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Waterpump dead? But not overheating?

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by mookie, Nov 14, 2012.

  1. mookie
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    mookie Member

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    I replaced my thermostat at the weekend for a couple of reasons, firstly as the temp gauge wasn't going over 70 when driving, and secondly the radiator fan wasn't kicking in - ever. It's an A4 1.9tdi 2003. Bled the coolant properly, no signs of airlocks etc.

    New thermostat in, and the coolant sits dead on 90c once the car is driven a few miles. Never rises above 90c, vents put out hot air, MPG seems about right etc. Nothing untoward at all.

    Except the radiator fan (unless I miss it happening) never seems to come on. I'm used to, in my previous cars, having the fan over-run for a little bit once I reach my commute destination (mix of traffic jams and motorway). But in the A4 it's never running when I stop... does the A4 tdi run really cool naturally? I checked the rad hoses, top one is hot, bottom one was very vaguely luke warm, expansion tank pipe was hot too. All the pipes were nice and soft and not rock hard over pressured.

    What temp is the radiator fan meant to kick in at? It's getting up to a solid 90c after 5-8mins or so of driving, with another 20-25mins of driving after that before stopping.

    Options are an impeller-less waterpump, or a duff fan connection/switch/fuse. But the solid 90c and cold bottom pipe is confusing me as I'd have thought it would have overheated in those circumstances?
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  2. lgooch
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    lgooch Member

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    I have never heard the fans on my A3 1.9 tdi come on at all. Don't forget diesels are more efficient and don't create as much heat. My old 1.8t golf used to have the fans on all the time. Literally took minutes to get up to 90 c from a cold start. Diesels in comparison take ages
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  3. mookie
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    mookie Member

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    Hmmm that would make sense. To be honest I am comparing this to a Corrado Vr6 and every Mk2 Golf I ever owned... possibly not a good comparison? Ha ha ha
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  4. stu_m
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    stu_m Active Member

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    Have you got two electric fans or one electric and one viscous?

    If one of each then the electric one would only come on with the air con and the viscous would be on all the time but you can't really hear it

    Though these engines are really efficient and take ages to get the fan on

    Seems normal to me
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  5. mookie
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    mookie Member

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    No viscous fan, and I could swear there's only one electric fan... unless the other one is under the cowl cover on the driver side of the rad?

    What does it take to get the temp up high enough then? Lots of motorway or jams?
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  6. lgooch
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    lgooch Member

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    Take it for a spin
    Bring it home and park it nose first against a wall
    Rev it to 2000 rpm and keep it there for 10 minutes
    See if the temp climbs and the fans come on

    I know when I left my 2.0 tdi ticking over after being at 90 C the temp dropped after half hour. I was trying to dry my seats at the time as my little girl was playing with the keys and must have opened all of the windows. It was left overnight and it chucked it down.
    I had water running out of my speaker grills for 3 days.

    Anyway off post but it should heat the car up nicely
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  7. stu_m
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    stu_m Active Member

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    Yeah should be another fan behind the cowl which will be for the air con

    If its not overheating then I wouldn't worry about it
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  8. benjie
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    benjie Member

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    The only time my fans have come on in 4 years of ownership is when the wiring harness to the coolant temperature sensor fell off ("someone" hadn't pushed it back on hard enough when he changed the CTS!) then the fans went on and they were not noticeable when driving, but LOUD when you got out the car! I would say you're fine, but feel free to unplug the CTS wiring harness to test if they work!!
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  9. dale86
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    dale86 Member

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    I would get it checked out mate mine did simlar thing about two month ago then suddenly temp gauge shot thru roof and blew a blanking bung out the side of the engine spewing all the coolant out. It turned out to be water pump failure which is apparently pretty common if not serviced when scheduled which mine was just due to be done timing kit fitted and new pump and luckily no other damage done as I quickly shut it off.
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  10. marktdisport
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    marktdisport Active Member

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    Don't worry !! Time to worry when it goes above 90oc...... The viscous fan is very quite
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