Thanks to all who provided advice. Upon checking the rear heater I found no
leaking hoses, but what appears to be a leaking rear heater core. A short
length of copper tubing has provided a temporary 'patch'.

I assume that the only fix is to replace the rear heater core. Any
suggestions on the best place to find this item? I'm guessing it is not
cheap.

Also - the Bently has no text - just a picture of this rear heater unit.
What is the function of the gray valve at the top of the rear heater core?
Is this an emergency shut off? Or some kind of temperature adjustment?

Thanks
Todd
'88 Westy