Volvo D4.260 coolant overflows

[Nigbb]

Hi, does anyone have any ideas on this, one of my D4.260 making coolant!
Let me explain, I used the boat Friday, out for 3hour at least with no problems, was going out yesterday also so did my daily check, all good. I started the engines and they were at idle for 15 mins then decided it was a bit late in the day and we wouldn't go out so shut off engines. Later that night I opened the hatch and noticed green coolant in the bilge and assumed I have a leak however it now seems a bit more complicated.
This is the engine that heats the water system and by coincidence that started tripping the AC breaker last night totally out of the blue which made me ask myself if these two things are connected. There're shut off valves on the pipes that go from the engine to the hot water tank and with these open and the coolant pressure cap off the coolant level raises and overflows at a fast drip.
I have attached a couple of pics, does anyone have any experience of this problem, iam guessing there is a simple hot coil in the tank that heats the fresh boat water and the two, along with the AC elements are all getting together in some way.
Any ideas woul be most welcome.
Thanks Nigel

 

[QBhoy]

Does it do the same if you turn the domestic water pump off and open the taps to vent and remaining pressure ? That’s what I’d try. That would tell you if your domestic pressurised water system is passing into your engine cooling system that runs through the coil inside your hot water tank.

 

[Nigbb]

Hi thanks for coming back to me, that's exactly what I came up with and indeed when I relieved the pressure in the domestic water system the coolant does level does not rise which lead me to conclude that the coil in the heater/calorifier has failed. I presume also that if the engine was running I would be getting coolant finding it's way into the domestic hot system. Would you concer with my analysis that I need to fit a new calorifier/heater?

 

[Plum]

Hi, does anyone have any ideas on this, one of my D4.260 making coolant!
Let me explain, I used the boat Friday, out for 3hour at least with no problems, was going out yesterday also so did my daily check, all good. I started the engines and they were at idle for 15 mins then decided it was a bit late in the day and we wouldn't go out so shut off engines. Later that night I opened the hatch and noticed green coolant in the bilge and assumed I have a leak however it now seems a bit more complicated.
This is the engine that heats the water system and by coincidence that started tripping the AC breaker last night totally out of the blue which made me ask myself if these two things are connected. There're shut off valves on the pipes that go from the engine to the hot water tank and with these open and the coolant pressure cap off the coolant level raises and overflows at a fast drip.
I have attached a couple of pics, does anyone have any experience of this problem, iam guessing there is a simple hot coil in the tank that heats the fresh boat water and the two, along with the AC elements are all getting together in some way.
Any ideas woul be most welcome.
Thanks Nigel

I recommend making or buying a coolant pressure tester. Pressurise and compare pressure drop with the calorifier valves open then closed. With both open turn off your domestic pump and open one hot tap, pressurise the coolant, if anything comes out the tap you will know the pressure from the coolant is leaking into your domestic water. While the domestic pump is on the pressure from that is likely to higher than coolant pressure. Before you buy a new calorifier these tests will ensure that is the culprit. A coolant pressure tester will be a good investment for diagnosing future problems.

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