Overheating on idle

[GtiStyln]

Ok My MK4 gti is overheating at idle, bascially my thermo fans arnt turning on, i swear i have read about 200 different post on over heating golf on here and vortex but havnt really found anything sort of similar to my problem.

Ok it overheat on idle(which is the thermo fans not coming on) but while driving the car the tempreture doesnt rise above the cold mark. wierd huh.

Lets try solve problem number 1(thermo fans not working)

ok apparantly there is a tempreture switch on the radiator which could be faulty

also there is a thermo fan control module(which i think has a fuse in it i think)

Wheres is this module?

I dont think its the termostat, becuse the water wouldnt circulate, which would make the car over heat(or atleats get pretty hot)

Would these problems be link?

thanks
Shane

[h100vw]

I had a problem like this a couple of months back. The temp would intermittently not reach 90 degrees.

Then it started to overheat, even when you were driving.

The final diagnosis was a broken water pump. The impeller had fallen off the shaft.

The top hose was red hot and the bottom hose stone cold. The heat would travel down the radiator but not far enough down that the fan switch was in hot water. This meant that the fans wouldn't come on.

If you run the car with the bonnet up and squeeze the top hose while revving the engine. The hose will swell up if the water pump is OK and if it isn't then the hose won't move.

You will be looking at circa $500 for the bits to fix it plus labour. I got a new pump, cam belt, tensioner and pulley.

It took about 4 hours to do on my driveway.

Gavin

[99gti]

Check the fuses on top of the battery box. I'll bet $5 it's blown and has probably blown half the fuse box away with it.

[h100vw]

Check the fuses on top of the battery box. I'll bet $5 it's blown and has probably blown half the fuse box away with it.

Mine is like that but the fans still work OK.

That would be cheaper than the water pump scenario.

Gavin

[99gti]

Mine is like that but the fans still work OK.

That would be cheaper than the water pump scenario.

Gavin

Mine has done it also and every now and then I have to give it a wiggle to get the fans to kick in...

[GtiStyln]

Check the fuses on top of the battery box. I'll bet $5 it's blown and has probably blown half the fuse box away with it.

Nah sorry i forot mention all fuse a fine even the ones on top of the battery.

I really hope its not the water pump i only had the timing belt done 20000 ago, i wish i knew it was a common fault then

thanks
shane

[ope126]

In no particular order...

- Coolant Temp Sensor
- Thermostat
- Fan Switch
- Fuses
- Check all Coolant Hoses / Fittings
- Renew G12 Plus Coolant

Run Vagcom; as it should be able to check for abnormalities.

[Jmac]

Staying cool whlist driving rules out the water pump generally, pulse test it mate. To do this squeeze the top rad hose and give it a handfull of revs and you should feel the pipe swell if this happens then the pump is working. Staying cool would then be a stuck open thermostat or opening too early around the 50 degree mark. Also could be a faulty temp sensor but have a feel of the pipes and gauge that for yourself, if the stat is opening early then the pipes will be heaps cooler. As for the cooling fans put your air con on fans should cut in 1st speed. If not and they run 2nd speed intermittantly then one of the fans has shorted out but normally takes out the fuse block with it, with the aircon on the fans should come on straight away. If yes then you sre looking at what bring them on when hot and yes this would be a fan switch.
Good luck
Jmac

[GtiStyln]

oh ok, i have no fans when the ac is switch on

[Jmac]

Definate fan or fan feed fault then for the overheating. These MUST run when the AC is activated as they keep the temp down on the condensor thus the pressure stays down. Ac will work crap too then mate. Check if you are getting power to the fans at the source(fans) Changed more of them fans than u can imagine mate hey. Some used to come in for a service and we would fit fans!!!!!
Good luck mate and shout up if you need a diagram or wiring colour references. As for the low temp when driving i would check temp switch and thermostat
JMac