Radiator fan not kicking in!!

[Paulgo]

Hi - how do you bridge the radiator fan on a 3B to check if it's operational? The car overheated last week (and a couple of times since), shooting up very quickly when I got stuck in a line of traffic, coming off the M1 after a long drive to my Brothers, first leg of me hols - water escaping from the expansion tank I think. Ever since then the rad fan hasnt worked at all and with no fan the car quickly overheats if stood. Had a helluva time getting back from me hols in a 8 mile tail back out of Cornwall!!

The stat was recently changed - water seems to be circulating but the fan now isnt kicking in at all. Its possible somethings shorted - all the fuses and relays seem fine. There's a small tube (about ther size of a disposable cigarrete lighter) with blue/red wiring coming out of either end thats attached to the fan housing - dont know if this has anything to do with the fan operation. Its a Nissen rad and the wiring been adapted undeneath also!!

Darent drive the car at the moment in case it boils over again so all help welcome!!

cheers

Paul

[Mark Halligan]

Info for testing here:

http://www.sjmautotechnik.com/trouble_shooting/cooling.html#fan

[s2driveruk]

check the wires on the back of the motor, on mine they are quite tight, if the whole rad assembly is moving about then it could have just moved the connector.....

Make sure its all sound as if it shorts, you can kiss goodbye to the fuse box and circa £500 - BTDT The fan draws something like 50amps to start which if faulty can fry everything as there is no fuse and the wiring is cr*p IIRC.

If you are stuck out on the road and it does it...windows open and full heat on the fan with the ducts pointing out the windows and roof....you can just about maintain a balanced temp if u drive sensible.....

[panzerwagen]

Paulgo your problem seems to be pretty consistent with....

what we owners here in the States have found out. It seems the ground side of the fan has a problem shorting out and disabling the cooling fan causing what you are expierencing. The cure here was too
1/ Fuse the power to the fan.
2/ Replace the connector to the fan (it ususally burns out inside from this problem) with one from a 200 Quattro.
The 200's had the same problem, but in their case the wiring would lead to a small fire!
There are cases of it.
3/ Check the wiring itself along with the relay. They may also suffer from internal damage due to the overload.

[Ski]

my radiator full speed only works. only when its very hot.

I've took it to an electrician to test the system, but he ran away with tail between his legs.

Currently looking for a garage that will test and fix my radiator speeds.

[Paulgo]

Hi guys - thanks for all the info, thats great! Trying to figure out a plan of attack and slowly getting me head around how the cooling system works!

Another thing that I have just discovered tonight is that I seem to have a leak on the auxillary water pump! Its where the pipe coming down from the top hose from the radiator joins the pump - looks to be seal going around the middle of the pump has perished where the pipe joins. I thought I heard a hissing noise when the car was hot - about 2/3 notches above 90 from that area. The hissing will stop suddenly when the temp lowers back towards 90. Dont think Im actually losing a lot of water this way but Im worried that the pump isnt operational!

I now know the odd tube bolted to the back of the fan cowling is indeed the resisitor pack Ive read of (433 959 493A) - looks ok tho not sure how to test it!!.

Other factor that might have nothing to do with this is that the guts of the dealer fit aircon was recently removed when the burst turbo coolant pipe was fixed and the stat changed a couple fo months back, tho I cant see how this can have affected much in this respect. The aircon hadn't worked for ages by the looks, the pipe has two huge holes in it and the drive belt had been removed - the condenser was almost as big as the main rad and had an odd second fan on it.

thanks again!

Paul