# Aux water pump help



## ikeaaxel (Oct 15, 2014)

I have read that the auxiliary water pump should run for 10 minutes after turning the car off no matter of the temperature.

I couldn't hear mine running so started investigating.

First of all I checked that the electric pump worked by connecting a live 12v feed and sure enough it came to life.

The fuse (16) is fine but when I remove it the radiotor fan starts spinning (only 1 of them which is odd)

What should my next check be. Is there a sensor or a relay which could be broken stopping it getting the 12v feed?

Thanks


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## Hoggy (May 8, 2002)

Hi, With fuse 16 removed both fans should run. The after-run pump gets it's signal fom the fan control module beneath the battery, so that may be involved. If the pump doesn't run the 12v is swtched off after a couple of seconds so not easy to test.
The pump can get filled with crud & not start immediately, but can be removed & striped down. 
Hoggy.


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## ikeaaxel (Oct 15, 2014)

Thanks Hoggy

So I've got 2 problems if one of the fans isnt functioning properly too.

What makes the fans run if I remove the fuse? Would have thought it would be the opposite.

So if the pump works with a live feed does that mean there is something up with the fan control module?


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## ikeaaxel (Oct 15, 2014)

Further to diagnose the problem

The Earth on the plug to the water pump isn't showing any signs of working and I am not getting any power from the live feed.

Have ordered a new fan module so will look into that when it arrives


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## scott18T (Oct 7, 2014)

Watching this thread with intrest,as I have the same problem.

Scott


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## ikeaaxel (Oct 15, 2014)

Received my new fan module yesterday but I've run out of time to check into it any further.

Spoke to my local vag independent specialist and he said not to worry as it isn't necessary if you let the car run a little while after stopping. Most of the time people have them disconnected as they drain the battery so much especially if you do short journeys.

Not so worried about fixing it now


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## scott18T (Oct 7, 2014)

I tryed a spare pump today with no joy, so I must have bad connections at the controller or the controller is duff.


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## scott18T (Oct 7, 2014)

Have got my aux pump running now.
The spare pump I had was stuck, after a clean up and a sharp tap with a mallet, it came back to life.
I then tryed this on the car and it worked correctly, which proved that the wiring and controller were o.k
I then reconected the wiring back to the pump on the car and gave the pump and tap with the mallet, and started working.
Its been working correctly all afternoon, but will keep checking its operation regulary.


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## daytoncarcare (Nov 24, 2018)

I may have to check mine. Already checked main water pump and changed t-stat. The temp will get slightly hot (one notch above middle) when going up a hill or a few hard pulls accelerating. Also if it's very cold outside, which it has been lately, it will get cooler then normal when accelerating hard. I suspect bad coolant flow either from aux pump or radiator. Also both fans come on with AC but not one or two fan when it gets one notch above normal. Fan temp switch on radiator maybe?


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## Hoggy (May 8, 2002)

daytoncarcare said:


> I may have to check mine. Already checked main water pump and changed t-stat. The temp will get slightly hot (one notch above middle) when going up a hill or a few hard pulls accelerating. Also if it's very cold outside, which it has been lately, it will get cooler then normal when accelerating hard. I suspect bad coolant flow either from aux pump or radiator. Also both fans come on with AC but not one or two fan when it gets one notch above normal. Fan temp switch on radiator maybe?


Hi, Aux pump wont affect coolant temp once engine running. If your low/high coolant temps are true, appears to be thermostat. Did you use OEM 87 degree stat Part No. 050121113C ?
Hoggy.


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## David C (Apr 15, 2013)

daytoncarcare said:


> I may have to check mine. Already checked main water pump and changed t-stat. The temp will get slightly hot (one notch above middle) when going up a hill or a few hard pulls accelerating. Also if it's very cold outside, which it has been lately, it will get cooler then normal when accelerating hard. I suspect bad coolant flow either from aux pump or radiator. Also both fans come on with AC but not one or two fan when it gets one notch above normal. Fan temp switch on radiator maybe?


Both fans constantly with the AC or stopping and starting?

Your issue unlikely to be the electric pump or the rad.

Possibly poor thermostat (was it genuine OEM?) or the temperature sensor.


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## daytoncarcare (Nov 24, 2018)

David C said:


> daytoncarcare said:
> 
> 
> > I may have to check mine. Already checked main water pump and changed t-stat. The temp will get slightly hot (one notch above middle) when going up a hill or a few hard pulls accelerating. Also if it's very cold outside, which it has been lately, it will get cooler then normal when accelerating hard. I suspect bad coolant flow either from aux pump or radiator. Also both fans come on with AC but not one or two fan when it gets one notch above normal. Fan temp switch on radiator maybe?
> ...


