Volvo Penta D2-40

Regards,

Maarten-Pieter 

All the best

Paul

As with everything, nothing is clear cut. The original engineers didn’t clean the sea water filter which was almost completely full of bits of mussel shells, which I think they should have seen and made them question a blockage in the sail drive. But then we could have spotted that too, but they were official Volvo Penta agents. 

This caused the engine to overheat, spewing coolant out of the pressure cap. We immediately turned off the engine waited for it too cool, topped up the coolant and used it very sparingly and at very low revs back to the marina. We then had the sail drive cleaned, oil and coolant changed and all seemed ok. Next time we used the engine, low power and black smoke/water was almost immediately obvious in the exhaust, this time all the coolant had disappeared but into the engine. Again we turned off the engine sailed back to the marina entrance and were towed back to our berth. 

The engine is being taken out on Monday for inspection so I will report back after that, but it would seem that these engines are very sensitive to even a small amount of over heating. 

All the best

Paul

That sounds like real bad luck. Whatever the actual fault you should have had an overheat alarm from the Volvo cockpit panel before any serious damage was done. If your alarm didn't sound then that needs investigating as a priority - it could have saved the engine.

The alarm should trigger around 120C, about the time that the pressurized water starts to boil. I know this because mine triggered last summer (2018) when I started the engine without turning the seacock back on. Normally when cruising I leave the seacock on but I had turned it off to clean the raw water filter (full of seaweed strands and small shrimps) and obviously forgot to turn it on again when I'd finished. Silly boy! When the alarm went off (next day) it caused a few seconds panic as we were exiting the cill at Trebeurden and didn't have any sail up or room to anchor! Fortunately no damage was done as the fresh water coolant was only just starting to boil and the exhaust hose and water trap/silencer also seemed to have survived.

I have since fitted a sea water flow alarm that triggers if the engine is started and no cooling water is flowing. This should detect a potential overheat situation long before it becomes a problem. Unfortunately the company making the kit I used has recently ceased trading but Google can suggest several alternatives.

Fingers crossed that your engine can be easily fixed. I'm sure several of us with the D2 series engine will be interested to hear the conclusion to this sad tale.

Regarding the overheating, was there a failure of the cylinder head gasket? If there was it is hard to see it in the photos.

Have your engineers suggested checking the heat exchanger internals? This seems a more likely source of 'crud' (from salt water?) in the waterways than the calorifier (which only contains clear mains water).