Too Tall 10 Posted February 23, 2016 So my axillary water pump isn't working, New one is on order. My question is this, if the pump isn't working could this be keeping my thermostat from opening? After I drove the car to work today I felt the radiator hoses, the upper was hot, but the bottom hose was cool to the touch. Any ideas? The water pump and thermostat are both brand new to. Quote Share this post Link to post Share on other sites
seanl82 23 Posted February 23, 2016 No, the aux pump just circulates the water after the engine is switched off when at a certain temperature. Quote Share this post Link to post Share on other sites
VRTRIZZ 10 Posted February 23, 2016 Done away with mine. Quote Share this post Link to post Share on other sites
Too Tall 10 Posted February 23, 2016 Going to get rid of mine. New question, I've been having problems getting my fan to shut off, found a blown fuse on the fan control module replaced it but it didn't change the problem, I have a new radiator fan switch on order. The other day I thought I might have accidentally switched the plugs for the ac cutoff and the temp gauge sensor. Apparently I didn't, but when I switched them back now my temp gauge doesn't work. Is there a fuse somewhere, or did I fry the gauge? Quote Share this post Link to post Share on other sites
Jim 1 Posted February 23, 2016 VW put it there for a reason - I wouldn't personally be in a hurry to delete the aux pump. They only cost buttons and are a 15 minute job to replace at most. Quote Share this post Link to post Share on other sites
britpop95 0 Posted February 25, 2016 Ye for me the aux pump keeps pressure of the matrix. I put a new one on after the plastic outlet pipe corroded away taking a lot of coolant with it. Quote Share this post Link to post Share on other sites
john46 10 Posted February 26, 2016 Mine runs as soon as the ignition is on I take it I will need a new one then as its knackered ??? Quote Share this post Link to post Share on other sites
VAG-hag 0 Posted February 26, 2016 No John, mine runs on ignition too. They are supposed to Quote Share this post Link to post Share on other sites
Jim 1 Posted February 26, 2016 Yep - as soon as ignition is on, the pump should be whirring. That's correct behaviour. The pump will also be running even with ignition off IF your cooling fan is running though you won't be able to hear it. You can simulate this by bridging the appropriate pins on the coolant temperature sensor connector on the radiator (which will bring the fans and the pump on) but then disconnect the fan and ensure your pump still runs when you re-bridge the connections. The scenario I'm not sure we've been able to 100% agree on is whether the pump should run on every time after the ignition has been on, regardless of if the fan has been running or not? In my case, when the ignition is off, and the fan isn't running, the aux pump doesn't run - I'm pretty sure this is how it should be. Quote Share this post Link to post Share on other sites
VAG-hag 0 Posted February 26, 2016 Mine is same Jim. I would like it to run for 5 mins after shutoff though..... Quote Share this post Link to post Share on other sites
Jim 1 Posted February 26, 2016 Mine is same Jim. I would like it to run for 5 mins after shutoff though..... I guess if you installed a lower temperature fan switch in the radiator, that might take care of that? Though would mean the fan was on more often which may or may not be desirable. Quote Share this post Link to post Share on other sites
john46 10 Posted February 26, 2016 Cheers guys that's alright then :cheers: Quote Share this post Link to post Share on other sites
VW_OwneR_85 1 Posted February 26, 2016 Mine is same Jim. I would like it to run for 5 mins after shutoff though..... yea that's what I would like too, I currently don't have one fitted to my 24v swap as I didn't realise the wiring for it was on the 12v engine which I sold :( , but its on my things to do list!, how ever I don't think rados aux pump is meant to come on without the fans, I don't now if this is going to be easy but I know the mk4 v6's aux pump comes on after shut down regardless of temp, it comes on and stays on for ahwile even if you only start it for 1 minute. looking at the wiring diagram for mk4 the power for it comes from the fan control module the same as corrado but I wandering if the mk4 FCM has a timer switch instead of corrados temp switch? it might be as easy as getting a mk4 FCM with the two plugs and matching it up for that function? dunno I'll look into it... Quote Share this post Link to post Share on other sites
Ray1965 10 Posted September 26, 2018 Looks like I have a leak on my Aux water pump. been in contact with VW as i also have a leak on the thermo housing, so got quote on them both. £60 for housing with all the o rings etc and £162 for new pump. Question is can I delete it from the car and how? and run ok without it? Does anyone know of a cheaper replacement pump that they have used? Quote Share this post Link to post Share on other sites
