The early +8 can be a pain to clear airlocks. a lot of hose squeezeing and topping up of the expansion tank. My +8 also had a habit of the spade connection dropping of the fan. Cured this by turning the fan over in its mounting so that the spades connected to the top of the fan.

.+8 Now gone for a 1800 4/4. Duratec in bright yellow.