Fans come on as usual when I turn the AC on, but I noticed that single fan (or dual) don't come on when it gets slightly hotter. I was thinking flow or possibly the sensor on the radiator. Though I had same issue on an older BMW 5 series that would get hotter on hill, replacing the radiator solved that. I thought about upgrading to the Mishimoto MMRAD-GLF-99 Radiator. The rad temp sensor switch is an easier and less costly remedy so will try that first. Tried two t stats and same result and temp sensor on flange is new as well. (sorry had to edit a few times)


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## David C (Apr 15, 2013)

daytoncarcare said:


> David C said:
> 
> 
> > daytoncarcare said:
> ...


It isn't a sensor on the rad, it is a 2-stage thermal switch.
That won't cause it to run cold though, which is one of your issues.
A poor thermostat will though, or a failing temperature sensor sending duff info to the gauge.

Where were your thermostat and sensors from?


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## Hoggy (May 8, 2002)

Hi daytoncarcare Depends what you mean by hotter. 
Check actual coolant temp by using* Code 49 *on climate control. Click link.




Hoggy.


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## daytoncarcare (Nov 24, 2018)

OK well maybe find a parts car and pull a rad' and swap it out as a test. I have no idea how old mine is, I suspect it's original with almost 120k miles on the car. Rads are inexpensive so will go with a new one soon, though wouldn't mind upgrading to an all aluminum one


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## daytoncarcare (Nov 24, 2018)

Hoggy said:


> Hi daytoncarcare Depends what you mean by hotter.
> Check actual coolant temp by using* Code 49 *on climate control. Click link.
> 
> 
> ...


I have a VagPro OBDII reader that gives me live data so will check that against temp on cluster. I know clusters can go bad and also give false reading on the CC display so not an accurate test. Thanks for the info anyways. Here's a vid I made with my 2000 model (have an 03 now)


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## David C (Apr 15, 2013)

daytoncarcare said:


> OK well maybe find a parts car and pull a rad' and swap it out as a test. I have no idea how old mine is, I suspect it's original with almost 120k miles on the car. Rads are inexpensive so will go with a new one soon, though wouldn't mind upgrading to an all aluminum one


But you've a fault with the car running cold.....!!

*Where did you get your new temperature sensor and thermostat from?*


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## Hoggy (May 8, 2002)

daytoncarcare said:


> Hoggy said:
> 
> 
> > Hi daytoncarcare Depends what you mean by hotter.
> ...


Hi, As the OBD 11 is the getting the temp reading from the same sensor can't see why it would be any different, bad cluster or not. 
Hoggy.


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## daytoncarcare (Nov 24, 2018)

Hoggy said:


> daytoncarcare said:
> 
> 
> > Hoggy said:
> ...


Climate control pulls reading from the cluster, so if cluster is bad there will be a incorrect reading on CC. OBD pulls reading from the ECU not cluster. Tested this on my 2000 model. It's a 4 pin so sends a reading to both.


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## daytoncarcare (Nov 24, 2018)

Hoggy said:


> daytoncarcare said:
> 
> 
> > Hoggy said:
> ...


LoL Actually ran across this, with you verifying what I was claiming https://www.ttforum.co.uk/forum/viewtopic.php?t=1662122 Wak replaced his cluster and solved the false reading


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## Hoggy (May 8, 2002)

daytoncarcare said:


> I have a VagPro OBDII reader that gives me live data so will check that against temp on cluster. I know clusters can go bad and also give false reading on the CC display so not an accurate test. Thanks for the info anyways. Here's a vid I made with my 2000 model (have an 03 now)


Hi, As the OBD 11 is the getting the temp reading from the same sensor can't see why it would be any different, bad cluster or not. 
Hoggy. [/quote]

LoL Actually ran across this, with you verifying what I was claiming https://www.ttforum.co.uk/forum/viewtopic.php?t=1662122 Wak replaced his cluster and solved the false reading[/quote]

Hi, I know all about Waks cluster/temp prob, but if cluster is affecting Code 46 reading, then the reading using ODB11 will show the same incorrect reading.
A meat thermometer in reservoir will soon confirm true coolant temp.
Hoggy.


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## David C (Apr 15, 2013)

Many people have chased a non existent problem around for months, spending a lot of money on the way, before finally replacing the dodgy temperature sensor and/or thermostat that they replaced at the start of the adventure...

So, once again!!, you've replaced the temperature sensor and thermostat already, but...: where did you get them from? Were they genuine OEM?

