air lock in calorifer heating circuit

[homer]

It seems I might have an air lock in the calorifier heating circuit. Recently, I drained the primary cooling system in order to fit new hoses and I now find that the calorifier is not getting very hot when the engine has been running for several hours. Also, I cracked a joint at the calorifier end of the circuit (without the engine running) and no coolant was visible. There does not appear to be a bleed point so I am wondering if anyone has any tips on how to sort it - without making a mess!

 

[RichardS]

If you can easily access the input to the calorifier, normally the lowest hose, you could crack the joint when the engine is running and see if that flushes out the air.

Other ideas I've used in the past are squeezing by hand and releasing to give a pumping action on any large (30+mm) softer-walled hoses you have in the heating system or, if you have only smaller harder hoses, clamping one of the hoses with a c-clamp or mole grips (with shielding on the teeth) which will direct the full circulation through the calorifier for a short time whilst the engine is still cold but running. You will need to trace the flow route to clamp the right hose run.

Richard

 

[Plum]

It seems I might have an air lock in the calorifier heating circuit. Recently, I drained the primary cooling system in order to fit new hoses and I now find that the calorifier is not getting very hot when the engine has been running for several hours. Also, I cracked a joint at the calorifier end of the circuit (without the engine running) and no coolant was visible. There does not appear to be a bleed point so I am wondering if anyone has any tips on how to sort it - without making a mess!

If the engine coolant hose rises up to the calorifier then back down again on the return there is a good chance of an airlock. Suggest you fit a bleed valve at the highest point at the calorifier with a short length of hose from the bleed valve that you can poke into a container for bleeding. Once fitted you can easily bleed in the future. Bleed when the engine is hot and the coolant under pressure. Open the valve very carefully, don't scald yourself, until the air is out and coolant just start to escape. Close instantly. Job done. Just did mine yesterday after putting in fresh coolant/antifreese. Bleeding when cold will only work if the engine or header tamk is significantly higher than the calorifier to create a head of liquid to force the air out.

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