On my Black Top Zetec, I had a leak around the seam of the plastic expansion tank.
Coolant was evaporating off and escaping through the seam.
Almost impossible to notice!
By replacing the tank, it was cured.
The tank on mine was a Ford part, with the part number only visible once the tank was inverted.
On initial enquiry, my local Morgan dealer, Rutters and MMC we’re out of stock.
The local Ford dealer obtained the part in 4 hours!
So is your plastic "expansion tank" a pressurised tank with a pressure cap or just an overflow tank where the pressure cap is actually at the radiator end.
My Silvertop is a pressurised expansion tank and I replaced the old black metal original with one of Simon's (Sifab) aluminium jobs when I replaced the radiator.
I wonder if the Black Top Zetec is plumbed the same as the Silver Top?
