Calorifier conundrum

[jrudge]

Can you use an auto bleeding valve as used on heating systems ( and I am sure i have seen them in engine rooms also

https://www.bes.co.uk/robocal-autom...17842?ref=gs&gclid=CNmpuvng9NMCFVEz0wodGlcJcw

They take heat and the pressure will be little different to a heating system

 

[Plum]

Further update,

All above suggestions checked. No taps, no inline thermostats etc.

Coolant flows out of calorifier connections when hose removed so no internal blockage.

Today calorifier hose connection at pump removed and an 18" section of clear pipe substituted. Coolant flows into pipe up to level in header tank. However when engine started and run up there is no change in the coolant level in the pipe, so no pressure generated to create flow in the calorifier. This was tried at both connections with the same result.

Conclusion, could the coolant pump be faulty and not pumping? There is no evidence of any play in the pump bearings, nor coolant leakage from the front of the pump. Only possible cause of failure would be the impeller being detached from the shaft? In that case I would expect that the engine would overheat even at low speeds after an hour or two?

Any suggestions to solve the mystery very welcome.

Oh dear. How frustrating. The engine will overheat if no coolant pump. As has already been said, the engine coolant pump delivers very little pressure, it is only a "circulation " device so checking a "head" of water will be difficult. If you connect that clear piece of hose in a loop diectly from the in to the out, can you see any flow? You may have to wait for the engine thermostats to open.

Www.solocoastalsailjng.co.ul

 

[Leighb]

Thanks everyone for various suggestions. Thought I should update you all.

This week we took her out for a couple of full days on the water, and in the course of the first day had a few short runs at higher RPM in the "Waterski Area" in the Orwell. Following this we found we had piping hot water from the calorifier. Today again hot water after running for an hour or two.

It seems that the higher speed may have cleared the problem, and it seems to me that it can only have been an airlock that has now cleared? Hopefully once the airlock has gone it shouldn't come back unless the system is drained again?

Anyway there is no need for any further intervention which is a relief.

 

[longjohnsilver]

Good news, and a none expensive solution, unusual in the boating world!

 

[essexboy]

Interesting to see if you get hot water at river speeds now, if it really was an airlock the coolant level would have dropped
wouldnt it ?

 

[alb40]

These engines run very cool at river speeds, in a friends boat with the same engine there is barely any heat provided to the calorifer unless running harder. There's probably nothing wrong other than the engines just aren't making enough waste heat at low revs (under 1500 rpm)

 

[superheat6k]

Thanks everyone for various suggestions. Thought I should update you all.

This week we took her out for a couple of full days on the water, and in the course of the first day had a few short runs at higher RPM in the "Waterski Area" in the Orwell. Following this we found we had piping hot water from the calorifier. Today again hot water after running for an hour or two.

It seems that the higher speed may have cleared the problem, and it seems to me that it can only have been an airlock that has now cleared? Hopefully once the airlock has gone it shouldn't come back unless the system is drained again?

Anyway there is no need for any further intervention which is a relief.

Is your calorifier mounted below the header tank level, including the hoses to and from. If not then it could air lock again until the next higher power run. Also are there any high up bends in the hoses - these need to be as level as possible, or drooping downward from both engine and calorifier. At low engine speeds the momentum / lift from the pump is very low. Larger bore connecting pipes might improve circulation, but as said already it is possible the engine just isn't producing very much waste heat at low power.

 

[Leighb]

Thanks for further suggestions.
I have not tried it on a purely low speed trip. Will do soon.
The Port engine temp never gets above 75C compared to Stb at around 80 to 85.
However it reaches 70 quite quickly.
Yes the header tank has been raised and is now well above the calorifier also a rather convoluted hose run with a bit of a kink fitted by the yard has been routed more smoothly. This latter may be what finally enabled free circulation.
I will try a low speed trip later in the week and see if the water heats up OK.