Join Date: Sep 2004
Location: Portland Dorset, , United Kingdom
The coolant tank may be full, but take the radiator cap off, I bet the radiator is empty.
If so, check the hose between radiator and header tank and that both ends are air tight especially the push fit into the top of the tank.
The coolant expands when hot, the rad cap valve opens pushing excess coolant to the tank but instead it steams to air. When the engine cools, it draws in air instead of the reserve coolant from the tank.
yes the header tank contents will stay cool
1984 GL1200 Aspencade with 1966 Watsonian Palma sidecar
1984 GL1200 Interstate engine out and awaiting waterpump and frame repair
2012 Royal Enfield 500 EFI Bullet (daily ride)
1998 Reliant Robin LX estate (for when it rains)
1992 Reliant Robin saloon (if the other breaks down!)