Radiator coolant

[inca]

Hi I've just completed a service on my 1969 series 2 FHC. When changing the antifreeze I have added exactly 15 ltrs of coolant though the manual sates it has a capacity of 18ltrs. I have taken the car on a few short journeys and topped up via the expansion tank only and not via the radiator head as advised by Haynes manual. Please can I have any advise as to whether I may have air in the system or blockages? Temp gauge readings are fine. Many thanks

[Tom W]

It seems very easy got get airlocks on the S2. Park the car On a slope facing up hill so the radiator is the highest point. Make sure the heater is set to hot too. If you didn’t drain the heater, that could account for the difference in coolant volume. A slightly sludges block or radiator will reduce capacity too.

I normally fill mine from the top of the radiator, then you can see when the radiator is full. Gently squeezing the top hose might expel some airlocks, you’ll be able to see this with the radiator cap off. When I can’t get any more air from the top of the radiator, I fill it right to the brim with coolant, then put the cap on. I then fill the expansion tank to about an inch below the neck.

[inca]

Thanks TOM very helpful. I don't think I drained the heater matrix if there is a separate procedure to do this? For changing the coolant the manual directed me to drain from the two taps one at the bottom of the radiator and other on the side of engine block..

[Tom W]

If the heater was set to cold when you drained the coolant, the tap that controls flow through the matrix would have been closed, so the heater may not drain. It only blocks one side of the circuit, so coolant could still drain from the other side, but there’s no way for air to get in to replace it, so it may not come out.

[inca]

Ok thanks I had the heater control set to hot so would have drained the whole system. I'll try to top up from the radiator head