[Vwdiesel] More on coolant flow through radiator

[Wade Yorke]

The radiator is just three years old and is new, not a re-core.  A new 
thermostat was installed with the engine less than a year ago.  The 
expansion tank is from a Jetta rather than from the old gas engine.  
The water temperature needle would stay just below the LED with the old 
wasserboxer and with the diesel it runs just above the LED during 
normal driving, but when running fast (a relative term with a 75 hp 
diesel in a 5,000 lb vehicle) on the highway or pulling up a long hill 
the temperature will rise.  I have noticed that the engine and heater 
warm up much more quickly with the diesel than the gas flat four.  This 
I found strange as diesels are not known for fast warmups, especially 
around town.
I believe it is a closed system with the radiator at the highest point 
in the cooling system.  Could the passage ways in the radiator be 
designed to flow coolant better in one direction?  The installation 
instructions cautioned that the hose going to the expansion tank had to 
be reduced so the coolant would be forced to the radiator rather than 
just looping through the expansion tank.  When I looked I found that 
the hose going to the expansion tank was much smaller in diameter than 
the hoses going to the radiator so I did not try to reduce it any 
further.

Thanks for the responses

Wade Yorke
'84 Westy 1.9TD