Heat Exchanger Coolant Overflow

[TOM]

I'm having a very slight overheating problem which is also effecting the heat exchanger on my engine driven eutectic fridge which gets its cooling water from the motor heat exchanger. The motor is a Brittish Leyland fisherboy an oldie but a reliable goodie .The heat exchanger on the leyland has an overflow pipe which empties into the bilge,I have had to top up the heat exchanger with coolant every trip ,obviously this is not right so i checked for leaks which i found and fixed but the problem still remains,so i got the end of the overflow pipe and stuck it in a bottle and over 2 hours of motoring about 500 to 600 mils half a litre came out of the heat exchanger.
Could any of you Diesel experts tell me if this is normal or do i have a heat exchanger problem .Motor is only running a little hot not enough to set off alarm.

[Badsanta]

Check or replace the pressure cap on the cooling system. Cars and my boat have a collection container that holds the expanding heated water and as the system cools the water is sucked back into the engine. Maybe a good flush of the system. Has there been a change of antifreeze?

[Highlander40]

Tom,
This could be a sign of a failed heat exchanger. This happened to me last year. The overflow tank (you should have one) kept filling up and running into the bilge. The salt water side has greater pressure when the engine is running fast, than the fresh side does. Constantly pushing salt water in and dispacing coolant which runs to the bilge.
Eventually the engine coolant will be all salt water.
A quick test is to check the specific gravity with a common auto antifreeze tester.
The more invasive test it to remove the heat exchanger, boil it out and pressure test.

[HorizonMarine]

When you say top up..... You do leave at least a pint of room for expansion, correct?? If you top it to the top, it will blow a pint or so out as it gets hot and expands.

Or.. you could have a leak in the heat exchanger and the coolant is going out the exhaust. We (who do it for a living) carry a pressure checker with us and would put it in place of radiator cap and see if you are loosing pressure. If not, no leak.

If the coolant is not under the engine, not under the hot water heater, not in the bilge, not mixed with engine oil, its going out the exhaust. Bad heat exchanger. Or... some of them have a gasket between the coolant and salt and maybe leaking there.

gary

[TOM]

Thanks for all your replies .HorizonMarine I have been filling it right to the top so this could be the problem as about a pint is coming out .I will leave it as it is and see what happens . Highlander40 thanks for your responce I'm hopeing you are wrrong as the heat exchanger was replaced in 2004.

[thinwater]

Amalgatech or Southwest Research or others.