Knowledge search....
My daughter has a small, steel hulled, canal boat powered by a 4cyl Kubota marinised diesel.
I am used to tractor cooling systems but find this one visually impenetrable:-)
There is a header water jacket surrounding the exhaust manifold with the usual pressure relief filler cap. From that a flexible pipe takes cooling water to the top of a rectangular tank welded to a steel bulkhead inboard (I think) from the boat hull. A return pipe disappears below the generator and circulating pump. A further pipe connects to the engine block, said to be from the shower. The boat is fitted with a shower and I now think engine coolant is also routed through a heat exchanger for that?
The problem is that, following a coolant pipe leak, the engine overheats. With the filler cap off and engine running there is no apparent circulation, no emulsified oil or visible gas bubbles.
The impeller pump is not noisy or loose. I believe thermostats fail open rather than closed?
Is it likely that an air lock at the shower heat exchanger would prevent circulation? There is a bleed valve on top of the rectangular tank, no air, is there likely to be another at the shower?
Any other ideas?