Thanks a lot for the responses of my posting regarding my overheating westy.
I was off 5 days for the long weekend and just came back this morning.

During the long weekend. I decided to take a serious look at my westy. I 
renmoved the intake manifold and a rocker shaft from one cylinder head so
that all head bolts (nuts) were exposed. I quickly found out that they are
kind of frozen when I tried to retorque them. I decided that hey are tight
enough that retorque will not fix the problem. I discarded the idea of 
retorquing.

As many pointed out that I should take the heads apart, have them resurfaced
and reinstalled with new gaskets/seals. I'll talk to my local VW dealer to see
if I can have them do it for me free since my westy has only 60k miles.

Besides overheating, the westy is also suffering low power. Comparing to my
84 vanagon, it is indeed very poor in terms of engine power. My 84 vanagon
has logged 10k miles and I can push it up to 80+mph, briefly of course, still. 
The westy seems refuse to go above 70mph.

I am wondering what went wrong in addition to overheating. I have sawpped all
fuel injection components between the 84 and the 83. Looks to me the engine is
the problem. I think I need to overhaul the engine soon.

Thanks again for all responses.

David Kao