Saw your note---->
>
>However, I can still (as in before the overheating) smell coolant in the 
>passenger compartment.
>
>I do not think it comes from the rear heater.  That used to leak but is 
>repaired and shows no signs at all of leakage.
>
I once had a leak in the rear heater of my 86 Vanagon and the coolant worked
its way throughout the entire rear compartment.  I took everything out,
scrubbed the carpet, tried to wash the cork insulation with a light
detergent solution and let dry in the sun but a light coolant odor lingered
every time I ran the rear heater for several years.  I think once it gets
into the cork insulation pads, its almost impossible to remove
completely..but its probably harmless.

I think the simplest check for "hidden" coolant leaks is to fill the
overflow exactly to the full line when the engine is overnight cool.  My
experience is that even minor leaks result in a coolant drop below the full
line within a few days.   

                                             John Foster
JOHN L FOSTER
DEPARTMENT OF POLIICAL SCIENCE
SOUTHERN ILLINOIS UNIVERSITY
CARBONDALE, IL 62901-4501

Tel:  (618) 453-3172 (office)
      (618) 549-7760 (home)
fax:  (618) 453-3253
Email: jlfoster@siu.edu