Originally Posted by Graplr

I just put a working aux water pump in my 84. After driving part of the winter without it I notice a vast difference in heating performance. I have a thermometer in my vent. Before I had the water pump in there it would rarely get over 80F at the vent and it would take a good 10+ mins at freeway speeds to get there. Now, as soon as my engine is above 40C it starts blowing warm air at 60F+ and by the time the engine is up to temp it is blowing 90-100F air.

One thing I did differently though is I wired the aux pump independant of the CCU system. I turn it on as soon as I get in the car and let it run. I have it fused and relayed from the battery. My motivation for this was to help with circulation for my Webasto. Note- All of the above observations are from cold starts with out the Webasto on.

So in my opinion, the aux pump does play a large role in heating the interior of the vehicle.