Auxiliary Water Pump Frustrations

[andrewchapple 0]

Hi,

 

Have searched the forum (and the rest of the web!) but can't find answer so hope you can help.

 

I'm working on a 94/L Corrado VR6 and noticed that the auxiliary water pump doesn't run with the engine off.

 

I ran the checks in the Ultimate Cooling Guide and concluded the fan control module was defective so I swapped one over from a 1995 VR6.

The 1995 car had a replacement FCM dated 2011 and part number 3A0919506 while the 1994 car had an original 1993 item with part number 357919506 but I've checked and they are compatible.

 

I fitted the later part to the 1994 car and the auxiliary water pump works just fine even with ignition off for a few mins.

 

I then put the later part back into the 1995 car and the auxiliary water pump didn't run on with ignition off.

I checked the aux pump using the bridge yellow temp sensor wiring trick which also kicks in the fan and it worked fine so no issues with that.

 

So FCM is fine, aux pump is fine, any idea why no after run for pump?

 

Only difference is that the 1994 car was warmish while 1995 car was stone cold.

 

I've spent the evening trying to work it out and can only conclude that the non-switched power supply to the FCM that runs the pump with the ignition off is to blame or there is a model year change and pump doesn't work with ignition off unless engine is above a certain temp.

 

Can anyone clarify?

Thanks in advance.

[Jim Bowen 1]

You are right. It only comes on when you turn ignition off if the car is hot.

 

Mine comes on at the same time as the fans but only if it rather hot. Not that much when driven normally and shut off.

[andrewchapple 0]

Thanks for the reply Jim.

I have tried the car that ran the aux pump with ignition again but this time stone (icy) cold and just as it did when warm it continued to run the pump for a few mins with just a quick flick on and off of ignition.

I bought another used FCM with the same part number and this didn't run the pump so can only conclude it was faulty.

The timer circuit must be inside the FCM and clearly is quite prone to failure hence why those that test theirs often come back with it not running the aux pump when cold and assume this is correct as so many do the same but I'm not so sure.

Can anyone else with a new FCM and working aux pump check theirs please?

Thanks

[Jim Bowen 1]

Mine seems to run as soon as you turn ignition on (engine not running). Not sure if its running with engine running or not but i can check that.

 

Then when car is over a certain water temp it will run when you turn engine and igntition off, but fans will run at the same time until temp goes down.

 

What about the temp sender on the side of radiator, i know that can cause issues if sending wrong temp to FCM.

[g0ldf1ng3r 15]

Mine seems to run as soon as you turn ignition on (engine not running). Not sure if its running with engine running or not but i can check that.

 

Then when car is over a certain water temp it will run when you turn engine and igntition off, but fans will run at the same time until temp goes down.

 

What about the temp sender on the side of radiator, i know that can cause issues if sending wrong temp to FCM.

 

what you say above is normal Jim & how they should be :)

[Jim 2]

Mine seems to run as soon as you turn ignition on (engine not running). Not sure if its running with engine running or not but i can check that.

 

Then when car is over a certain water temp it will run when you turn engine and igntition off, but fans will run at the same time until temp goes down.

 

What about the temp sender on the side of radiator, i know that can cause issues if sending wrong temp to FCM.

 

Same behaviour for mine. Aux water pump is whirring as soon as you put the ignition on, even when stone cold. Then when you stop the car, the only time it runs on is when the fans are running too.

[Cressa 44]

Where is this pump? I've tried to see what mine does for you but can't hear anything with the ignition on !!

[Jim 2]

It's not exactly loud but you should hear it if you put the ignition on and have the bonnet open. It's a a cylindrical 'thing' about the size of a can of red bull that sits to the back / just behind the coil pack on the right hand side of the engine. Has two coolant pipes (one in and one out) and an electrical connector on it.

 

If you find it and find it's not making a noise, try giving it a tap with a screwdriver and see if it whirs into life. Mine was doing the same (only running intermittently) so replaced it and all is well now.

[andrewchapple 0]

what you say above is normal Jim & how they should be :)

 

Can you tell me how you know this for sure and that it applies to all model year VR6s?

 

The 'Definitive Cooling Guide' (quoted below) says that the aux pump runs on its own for ten mins after switch off at lower temperatures (it can run with the fans at higher temps too) which is not what Jim Bowen's does, he says his only runs when the ignition is off when the fans are also running.

 

"Fans/pump after-run

The controller stays on for 10 minutes after you switch the car off (regardless of temperature) and will maintain power to the aux water pump. Stage 1 and 2 fans will come on if needed (same temps as when the car is running)."

Edited January 15, 2016 by andrewchapple

[stuarttaylor37 13]

Same behaviour for mine. Aux water pump is whirring as soon as you put the ignition on, even when stone cold. Then when you stop the car, the only time it runs on is when the fans are running too.

