Hi, I'm new here, but I have to say congrats on this awesome forum. Lots of useful information here!

How the problem first occurred:

I was driving and I I just did 30km of my trip. Then my temperature light came on.

I noticed smoke coming out from under the hood and I stopped my car as soon as I could.

I popped the hood and all the steam was coming from the coolant reservoir. And it was boiling over.

The next day I refilled the coolant temporary with water to check for leaks, but on first sight everything seems fine.

I took the car for a drive to see what would happen and kept a close eye on the temperature.

But after 2km the temperature started rising and the light would come back on.

As soon as the light came back on, I popped the hood and noticed that the fan wasn't even spinning.

With that in mind I went to Google and came across this topic.

More specifically this picture:

and this quote:

Pull the connector off the temp switch on the radiator then short pin 2 to pin 1 and the fan should run @ low speed and if you short pin 2 to pin 3 it should run @ high speed, if this works your temp switch is duff, it does'nt work you have a problem from the fuse to the temp switch plug, if it works on low speed but not high speed the fan control unit (under the battery tray area) is @ fault or the metal fusable links on top of the battery, they often look OK but you need to remove them and check they have'nt fractured

I also have the second connector in the picture.

So..

When I short pin 2 to pin 1, the fan spins.

When I short pin 2 to pin 3, nothing happens.

I checked the fuses on top of the battery, but they all work fine.

The next step was the fan control unit under the battery so I removed my battery.

But my model doesn't seem to have a fan control unit..

Pictures:

I'm not sure what to do now. Do I replace the radiator fan control switch? Seems unlikely to me.

Edited 8 September, 201411 yr by Rubeast

First Welcome to the forum.

If you have a multimeter? you could do a continuity check between the fan temp switch and the fan, Pin 1 of the switch plug (Red/White wire) to pin 2 of the fan motor plug & pin 3 of the switch plug (Red/Blue wire) to pin 1 of the fan motor plug, this is if you don't have the fan control unit, as with cars with the fan control unit shorting pin 1 & 2 will always bring on the low speed fan, but shorting pins 2 & 3 this signal goes through the fan control unit to switch the fan to high speed.

The fact that you shorting pins 1 & 2 did bring the fan ON yet when the car was boiling over means the fan temp switch is faulty.

Thank you for the quick reply!

I will do a continuity check between the fan temp switch and the fan tomorrow when I'm back from work.

I there an easy way to remove the fan temp switch? Because it is inside a hole. Not really easy accessible with a wrench.

Will try to make a picture tomorrow.

Does it matter which switch I order (as long if it has the same connector)?

For example: Will this one do?

Edited 8 September, 201411 yr by Rubeast

That switch is a single temp switch yours should be a dual temp ( 3 pin plug) the part number for that is 1H0959481B

I think I replaced the link before you noticed. Can you check again? :)

The new one links to the 1H0959481B part like you said.

Thanks for the info!!

That looks correct just need to make sure the connector is the same as yours? difficult to tell from the picture

Maybe a stupid question.. but how can I unscrew it?

I measured it and it is a 30mm hex screw, but the wrench head (don't know the correct name) I have is not deep enough.

Either a deep reach socket or a ring spanner if not you'll have to remove the radiator !

Are you quite sure that you haven't overlooked, what might be, the original problem?

If you were stationary for long enough, with the engine running, fair enough - the fan should have 'cut in'.

However, if you were driving along and the engine temperature went way above the normal 90° C, it may well be that the thermostat is faulty ( there should have been sufficient air moving through the radiator to cool it down without the fan running)

Regards

The same thing happened to my wifes car.

It turned out to be a faulty thermostat housing.

What had happened was the needle of the thermostat had worn a hole into the housing and as a result, when the coolant got hot the thermostat didnt have anything to push against to allow the coolant to flow correctly and the pressure just bulit up and got spat out of the filler cap.

This is very common on these engines.

Sorted for under a tenner.

Be careful when undoing/doing up the nasty looking screws on the housing cover, as they go directly into plastic and if you strip the threads, you may end up needing a full housing, which is more expensive and more time.

HTH

Thanks for the replies!

That does seems more likely to be the problem.

I went ahead and took it apart.

Result:

I guess that hole isn't supposed to be in there?

If I'm correct I need part number 032121121B or 032121121J.

So if I buy this one, I'll be fine?

Edited 10 September, 201411 yr by Rubeast

That is the correct part, and from painfull recent (today) experience, I would also replace the thermostat with a genuine VW one 032121110B £17.93 inc tax from VW, on mine the pin once extended wouldn't retract

The pin on my thermostat does seem really long. Is that normal? Maybe it is already broken. What is the best way to test it? In boiling water to see if it opens?

When cold the pin should protrude 3~5mm then in boiling water it extends to around 20~25mm mine was sticking @ 10~12mm so causing the stat to be partially open hence my slow warm up, I bought another from Eurocarparts and that was doing the same, So this afternoon I went to VW and got a genuine one and that works fine

Guess it is also broken in that case. You can see the thermostat in the first picture. You can see it is extended while cold.

Try putting the pin against a solid object and the apply some pressure to the base of the unit and see if the pin will retract, if it doesn't its failed

I would be inclined to fit a new thermostat (as Nige says, buy a genuine VW one) If you don't replace it now, there is a good chance that it will break the new housing too.

Regards

Yeah I ordered one at a VW dealer today. I can go and get it tomorrow. (30 euro in case someone is interested.)

I also ordered the thermostat housing at the VW dealership because if I order it online it will probably take a week to ship to Belgium. Too bad they ask 20 euro for that piece of plastic. eBay is much cheaper :-)

Edited 11 September, 201411 yr by Rubeast

But you can brag about your genuine VW one, rather than apologise for the eBay one

Regards

The car is back up and running!

Thanks to you guys a complete car-noob fixed his own car!

Pictures of the broken parts vs new parts:

Well done!!!

Did you fill the cooling system with the correct coolant?

It should have a 50/50 mix of water and G 13 (available from VW and others.

Regards

Thanks! The coolant reservoir said G12 so that is what I bought and used. Also used a 50/50 mix.

G12 will be fine :) G13 is just the latest version ( Purple liquid!)

Sorry to dig up this up after 4 months.

But it looks like the thermostat is on always open now.

The motor takes really long to heat up now so I checked and the coolant flows as soon as I start the car.

I will open it back up in a couple of days, but does anyone have an idea what it could be?

Could be that ebay part you used getting to hot and sticking