Once again - VR fan controller :)

[Dutch24V 0]

Can we have a poll or something to see how many VR's after-run the aux. water pump REGARDLESS of engine temp., and how many don't?

 

There are so many conflicting stories and I would like to find out the truth about these damn things before I go and splash 130 euro's on one that still won't after-run the aux pump when the engine is cold.

 

From what I can figure, having read numerous posts, the Bently Bible and the Pete Russex book the fan controller should NOT run the aux water pump on shut down when the engine temp is below 85 degrees C. I would like to know if this is 100% true or not as some people have stated that when they purchased a new one it did after-run the aux water pump even if the engine was cold. This makes sense to me, but apparently the *official* literature implies that it shouldn't do this.

 

Dutch

[Dutch24V 0]

Anyone :?

[dr_mat 0]

I *think* it only runs with the fans during after-run. But I didn't sit there and watch ...

[emirc 0]

From what I can figure, having read numerous posts, the Bently Bible and the Pete Russex book the fan controller should NOT run the aux water pump on shut down when the engine temp is below 85 degrees C.

Dutch

 

Mine behaves exactly like this. Aux pump should run only with fans afterrun. Therefore, there is no logic for fans running while engine temperature is below 85

[craigowl 0]

Yes, I hear mine (newish) starting up with whirring and gurgling noises when ignition is switched on but engine not started.

[Dutch24V 0]

Yes, I hear mine (newish) starting up with whirring and gurgling noises when ignition is switched on but engine not started.

 

Even if the engine is cold and without the fans coming on too?

 

Dutch

[craigowl 0]

Thought you would ask that, Dutch! :lol:

 

I know for sure it does it when you switch engine off after a run and then turn ignition back on.

Will try cold in a minute. 8)

[craigowl 0]

Cold engine - ambient air temperature 11C. Cloudy/dull.

 

Turning on ignition I could hear gurgle then whirring as auxiliary pump got going. Listened for about half a minute with ignition turned on and it kept running. No fans came on. which is what I would have expected.

 

This thread re replacing kaput aux pump. viewtopic.php?f=1&t=46362&hilit=auxiliary+pump+Bosch

[Dutch24V 0]

:) Thanks for checking Craigowl.

 

..but, does it carry on running when you turn the ignition off with a Cold engine, ambient air temperature 11C & Cloudy/dull? :)

 

Mine runs all the time when the ignition is on, hot or cold, but when I switch the engine off it only runs with the cooling fans whent he temp. is above +/- 80 ?

 

Dutch

[dr_mat 0]

Then it is working perfectly. Move on with your life ....!

[craigowl 0]

Yep - what dr_mat says is what happens, I believe.

It does not carry on running when you switch cold engine off.

 

I read somewhere that it keeps running when you switch off hot engine so that excessively hot spots in upper part of engine around cylinder head can be cooled down a bit, thus preventing head warping. Seems reasonable, as you will notice the relatively large engine block takes several hours to cool down after a good run.

[Dutch24V 0]

I would like to, but this quote is stopping me:

 

"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."

 

:?

 

Dutch

[Dutch24V 0]

...I also remember my fans used to run for a longer period before. They would run on when engine was hot, then stop after the temp. went down enough, but then would start again 20-30 seconds later. This would repeat until the whole system was cool enough for them not to run on again.

 

The only way this could have happened is if the aux. pump continued to circulate the coolant after the fans had stopped, as the heat being absorbed from the exhasut manifold would have warmed the circulating coolant enough to trigger the fans again. If the coolant stops circulating once the fans go off after the first over-run cycle, the coolant around the temp sender will not heat up again to run them for another cycle?

 

Dutch

[craigowl 0]

I am almost certain mine does not go into a "10 minute afterrun program" regardless of temperature.

 

What you say about the stopping and restarting of the fans after a hot run fits in well with the intended behaviour of the system, if I am following everything.

 

IMO the aux pump is performing forced circulation to a cooling system that is still being locally overheated where in contact with the hottest parts of the engine and where being chilled by the fan(s) forcing ambient air through the radiator.

 

I suppose if things were left as they are after a hot run - with no aux pump and no fans - the system would only very slowly cool down, leaving local, potentially warping, very hot spots at the top of the engine with the cooler liquid at the bottom.

 

This would completely repress the engine being cooled by convection within the cooling system, hence the need to forcibly circulate the coolant until its temperature is generally below 80C, or whatever, when the danger of greatly overheated spots has passed.

