VR6 Aux Water Pump Question (when should it be running..)

[Jim 2]

Steadily building up a laundry list of jobs to tackle on my car. One of which is the aux water pump which has become quite loud in recent months. However there is a bit of a mystery. I normally disconnect my battery as the car sits in a lock-up for a couple weeks at a time between use.

 

When I first connect the battery, and turn on the ignition for the first time, the aux water pump whirs to life and keeps on whirring. Fine. However if I don't start the car and instead turn off the ignition, and back on again, the pump doesn't come back on again. Is this normal?

 

I was under the impression that if the ignition was on, the pump would be running (and of course if the coolant is at a certain temperature) - no ifs, no buts. So any idea?

 

Thanks.

[g0ldf1ng3r 15]

that is a good question Jim

 

I have never tried the sequence you mention but I can not see any logic in the aux pump only running on the first turn of the key after reconnecting the battery

 

as you say I thought it would always run if ignition is on or if the engine temps tell it to after use & the key is removed

 

I am in the VR today so can not test straight away but I can do so when I swap the cars over when I get home tonight & let you know

 

I have the feeling for needing some decent power on the way to work tomorrow lol

[VAG-hag 0]

I'm sure I get the pump every time I have ignition on.... Will check tonight mate

[Kevin Bacon 5]

I could never get a definitive answer on it either. Maybe you found a secret 'feature' to turn it off Jim! :)

 

I do know that it's function is tied in with the 'yellow' temp sender (now green / black I believe) in terms of operating temp, but it's always just run with the ignition in my experience, but it should shut off after 5 mins or so when the engine isn't running.

[Jim 2]

Hmm.. the plot thickens! Be interested if other folks could see what behaviour they get with their aux pump.. I haven't tried other combinations such as starting the car, then stopping it, then putting the ignition on to see what happens with the pump, nor have I hung around long enough after stopping the car to hear if it remains running as normally when I've put the car away I let the fan run as long as it needs, then pull the battery.

[VW_OwneR_85 2]

i was always under the assumption that it only came on once the engine is off with cooling system at a certain temp , same as the fan...?? because AFAIK its only job is to keep the water circulating to avoid hot spots around the head so it all cools down evenly.

[Dox 23]

Disconnecting the battery will mean the ecu will have to relearn sensor perameters, the pump running could just be part of a safe start up sequence after the battery ahs been disconnected?

[VAG-hag 0]

Hi Jim,

 

I tried mine today. I got aux pump each time I turned on ignition. When hot my fans and pump stay on for one cycle but when the fans go off the whole lot shuts down.

 

Hope this helps somewhat.

[daves16v 1]

Jim, my pump also runs as per Chris.

[Jim 2]

Hmmmm.... time to look into some fault finding in the system then! Thanks guys.

[g0ldf1ng3r 15]

morning jim - mine was as per chris' post also

[Jim 2]

Wonder why it would run sometimes, but not always on mine then. Must be a bad relay or something?

[Jim 2]

Just as a follow up for this, it seems to be nothing more sinister than the pump itself is just goosed.

 

I spent a bit of time today following some steps I was advised to try over email (checking fuses, etc - they were all fine) - one of the steps was to bridge pins 1&3 of the yellow sensor connector which is supposed to bring on the fans and the aux water pump. I tried once to verify the step works, and then disconnected the fans so I could actually hear the aux water pump (and also avoid slicing my fingers!) but sure enough the auxiliary pump did nothing.

 

However I began to wonder if it was just a bit stuck so gave it a tap with a spanner and you could hear it begrudgingly whirring into life. Tapping it more made it occasionally stop and start. Sometimes it would run for a while and then stop. Either way, it's had it.

 

I suppose the only mystery is why it seems to work LOUDLY the first time I put the ignition on, and then pretty much never again without being clouted.. but bottom line is I need a new aux water pump as this one is clearly in it's death throes and there's nothing more complicated it seems with sensors or whatever needing replacing, or bad wiring.

[Kevin Bacon 5]

Try stripping it down and cleaning it first. They get gunked up with junk floating around in the cooling system. All you do is undo the 3 screws holding the 2 halves together, dead easy.

[Jim 2]

Ah good tip - thanks mate. I may do it out of curiosity just to see what state it's in, but have actually ordered a new one now - Bosch one from German eBay for about £40 delivered.