water temp question

I would first test the fan thermoswitch.

Try this - next time it gets hot, turn on the A/C. This should force the engine cooling fan on. If it immediately cools off I would strongly suspect the thermoswitch. It's that big thing that screws into the tank of the radiator, with a little molded plug. If you have the quickness, you can probably R&R it without draining the coolant.

good luck,

nate

Chris E wrote:

collapsed hose?

What makes you think the car is running hot? Spewing antifreeze solution?

Turning the heater on is giving you extra cooling capacity so that would explain the temp drop to an extent.....but starting at the beginnning:

If everything is running normally and all fans are working etc then whether you have the heater on or not shouldn't affect the temperature - the Thermostat & electric cooling fan will just compensate for variations in engine temp caused by traffic conditions etc and that should result in a pretty stable temperature on the guage "whatever the weather" - so something is not right.

If the car is running at normal temps when running at speed (i.e. not stuck in traffic) then it could be a variety of things

The electric fan thermoswitch may not be working - to test just switch the car on & watch the temp climb. At some point (as it heads past "normal" - which should be around 190 deg F) the fan should come on - if it doesn't then that needs correcting & is probably the root cause of the issue.

If the fan does come on and the temperature continues to rise (or won't fall towards normal) then you know you have a cooling problem this could be:

a) A shortage of coolant (and if so the next step is to find out why) b) A massive airlock - but unless soimething has been done to the system recently this is unlikely c) a flow restriction -collapsed hose, blocked radiator or possibly (but unlikely) a sticking Thermostat. As they get old thermostats tend to stay open longer than they should (because the spring gets weak) resulting in low running temps d) The water pump is on its way out

In amongst all this it may well be that you just have a bad temperature sender - VAG senders don't last forever & often need replacing - not expensive. You could possibly also have a bad guage - this is pretty unlikely though since it seems to be registering temperature changes.

HTH

I.

No - no antifreeze spewing. Just the climb up the guage. When the car is at speed out of traffic the temp stays right at dead center on the guage. Its when I get back into traffic that it starts to heat up. It hasn't got above

-Chris

It was common for them old cars to run close to the limit. Mine always ran about just above 3/4 until the AC came on and it dropped.

With more recent VW cars it is so that the temp gauge is more or less fixed in the middle at a certain temp range and only goes over or under this middle position when the temp is outside a certain range. This is done so that less people are calling the dealer on why the temp is so high or low...

Remco

Correct, most(maybe all 98up) of our newer cars stay ay 190 eventhough the temps can be anywhere from 180-220 degrees.

sounds kinda normal to me except maybe your radiator fan might not be coming on. my '91 GTI will get to about 2/3rd up the scale before the fan kicks in if i've been sitting in heavy traffic.