Expansion in closed circulation engine cooling

[Graham_Wright]

My 1.5 ltr BMC engine is fitted with an indirect Polar cooling system. Is there hidden expansion capability in this or should an expansion tank be fitted?

While the cognoscenti are considering this, where is the best place to tap into the closed circuit for calorifier heating? I had thought straight from the thermostat housing but the consequent run is lousy.

 

[maxi77]

My 1.5 ltr BMC engine is fitted with an indirect Polar cooling system. Is there hidden expansion capability in this or should an expansion tank be fitted?

While the cognoscenti are considering this, where is the best place to tap into the closed circuit for calorifier heating? I had thought straight from the thermostat housing but the consequent run is lousy.

ASAP supply a replacement waterpump - thermostat hose with a 1/2 inch tee and a threaded hose tail that replaces a plug at the rear port side of the head. connect your calorifier hoses to these.

 

[Jcorstorphine]

I never had one.

I converted a BMC 1.5 diesel which came out of a van back in 1980 with a Bowman heat exchanger (similar to the Polar design) and never fitted an expansion tank. Saw the boat this year and the engine is still going strong.

 

[PCUK]

My 1.5 has a car expansion tank connected to the overflow on the radiator cap fitting.

 

[Graham_Wright]

I maybe wrong but as I understand it the Polar system is a keel cooler, so it depends on what other parts are fitted around the exhaust manifold and what the capacity is as to wether there is room for expansion without a separate expansion tank, without more information its not possible to make a call - BUT clearly the engine has been working for a while apparently without one.

No, it's not a keel cooler. There is a heat exchanger which replaces the exhaust manifold and which is cooled by raw water from a separate Jabsco.

Maxi77 seems to have answered my question. Now I play hunt the plug!

Thanks all.