Replacing auxiliary water pump on VR6.

[craigowl]

I replaced auxiliary (electric) water pump on VR6 a couple of days ago. Pics 1 and 2.

Pump price to nearest £, including VAT:
Quote from VAG Advantage, Stirling – £93, but, when asked, he kindly offered about 10% discount if you can produce CCGB card.

Bought from ECP (Edinburgh) - £68 including CCGB discount on showing card. – identical to original Bosch unit.


After installing new pump, I took old one apart - it was seized - both the impeller and the electric motor.

You will possibly not know it is seized, because, from my experience, the car still runs OK and I had no overheating or coolant loss problems. Consequently, I would recommend those with VR6s check the pump’s 5 amp fuse, you will mostly not know if it has failed, except by visually examining it. (see pic 3)

CAUTION - BE SURE THE RADIATOR FAN IS DISCONNECTED FROM THE POWER WHEN DOING THE FOLLOWING, IN CASE YOU MAKE A MISTAKE - IT STARTS SUDDENLY AND YOU DO NOT WANT YOUR BITS CAUGHT UP IN IT.

Tested in isolation, a new pump does make a slight running noise but if fans are on they drown it out.

I found you can listen to the aux pump in isolation by disconnecting the power supply plug to the (Bosch) radiator fan and linking the two appropriate terminals on the yellow coolant temperature sender (pic 4) as described in both the Bentley and the Peter Russek books. (I used a small U-shaped staple to bridge the brown wire’s terminal and the one diagonally across from it, i.e. the two terminals you are told to bridge in the books.)

By the way, I found there is no need to drain all the coolant from, say, the bottom hose connection (really awkward for me) or the “official� drain plug (can crumble, I believe!)- I merely drained coolant from a very accessible hose half way up the engine. (see pics 5(i) and 5(ii))

Final pic (6) shows the extension I fitted to a cordless power drill (9.6v) to retighten the hose clips after refitting the two hoses to the new pump and the one from which I had drained about half of the coolant. After a lot of frustration, I found this to be a far easier task using this arrangement, compared to trying to screw up the hoses using an ordinary screwdriver. Wish I had thought of it years ago. I used a torque setting of 2, cautiously followed by 3.

[Kevin Bacon]

Nice one!

You can buy long flexi drivers with 6, 7 and 8mm hex ends for hard to reach jubilee clips , but I like the drill idea, any excuse to use one

RE listening to the pump. All you need to do is turn the ignition on and off and it'll go into it's 10 minute after run program (regardless of coolant temp) and you should then hear the pump buzzing away without the fans intruding. It's quite a loud buzz, even on new ones.

You're right though, you won't notice when it's dead when driving, but the engine will take a lot longer to cool down when switched off on the after run program.

[craigowl]

kevhaywire wrote:

RE listening to the pump. All you need to do is turn the ignition on and off and it'll go into it's 10 minute after run program (regardless of coolant temp) and you should then hear the pump buzzing away without the fans intruding. It's quite a loud buzz, even on new ones.

Yep - I had seen that somewhere, but when I tested my old pump that way I still was not sure if it really was dead and was perhaps failing to start that way due to some other (electrical) quirk.
Before I took a chance and shelled out my £68 for the new pump I eventually became 95% certain that the old one was busted after testing it using a straight 12v from the battery.

[dinkus]

I replaced mine last week, just before the big Germany road trip. The old one that came out was still working, but made a horrible grindy "I've got lots of broken bits of plastic in" type noise

The new one does make a quiet whirr, but nothing you can hear once the engine's running.

FYI if you put the ignition on all the way (bar starting the engine) then the aux pump comes on and you'll hear it whirring

Nice writeup though - I'll have to wikify this at some point

[Jim]

Ah yes - Doms aux pump change came complete with lots of cursing as he'd just arrived and the system was still nice and hot

Could really hear the difference though as he said - new one was so much quieter compared to the old grindy one!

[ReekieVR]

Just about to do this job craigowl. Your timing is impeckable !

Thanks for some very usefull info. Hopefully this will cure my hot start problem as i am sure there is no run-on taking place ( indeed after reading this thread - there may not be any aux pump action at all ! )