel cooled or tank cooled? If it really is keel cooled you need to pressure test the system in case one of the under boat pipes has started to leak Some are only sealed by a gland nut and "rubber" washer. Do you cruise with the domestic water pump turned off? If so and if you have a calorifier there is a very slight possibility there is a leak inside the calorifier (if you have one). I think you should beg, borrow or hire a cooling system pressure tester and use it to pressurise the system on a HOT engine with the engine stationary to see if you are actually loosing water. However run it up to temperature with the pressure cap OFF. Taking one off a hot engine is likely to get you into hospital with scalds.

Waddington...
Waddington...

Posted: Sat Jul 12, 2008 8:28am

Post Subject: Losing coolant water

There are internal skin tanks on the base plate, either side of the engine drip tray (which is completely dry - I don't let oil or water stay in there). There is an expansion tank which I keep about a quarter full when the engine is cold - any overflow from there would go into the drip tray. The Reeves shell is less than 4 years old, so I can't believe there's a leak in the skin tanks. With antifreeze in the system, wouldn't I detect some in the domestic water if the calorifier was at fault? I put a plate in the way of the exhaust, and didn't find any condensed water forming on it. Someone suggested a small head gasket leak, with the water escaping through the exhaust. Could this have occurred. When the water level first dropped the high temperature alarm went off for about 5 minutes. Still stumped!

Tony-B...
Tony-B...

Posted: Sat Jul 12, 2008 9:06am

Post Subject: Losing coolant water

Now you tell us that you have a skin tank I agree that it is extremely unlikely to leak outside the boat. Did you notice I said "if you cruise with the water pump turned off"? Because if you keep it turned on any leak would normally be from the domestic water into the cooling system. Most calorifiers hold between 6 and 11 gallons and most people do not drink the water from the hot tap,so you may not notice any antifreeze in the hot water, but i emphasise this is a very long shot. Now you tell us that it started with an engine overheat it makes the head gasket thing more likely BUT a simple loss of water is usually via a weep from the head gasket joint. Anywhere else is more likely to get water mixed with the oil or hot gasses into the water causing overheating. You do not mention "running hot" so I assume you are not suffering from overheating. Any water weeping into a dry exhaust is likely to exit the exhaust as steam so may well be undetectable. Water droplets from the exhaust when cold is normally simple condensation from the water vapour created during combustion. If this is ONLY a case of water loss then I doubt you will find the cause until it gets much worse. I would normally suggest that you try to "bring things to a head" by a long fast run upstream on a river, but with horizontal skin tanks which must have doubtful efficiency (hot water rises) I am not sure this is a good idea. If 1/4 pint of water an hour is dripping onto the top of a skin tank it may well evaporate away, but it should leave some kind of residue. I am afraid I really have no idea about what is going on here. You can get a special fluid that allows you to test the cooling system for the presence of hydrocarbons. This often indicates a faulty head gasket. Tony Brooks

Waddington...
Waddington...

Posted: Sat Jul 12, 2008 7:15pm

Post Subject: Losing coolant water

So, its got us all baffled. I've a feeling I'll have to leave it until things come to a head. Thanks for your help anyway, your contributions to the mag are much appreciated.

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