Auxilliary Water Pump

[Mick & Tracey]

Trying to eliminate an overheating problem. When should the auxilliary water pump on a diesel come on?

[Rusty Red]

It will only run after the engine is switched off to bring the temperature down. Also think it ticks over once or twice on the starter motor when you fire up the engine also, but only to prevent it seizing. D

[Mick & Tracey]

Thanks

[Fully Loaded Cali']

You can test it by removing the wired connector and wiring direct to battery as there is only a positive and a negative. It's a shared part with the T4 2,5TDI, GSF sell them for about £70 or look out on ebay, i got a good second hand one for £15.

However, this will not have any effect on your overheating.

You need to describe your symptons as it could be:

Faulty thermostat - remove it and see if you overheat.
Water pump Kaput
Blocked rad
Expansion cap valve kaput
Head Gasket

List goes on.