Sludge in Heat Exchange

[Aquarius]

When I removed the cap from the heat exchanger on my Yanmar 2GM20F there was a lot of black sludge inside the cap. There is also some of the same slugde in the expansion tank. The motor has not been run for approximatly 4 years. We still have made no attempt to start the motor at this time. Is this type of build up to be expected, and what kind of recomendation would you suggest to properly flush the system to remove the contaminant?

If this is not to be expected what are some suggestions?

Thanks

 

[Ron McCoy]

Your engine coolant is very bad and has contaminated the heat exchanger. The entire cooling system should be flushed and the heat exchanger removed and cleaned professionally by a qualified boat yard/etc. Starting the engine will result in a quick overheating situation. Running the engine hot will soon destroy it. You should have the engine checked by a qualified marine engine mechanic, as other critical parts may damaged by starting the engine. I quess the engine oil hasn't been changed in four years either - just a quess. Also check the condition of the diesel fuel. By all means remove it from the tank as it's well past any acceptable standards. You'll also need to change the fuel filters and clean the tank and fuel lines. I could go on, but hopefully you'll get a mechanic on-board to assess the problem first-hand.

 

[jtm]

if you have a pre-heater (as in water heater) loop from the engine to the hot water heater , then that sludgy stuff may be clogging up the hear exchanger in your house water heater as well. Check that loop by pulling a hose- be wary of hose inventory spills when you do it.

I don't know what engine you have but I wonder if you might be boxing oil with your internal side(antifreeze) cooling system (not the fresh water side) - this can happen with a blown head gasket or if the internal side pump shaft breaks or the shaft bushing separating it from the engine oil lube system goes bad- Check that your internal side pump pulley is tight and snug. On 2GMF its the center top pulley.