 

Mine too

[andrewchapple 0]

Anyone speak German?

This factory guide for 2.8 AAA coded engine explains the system in detail but I don't speak German.

 

http://www.volkspage.net/technik/ssp/ssp/SSP_127.PDF

Edited January 15, 2016 by andrewchapple

[Cressa 44]

Finally tested mine. No noise and no power. Found the 5A fuse blown on the fan control module. I now have power there, so this must be it's control, but unfortunately my pump is dead. Where have people got theirs from?? Gutted another expenditure b4 its even roadworthy..

Edited January 23, 2016 by Cressa

[VAG-hag 0]

Finally tested mine. No noise and no power. Found the 5A fuse blown on the fan control module. I now have power there, so this must be it's control, but unfortunately my pump is dead. Where have people got theirs from?? Gutted another expenditure b4 its even roadworthy..

 

http://the-corrado.net/showthread.php?88973-Bosch-VR6-Auxillary-Water-Pump_-0-392-020-024-VW-251-965-561-B

[Jim 2]

Got mine from the eBay link in that thread - no problems, and mega fast shipping.

[Cressa 44]

thanks for the info and recommendation. One on order

[andrewchapple 0]

A further and possibly final update;

 

I bought a bargain new Topran FCM from this Ebay seller;

http://www.ebay.co.uk/itm/171123753650?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Ignore the Ford Galaxy application, the part number matches Corrado VR6 and seems to work OK.

I plugged it in and just started the ignition and straight away even with a cold engine I had the aux pump working.

I then plugged in my 2011 manufactured genuine FCM and didn't get aux pump working straight away so I started the engine for 10 seconds, turned it off and I had aux pump running then.

So I am pretty confident the aux pump should "after run" even with a cold engine as long as engine has been started even if just very briefly, if yours doesn't but does work when the engine is running, the Topran part is worth a go.

[Cressa 44]

Does your car have air con?

[Cressa 44]

[ATTACH]83087[/ATTACH]

So this is what the insides of an auxillary pump is. Means nothing to me as it can not be repaired. Great price for a new one on the link b4 and received within a few days. Only a steady hours job and fitted.

Feeling good as when i switch the ignition on I can now hear a whirring, fantastic. Switch the ignition off and NOTHING. I can understand with it being cold not over running, so warmed the car up so that my fans are coming on. Switched the car off and still NOTHING. No whirring over run when hot so I think I now too need to look deeper into it !!

 

Bloody Corrado's, just when you change something and feel good about it, you realise it isn't quite right and needs more sorting. I suppose that's part of the challenge.

[VW_OwneR_85 2]

[ATTACH]83087[/ATTACH]

so warmed the car up so that my fans are coming on. Switched the car off and still NOTHING. No whirring over run when hot

did it get hot enough for the fans to run after you switched off?, it might not of been hot enough...

[Cressa 44]

Hmm good point. The fans were coming on and off during the engine running. Perhaps it wasn't hot enough. ... I'll have to try that over the weekend. But reading back on here I'm thinking it's going to be the FCM.

The next problem with that is my car has the diavia aircon, so will need to check I have a normal FCM and not some weird one added on.

[Jim 2]

On mine the aux pump is on the whole time the igition is on, but fan has to be actually running with the ignition off, for the aux pump to be running as well. It shuts off when the fan shuts off.

[Cressa 44]

I can understand the principle of that. I'll Have to try it this weekend. It just seems there are differences. .. and the car actually was running okay without the auxillary pump working! !

[Jim 2]

Yeah - they will. My aux pump had been failing for a while honest. I don't think it massively impacts temperatures.. but with it out of the system, it must accelerate wear, with hot coolant remaining in certain places in the block?

[VW_OwneR_85 2]

I can understand the principle of that. I'll Have to try it this weekend. It just seems there are differences. .. and the car actually was running okay without the auxillary pump working! !

aux pump wont effect the cars running at all, its primary function is to circulate coolant around the engine once the engine has been switched off to keep an even temp across the engine until the temp drops {below 90? not sure at the temp} , I bleive its to stop distortion in the head, in the sense that if an area of the engine is hotter or colder or cools down quicker then a different area then with expansion/contraction could lead to problems, I wouldn't worry to much mine doesn't even have an aux pump and has been fine for a long time, I am putting one in though when I can be bothered....

[swiftkid 1]

I don't think the fans need to be on for it to run after engine is switched off, I think it just runs for about 2 minutes providing it's hot. In my experience the aux water pump is the most temperamental part of a corrado, sometimes it works, sometimes it doesn't.

 

If I were you I'd get multimeter out to check voltage, rather than listening for it running.