Coolant loss - Volvo D2 55

[duncan99210]

The “end caps” are, I think, part 2 and 3 on this diagram https://www.marinepartseurope.com/en/volvo-penta-explodedview-7744440-26-9867.aspx .

 

[pandroid]

The D2-55s predecessor, the MD22, is notorious for spilling its coolant, mainly at switch off. That's why most people (including me) fit the expansion tank. The coolant expands into the tank when its running, then retreats back into the engine as it cools. If you don't have it, the coolant loss looks a lot, but doesn't make much difference when you look in the heat exchanger.
The D2-55 is a different engine, but maybe the symptoms are the same.

 

[Bobc]

The D2-55s predecessor, the MD22, is notorious for spilling its coolant, mainly at switch off. That's why most people (including me) fit the expansion tank. The coolant expands into the tank when its running, then retreats back into the engine as it cools. If you don't have it, the coolant loss looks a lot, but doesn't make much difference when you look in the heat exchanger.
The D2-55 is a different engine, but maybe the symptoms are the same.

It's still a Volvo though ;-)

 

[dunedin]

The “end caps” are, I think, part 2 and 3 on this diagram https://www.marinepartseurope.com/en/volvo-penta-explodedview-7744440-26-9867.aspx .

Thanks - I guess they must be hidden below some of this stuff then?
Rear view -
Front view -
Not exactly easy access !

 

[dunedin]

So I am still mystified how the coolant level is still high after losing nearly a pint. Should I try to test the coolant water salinity to see if somehow salt water got mixed in?
Best way to do that accurately?

 

[duncan99210]

OP, does the engine have a calorifier connected to it? Our calorifier coil got a small leak in it and produced the symptoms you’re describing: coolant loss in the bulge but no apparent lowering of the level in the engine. Took me a bit to figure it out but once I’d disconnected the pipes to the calorifier , that stopped the problem. Fitting a new calorifier was the end solution.

 

[dunedin]

OP, does the engine have a calorifier connected to it? Our calorifier coil got a small leak in it and produced the symptoms you’re describing: coolant loss in the bulge but no apparent lowering of the level in the engine. Took me a bit to figure it out but once I’d disconnected the pipes to the calorifier , that stopped the problem. Fitting a new calorifier was the end solution.

Interesting. Yes have calorifier, but had forgotten it’s role in things.
The coolant definitely didn’t come directly from the calorifier though, as was in GRP sump under the engine not in the bilge. Is this possible with your failed calorifier scenario?

 

[mikegunn]

OP, does the engine have a calorifier connected to it? Our calorifier coil got a small leak in it and produced the symptoms you’re describing: coolant loss in the bulge but no apparent lowering of the level in the engine. Took me a bit to figure it out but once I’d disconnected the pipes to the calorifier , that stopped the problem. Fitting a new calorifier was the end solution.

I’ve had this happen too, but it only occurred when the boat’s fresh water system was pressurised. The give-away was the fact that pressurising pump would run for a second or two every couple of hours or so. It appeared that when pressurised the fresh water from the domestic tank was under sufficient pressure to create a leakage path, but when the system was not under pressure that of the engine’s cooling system was insufficient to reverse the process. As a result the domestic system remained uncontaminated. Unfortunately the only effective solution was replacement of the calorifier.
Mike