Morris Minor Owners Club

The rad hoses needed replacing... which are now done..I bought some fresh antifreeze/coolant. All went well. Thought I would leave the rad cap off get the engine upto temp to circulate the coolant and let any traped air out.

Well I had the engine running for 20mins at idle .. and in that time I never saw the water flowing past the rad cap..

Is this OK. I have never had any overheat probs.

Is it because the fan is contastly spining so the stat never really gets upto temp to fully open??

Temp gauge in car never went over 75C..

Likely the flow is below the surface - it will be there - at idle it's not that much. Top up and don't worry !

after 20 minutes I'd expect the stat to be open, but if the water's not hot enough then it wont!
When the stat opens you will feel the heat in the top of the radiator - if the rad stays cool, then there's no flow.

An interior heater (when valve is open) will have permanent flow. Often this removes enough engine heat (e.g. in Winter) that the thermostat only opens periodically.

How about: Drive 1 mile (or maybe even 2 in winter) and feel top of rad (should not be hot) drive a few more miles and there should be a noticeable difference.