I don't think there are any magic bullets for "fixing" the Vanagon cooling 
system. What I've learned, mostly from other listmembers, is the following:

1. Maintain your cooling system. Change coolant annually. Keep an eye on 
coolant level, check condition of hoses, etc. Watch for leaks in auxillary 
heater core.

2. Install a new radiator fan switch with lower turn-on temperatures. 
Listmember Dennis Haynes can supply these for $30 or so if you can't find 
one locally or don't know what to look for. This is an easy "upgrade."

3. Install an oil temp gauge and use it. Give your engine a rest when oil 
temps get too high.

4. Install an external oil cooler. This one is debateable I think. You add 
some potential for catastrophic failure by running 20 feet or so of 
pipe/hose between the engine and oil cooler. This must be a high-quality 
installation, or the risk outweighs the benefits. I think the benefits also 
depend on the climate where you live/drive. Not that important in the Pa  
cific Northwest. Southern California, Florida, or Texas, different story 
altogether.

To summarize, there are a couple of relatively simple and cost effective 
upgrades, the radiator fan switch with lower switch temps and oil temp 
gauge. Most importantly though, is awareness. Your awareness of your engine 
and its various systems. Bob Hoover can say this much more eloquently than 
I...

A couple of specific comments follow.

2) Water passages to and from the radiator from the motor were too small
for their length on early units. I think this list's FAQ archive seems to
suggest they were enlarged on vans after about 1983.

There were no water cooled Vanagons prior to 1983. The only major changes 
to the cooling system happened in the 1986 model year. I don't know if the 
hoses to the radiator were enlarged or not.

3) Both progressively staged control switches for the two stage fan were
specified with values that are either too high or were inappropriately
located, and should be replaced by lower temperature switches or
relocated to the motor or both.  Keeping the radiator within specified
range is NOT an intelligent design goal, keeping the engine within good
safe design range is an intelligent design goal. So these two radiator
mounted sensor locations appear suspiciously like design errors.

This switch can be replaced with one with lower turn-on temps. I'm not sure 
that locating the switch in the radiator instead of the engine is a design 
error. All design decisions are compromises. It would have been easy for VW 
engineers to locate this switch on the engine, but they didn't. I doubt 
that relocating this switch would make much difference in the performance 
of the cooling system.

5) The current inconveniently accessable bleeder valve for the radiator's
top discourages frequent checks.  An extending tube leading to another as
high or higher final valve?  Repositioning the current valve to accept a
through-the-grill removable extention handle?

The inconvenience of accessing the bleeder valve is greatly overshadowed by 
the inconvenience of raising the front of the van by 16" and keeping the 
engine rpm at 2000 while running between the front and rear of the van to 
check the bleeder valve and add coolant to the tank. If your coolant system 
is not leaking, you should only have to bleed it when you change the 
coolant.

-Mark McCulley
'87 syncro Westfalia