[Vwdiesel] Coolant flow through stock oil cooler/heat exchanger

[Sandy Cameron]

At 01:47 PM 16/11/04 EST, you wrote:
.  
>After looking at the system and attempting to draw a coolant flow diagram, it 
>seems that the only flow through the oil cooler/heat exchanger is by
thermosiphon 
>when thermostat is closed (therefore doing nothing to warm cold oil-actually 
>a detriment), and either hottest coolant flowing through "cooler" or 
>thermosiphon after thermostat is open.  Can this be correct. 

Not quite. The water pump is arranged so when the thermostat is closed, it
is pumping coolant throught the block, head, heater core, and bypass, full bore.
Hence the only reason the heater works in winter (and it sure does)
Further, if you ever have a plugged rad or stuck thermostat, the heater core
with full vent fan, is enough to get you home without a boilover. I've done it.

The thermostat operates TWO valves, the obvious one that opens the radiator
return passage into the pump,, and the extra disk on the other end that
closes the bypass at the same time.

Sandy