Overheating 2001 s3

[MRschango]

hello all,
right this all started about a month ago when it got cold. the coolant temp warning light came up on the dash, turned the ignition off and back on again, it was fine. this happened twice more about 2 weeks apart. it has always sat at 75 - 85c on the dash temp gauge with normal driving. but this day i got a light whilst driving, looked down to see the gauge nearly off the scale! pulled over only to be greated with a warm engine not really hot. i went to a mates, car was fine. left 1 hour later and drove for 2miles then then the warning came on.
these are the probs:
1. the fans do not come on when the aircon is switched on
2. changed the thermostat
3. the top rad hose is hot the bottom is cold
4. the heater blows cold until the temp gauge reads 100+ then its only luke warm
5. no gunk to be seen under the oil cap
6. the waterpump seems to work as you can see the water returning to the expansion tank

anyone out there who can help

 

[whatstandwell]

Have you lost any coolant during this time?
The water you see returning to the expansion tank could just be convection currents and not necessarily confirmation that the water pump is working properly. Water pump blades failing on the 1.8T engines is a known issue, it could be your problem. When was the water pump last changed and how many miles have you covered? I don't have any first hand knowledge of what the symtoms are for water pump blades failing, but it sounds like this is most likely to be your problem...

 

[MIKE GTR]

The impellers on standard water pumps are plastic and therefore break 1 by one overtime rather than an all out failure like most waterpumps. I'd get the system blown thru with compressed air, most garages have a tool that can pressurise the system, it may just be a blockage, or it could be a ****** rad

 

[mk1chopper]

The coolant temp warning coming on when your first start the car then goes away or if you turn off the the car and restart doesnt comes back will be the coolant level sensor in the coolant exspansion tank, unfortunatly you cant replace the sensor you have to replace the whole tank, its not expensive just a bit of a ball ache. I'd read you can clean the sensor too which sometimes solves the problem. As for the other issue does sound like your pump blades might have failed if you've changed the thermostat and its still not circulating properly.

 

[golf]

Nearly 90%* of all overheating problems on the 1.8T block is down to the crappy water pump VAG insist on fitting.








* 90% figure is entirely made up, but it's very, very common.

 

[Welly]

90% figure is entirely made up, but it's very, very common.

LOL. Brilliant! It's OK, 60% of statistics are made up on the spot....

Not a dicky thermostat and CTS? Never heard of one going up to 100+ though I must admit...

Maybe that thermostat is stuck closed?