Group,  

A simple but hopefully not-too-stupid question.� After years of fairly trouble-free duty by our 85 Westy's cooling system (except for the p-i-t-a annual drain, refill, point-to-the-sky, top-off and repeat process), it is leaking coolant - specifically around the cap of the coolant reservoir.� 

The cap is on tight.  Also, coolant placed in the overflow tank when the engine is cold appears to be getting sucked back up to the reservoir tank.  The overflow tank has been empty, however, when the leak occurs - after the engine temperature has gone past the mid-line of the temperature gauge from extended idling. 

The question: do the reservoir caps simply go bad and the two-way valve in the cap stops directing coolant to the overflow tank behind the license plate?�  

All comments, guesses and opinions are greatly appreciated! 

Todd
Columbus, Ohio
85 Westy (Rivendel)