I've had my 1983 +8 since 1988, it has always blown the coolant out of the expansion tank i.e. I fill the system to the marked level go for a spin and the coolant has gone!
It's happy to run like that all the time, no further loss when I look at the level in the radiator
There are no puddles in the garage. no anti freeze stains in the engine bay or around the expansion tank
I've run it up to temperature in the garage when topped up and the coolant doesn't appear to be lost, level doesn't change and no puddle.
It's had a new engine and radiator (a rebuild not diagnosis by changing parts!) some years ago.
I've changed both radiator and pressure caps (melvyn R suggested a higher pressure one)
The mystery fluid loss was unchanged.
The only constant is the expansion tank itself, but it looks ok with no splits
I assume the coolant is going out through the overflow pipe when driving
Any thoughts welcome