fendervg 29 Posted September 26, 2018 You should be able to get a pump for less than that if you shop around on the secondary market. Some folks have deleted them and not had any problems - personally I would replace it to be on the safe side. If you are going to do the thermostat housing, budget on new temp sensors, stat, and crack pipe as well. It's not a job you want to do twice in a hurry as the front end needs to come off for access. In my experience replacing one component on an older cooling system will soon lead to a failure somewhere else due to increased pressure, and if I had to go there again I would simply save up and replace the whole lot (pump, stat, hoses, matrix and rad) all in one go. Quote Share this post Link to post Share on other sites
a_riot 0 Posted September 26, 2018 In my experience replacing one component on an older cooling system will soon lead to a failure somewhere else due to increased pressure, and if I had to go there again I would simply save up and replace the whole lot (pump, stat, hoses, matrix and rad) all in one go. That seems excessive to me. OE VW hoses and radiators last decades, so I don't replace them unless they are blown or about to blow. I've replaced many cooling components as needed and never had an issue, as I think the components that came with the car are superior to what we can get now. However, I think that VR6 engines that have leaky head gaskets pushing combustion pressure into the cooling system can suffer from ongoing cooling system failures, so that definitely does occur without owners realizing it. If you suddenly start blowing hoses and finding leaks, the head gasket might be the culprit not the cooling system components. Quote Share this post Link to post Share on other sites
Cressa 43 Posted September 26, 2018 I got a the same Bosch auxillary pump off eBay last year. Was about 50 pounds and came with a can of silicone aerosol. Brand new from a seller in Germany, same place as others had recommended on here. Perfect fit too Quote Share this post Link to post Share on other sites
Cressa 43 Posted September 26, 2018 I don't have the balls to delete the pump as the VW masterminds put it there to keep our hot engines cool even after we switch off and walk away. You can get cheaper parts I suppose.... coincidentally I have just started collecting all the genuine pipes and hoses, damn that bill does add up against other suppliers. Good luck in what you decide Quote Share this post Link to post Share on other sites
fendervg 29 Posted September 26, 2018 That seems excessive to me. OE VW hoses and radiators last decades, so I don't replace them unless they are blown or about to blow. I've replaced many cooling components as needed and never had an issue, as I think the components that came with the car are superior to what we can get now. However, I think that VR6 engines that have leaky head gaskets pushing combustion pressure into the cooling system can suffer from ongoing cooling system failures, so that definitely does occur without owners realizing it. If you suddenly start blowing hoses and finding leaks, the head gasket might be the culprit not the cooling system components. What you say should be the case, but my experience was otherwise unfortunately - this on several Mk2s, a Mk3 and an Audi Coupe. All with original components as well - I think the problem is just the age of the components. In terms of quality you can still get most of the stuff from VW or OE suppliers (at a price) and the quality is as good as original. The only part you will really be stuck on is the hoses as these are not all available, so silicone is your only option. If you stick with VW, Bosch, Hella etc, you should be good. I just got tired of draining and refilling the cooling system each time another bit went - I must have shares in whatever company brews G12 by now! Quote Share this post Link to post Share on other sites
Cressa 43 Posted September 26, 2018 https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F382434442180 Hopefully a working link Quote Share this post Link to post Share on other sites
a_riot 0 Posted September 26, 2018 What you say should be the case, but my experience was otherwise unfortunately - this on several Mk2s, a Mk3 and an Audi Coupe. I have found that Corrado parts are significantly superior to A2/A3 parts in general. They were just built better than the VW products sold at the time imho, with some notable exceptions, so I'm not sure you can extrapolate from other VWs. For instance, when I replaced the head gasket on my lower mileage Corrado (100k miles), I had planned on replacing the upper chain guides and plastic cooling parts at the same time. But looking at the guides, they looked brand new, as did all the cooling plastic housings. So they all stayed where they were and are still going strong 15k later. The same parts purchased today aren't going to last that long from VW or elsewhere. They just don't make them like they used to, so I'd be hesitant to replace things that aren't broken with parts from the modern era, as they just aren't as durable. They figured out how to cheapen them while still looking similar. Quote Share this post Link to post Share on other sites
Ray1965 10 Posted September 27, 2018 https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F382434442180 Hopefully a working link Cheers Cressa. Thanks to everyone for your comments. Quote Share this post Link to post Share on other sites
Cressa 43 Posted September 27, 2018 http://the-corrado.net/showthread.php?88973-Bosch-VR6-Auxillary-Water-Pump_-0-392-020-024-VW-251-965-561-B And this Quote Share this post Link to post Share on other sites