:?:

[smiley=gossip.gif]


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## daytoncarcare (Nov 24, 2018)

David C said:


> Many people have chased a non existent problem around for months, spending a lot of money on the way, before finally replacing the dodgy temperature sensor and/or thermostat that they replaced at the start of the adventure...
> 
> So, once again!!, you've replaced the temperature sensor and thermostat already, but...: where did you get them from? Were they genuine OEM?
> 
> ...


Yes Yes Yes OEM


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## daytoncarcare (Nov 24, 2018)

Hoggy said:


> daytoncarcare said:
> 
> 
> > I have a VagPro OBDII reader that gives me live data so will check that against temp on cluster. I know clusters can go bad and also give false reading on the CC display so not an accurate test. Thanks for the info anyways. Here's a vid I made with my 2000 model (have an 03 now)
> ...


LoL Actually ran across this, with you verifying what I was claiming https://www.ttforum.co.uk/forum/viewtopic.php?t=1662122 Wak replaced his cluster and solved the false reading[/quote]

Hi, I know all about Waks cluster/temp prob, but if cluster is affecting Code 46 reading, then the reading using ODB11 will show the same incorrect reading.
A meat thermometer in reservoir will soon confirm true coolant temp.
Hoggy. [/quote]

Nope I use a IR reader I leave the other one in the kitchen


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## Hoggy (May 8, 2002)

daytoncarcare said:


> Nope I use a IR reader I leave the other one in the kitchen


Hi, Yes same here, I have both as well, not that my TT has required either.
Hoggy.


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## daytoncarcare (Nov 24, 2018)

I'll just throw a new temp switch on the rad and see what happens.. wouldn't hurt to have a new one in there and not an expensive part 8)


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## daytoncarcare (Nov 24, 2018)

daytoncarcare said:


> I'll just throw a new temp switch on the rad and see what happens.. wouldn't hurt to have a new one in there and not an expensive part 8)


Installed a new thermo switch on the radiator and it fixed the problem.


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## NtG (Jan 2, 2018)

Should this aux water pump run everytime that i turn on/off the car or only when the temperature is higher than the one of thermostat? :?


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## Hoggy (May 8, 2002)

napostolidis said:


> Should this aux water pump run everytime that i turn on/off the car or only when the temperature is higher than the one of thermostat? :?


Hi, It should run every time Ign On/Off regardless of temp.
Hoggy.


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## NtG (Jan 2, 2018)

then i need a new pump. checked both Audi genuine and Bosch... EUR 225 vs EUR 50. Is it worthy the "premium" or should i go for Bosch ?


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## Hoggy (May 8, 2002)

Hi, Fit the Bosch, probably the same item.
Have you put 12 volts on the pump to prove it is the pump that has failed?
Hoggy.


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## NtG (Jan 2, 2018)

Hoggy said:


> Have you put 12 volts on the pump to prove it is the pump that has failed?


hmm .. you right i should start the other way round ! Will check it, thank you


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## NtG (Jan 2, 2018)

this aux water pump is the "V51" right ?
here is what i found on Audi handbooks


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## Hoggy (May 8, 2002)

Hi, That is the after-run coolant pump, unplug connector & apply 12 volts to pump, does it run? If not replace the pump, if it does run the problem could be the Fan Control Module which is beneath the battery.
Hoggy.


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## NtG (Jan 2, 2018)

just to be prepared.. how easy it to fit these "spring band clamps" that hold the aux water pump? 
oem code: N90687001


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## Hoggy (May 8, 2002)

Hi, Depends how strong you Thumb & fingers are. Correct tool makes it easy.
Hoggy.


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## NtG (Jan 2, 2018)

Hoggy said:


> Depends how strong you Thumb & fingers are


haha.. ok just had a look. Knipex is very expensive but found a decent one think should be ok, its opening is 50mm.
Regarding N90687001, what exactly the size "27x12" means please?


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## daytoncarcare (Nov 24, 2018)

Professional Hose Clamp Pliers Repair Tool Swivel Flat Band for Removal and Installation of Ring-Type or Flat-Band Hose Clamps
by BaFu $20 on Amazon. The rest I saw were $50 or more


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## tt92103 (Jun 4, 2015)

If the Aux coolant pump is taking too much current, the fan control module will turn it off immediately.
So you could connect 12V to the pump directly from the battery and the pump works, but reconnect it to the fan control module and it might not work. That is the problem I had with my pump... it aged and started taking too much current.


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## imartyn (Aug 31, 2015)

NtG said:


> Hoggy said:
> 
> 
> > Depends how strong you Thumb & fingers are
> ...


I would think 27 x 12 simply means 27mm dia x 12mm wide.


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