Volvo Penta MD22 L Coolant leak

[Poppster1954]

Hi Everyone .We have a Volvo Penta MD 22L that is nearly 30 years old. After a few hours running the heat alarm went off. There was no coolant, but no coolant in the bilge.I also turned off the bilge pump, to see if it was getting pumped out. So had to assume it was going out with the raw water. We got back to Mylor (Falmouth) having topped up several times. We took out the cylinder part of the heat exchanger and serviced it and replaced the rubber hose ends. We also replaced the water pump as it was leaking. There was no difference the coolant continued to vanish.
Could it still be the other part of the heat exchanger? the next idea is the cylinder head? There is no water in the oil. Any ideas?

 

[Beneteau381]

Hi Everyone .We have a Volvo Penta MD 22L that is nearly 30 years old. After a few hours running the heat alarm went off. There was no coolant, but no coolant in the bilge.I also turned off the bilge pump, to see if it was getting pumped out. So had to assume it was going out with the raw water. We got back to Mylor (Falmouth) having topped up several times. We took out the cylinder part of the heat exchanger and serviced it and replaced the rubber hose ends. We also replaced the water pump as it was leaking. There was no difference the coolant continued to vanish.
Could it still be the other part of the heat exchanger? the next idea is the cylinder head? There is no water in the oil. Any ideas?

is it going in to the hot water system through the calorifier? Which water pump by the way?

 

[peter gibbs]

is it going in to the hot water system through the calorifier? Which water pump by the way?

Water disappears routinely from this system in older engines. And varyingly ,- sometimes more, or less. Not via the oil system, so via the cooling circulation..So I experience. But setting off the temp warning - not good.
Yes you can start dismantling further, or, try a Radweld type product in the coolant and see what results you get. If you can restrain loss without alarm, over several hours use, you've probably got it under control

 

[Poppster1954]

is it going in to the hot water system through the calorifier? Which water pump by the way?

No it is not going into the calorifier. it is the coolant water pump. Also there is also no pressure in the system. I can take the top of the radiator while running and there is no build of pressure.