[Dutch24V 0]

Precisely craigowl, but it's still not clear if this is how it is meant to function or not :(

 

That quote was from Mr. Cheeswire btw.

Kev, are you sure your pump has a 10 minute run-on after engine shutdown with a cold engine?? ...and once your fans stop after the first over-run cycle does your pump keep on circulating coolant for 10 minutes?

 

If not then I guess all is well and the functioning most seem to have is correct. If so the mystery deepens :)

 

Dutch

[ReekieVR 0]

My fans run on as they are supposed to after a blast.

I dont think the aux pump ever does without ign on.

 

I do have a hot start problem.

 

I have shredded my brain trying to figure all this out before, so presume its the fuel pump now ( which i dont intend to replace just to see if it helps )

[Toad 0]

I've looked at them a bit and I've come to the conclusion that some (early vrs possibly) after-run for 10 minutes no matter what. Others (Late??) only after-run with the fans. The pump runs constantly with the ignition on.

 

The cars that I have seen with the three fuses in the fan/aux pump controller seem to only after-run with the fan.

 

If the pump is not running at all, take the contoller pack off and shake it, if there is a rattle, one or both of the diodes inside have gotten too hot and unsoldered themselves from the pcb. You can open it up and resolder them if necessary.

 

I have a particularly noisy pump, so I've been able to hear where and when it runs clearly.

[Dutch24V 0]

Thanks guys.Getting closer to an answer I think.

 

I think what you've observed is correct Mr. Toad, as I know there are 2 controllers - 1 with a 4 & 8 pin connecter and 1 large fuse, and the other with a 4 & 10 pin connector and with 3 fuses. My dealer also asked which one I needed so had to give him the part number of the one I have. Mines the later one with 3 fuses and a 1 and 10 pin connector btw.

 

I've bitten the bullet and ordered one just to see if it makes a difference :)

 

It would seem strange that VW removed the after-run when cold from the later model as I would have thought it would be safer to run the coolant without the fan for the reasons explained in my previous but one post and Craigowl.

 

Dutch

[plateletboy 0]

mine only runs with ignition on, and after runs only when hot with fans on....

 

I've looked into this also and found reference on US forums of 2 types of controllers. one does the 10 min over run, one doesn't....

[Dutch24V 0]

There are definately 2 types of controllers for Europe too, and I'm fairly sure for the UK also. I guess they are the same 2 as the Americans refer to, so one must over-run when cold and one not.

 

I just don't understand why VW would want to remove that particular feature on the new one though :?

 

I'm not sure if you can switch a late one for an early one either without at least hacking the loom to the 10 pin connector on the controller.

 

Dutch

[craigowl 0]

Two advantages of not having the 10-minute run on when "cold" are:

 

1 - Pump runs a lot less time, hence less wear. (Some of us are probably in agreement that the pump appears to fail too easily and needs all the rest it can get!)

 

2 - Less drain on battery. (Some of us know of the unacceptable voltage drop on the battery for some, as yet unfathomable, reason from the time the engine & hence alternator stop, such that after about 10-20 days the engine cannot be started.)

 

Call me cynical, but it would not surprise me if VAG resorted to sacrificing the 10-minute "cold" running aux pump facility to try and improve the pump wear and battery drain. (Why do expensive surgery if you can bluff your way out of it using an Elastoplast?)

The "fix" don't work, anyway. :lol:

[Dutch24V 0]

Fair points craigowl,

 

but it should still at least run whilst the engine coolant is above 80 degrees and the first after-run fan cycle has stopped, IMO of course :)

 

Dutch

[mattkh 0]

Thanks guys.Getting closer to an answer I think. Mines the later one with 3 fuses and a 1 and 10 pin connector btw.Dutch

Hi

Is it possible to put up a picture please. Cheers

[oxfordpaul 0]

I recently bought and installed a new aux pump and fan controller (the later type) and my aux pump works as described above, i.e. when ign on and when after run fans on. The reason for the new controller was to solve the fans not cutting in till 105 but that mystery remains unsolved - I've had new stat and thermoswitch too but have decided to get the switch changed under VW warranty as there's nothing elese that affects the temp at which the fans come I am told?

[Dutch24V 0]

mattkh, It's the same as craigowls:

download/file.php?id=45136&mode=view

 

oxfordpaul, the fans operating temp is triggered by both the themoswitch on the radiator and the yellow temp. sender/switch.

 

Dutch