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Discussion Starter · #1 ·
Help me fix my car...

It's overheating but just while I'm moving . it idles fine ,,,,

I found out the electric cooling fan it's not working , does anyone have the schematic of the cooling system and the control of the electric cooling fan ?

I know it sounds like waterpump or thermostat but i wanto find out , why the electric cooling fan it's not turning on ( no svoltage going to it )

TIA

Fabio
 

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The cooling fan is most likely to be necessary when stationary. When you are moving there's quite a wind anyway and the fan wouldn't do much. It seems more likely it's the thermostat, like barticus says above.
 

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Fabio the switch that turns on the fan is right over the lower radiator hose. It is a thermostatic switch that make contact when the temp get hot enough.

The eletric fan you only come on when you temp is really high or when you turn on the A/C.

The clutch fan is what does most of the work of cooling the radiator.

So you have either one of two problems and not any of the guesses that were made up above.


Scenario #1: The thermosat if stuck closed and the water in the block gets too hot and start to boil out of the block from the upper rad hose. this will happen after you drive or run the engine for a 10 to 20 minutes.

Scenario #2: The clutch on the radiator cooling fan is gone and the fan is just spinning freely, so fan may not be spinning at any speeds above idle.


To check the radiator fan hold the fan blade and spin it if there is no tension on the fan blade from the clutch then you need a new clutch.


If you can't remeber when last the thermostat was changed in your car get a new one put in. This will require draining the cooling system so prepared for that by getting new coolant to replace it with.

Check the fuses for the auxiliary cooling fan and make sure that it is not blown and last but not least make sure that when you turn on the A/C that your electric fan comes on.
 

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Your thermostat is stuck closed. If you let it idle long enough it will overheat. The thermoswitch is probably in the radiator, so if the thermostat is always closed, the radiator collant won't heat up. If it were the waterpump, I think it would heat up very quickly at idle.
 

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Discussion Starter · #8 ·
Thanks guys .

so far I diagnosed this.

the belt driven fan seems to be ok , radiator is cool , electric fan it's not spping at all.

The car wont everheat in idle no matter for how long i leave it in idle.

No blown fuses and the electric fan does not turn on with the AC .

The coolant it's not boiling and there is no steaming coming out of the hoses/ caps .


I think the problem is the thermostat too , does anyone know if there is a write up in replacing the thermostat ?

Can i re use the coolant ? or it s a good idea to replace the coolant ?. I know the coolant was flushed 20,000 miles ago.

Fabio
 

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I'm really surprised that the car won't overheat at idle. That may just be because of the location of the sensors.

I would use fresh coolant. It's hard to drain the system without getting contaminants in it.

1.8Tabamoura said:
Thanks guys .

so far I diagnosed this.

the belt driven fan seems to be ok , radiator is cool , electric fan it's not spping at all.

The car wont everheat in idle no matter for how long i leave it in idle.

No blown fuses and the electric fan does not turn on with the AC .

The coolant it's not boiling and there is no steaming coming out of the hoses/ caps .


I think the problem is the thermostat too , does anyone know if there is a write up in replacing the thermostat ?

Can i re use the coolant ? or it s a good idea to replace the coolant ?. I know the coolant was flushed 20,000 miles ago.

Fabio
 

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unfortunately I haven't replaced a thermostat in a VW, as my last one before my passat was 79 bus.(air cooled) but in the other cars I have done, you can remove and rpelace it with only dumping a little bit of coolant as it is normally located near the top of the radiator. But saying that it is always a good idea to flush and replace coolant when you do this as a lot of times the problem is dirty coolant causing the old thermostat to get gummed up. Clear as mud? :???: :D
 

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Along a similar topic, does anyone know how to bleed the cooling system on a B5.5? I have it down pat on a BMW E34 (just sold!! Woohoo!!!), but this would be a good thing to know about our cars.
 

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Fabio it is easy to change the thermostat.

1. Jack up the car and take off the belly pan.
2. There is a bracket the attaches behind the crank pulley remove it (this will make it easy to remove the thermostat housing)
3. place a bucket under the water pump and remove the drain bolt
4. After most of the water has drained out (there may still be a little in the hoses) remove the two 10mm bolt that hold the therostat housing in place.

Reassembly is almost the reverse of removal. of course you will have to make sure that all the hose are back in place and that there are no leaks.

When you refill the car with coolant you may want to disconnect the top rad hose and use it to fill the engine block. then just go back and fill the rest through the coolant tank.

The bently manual had some bleeder hole on one of the heater hoses but I never found it (if you find the bleeder hole then you would fill the radiator start the car and turn on the heater and this would fill the engine block if you don't get water in the block the thermostat will not get hot and open when it is supposed too and the car will overheat again because the water in the block is not circulating.

I hope this help you Fabio.

I'm audi 5000
 

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The coolant isnt too much $$ Fabio. I picked up 2 of them at cambridge VW, hate the service there, but fine buying stuff. Good luck!
Ryan
 

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Discussion Starter · #15 ·
ok some news :

the thermostat i removed looked clean and i put in boilng water to check it if it was working i seems fine ,it opens a lot and smoothly then when i put it in cold water it closes .

Maybe my water pump is gone ..

Fabio
 

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phantom GLI said:
Fabio the switch that turns on the fan is right over the lower radiator hose. It is a thermostatic switch that make contact when the temp get hot enough.

The eletric fan you only come on when you temp is really high or when you turn on the A/C.

The clutch fan is what does most of the work of cooling the radiator.

So you have either one of two problems and not any of the guesses that were made up above.


Scenario #1: The thermosat if stuck closed and the water in the block gets too hot and start to boil out of the block from the upper rad hose. this will happen after you drive or run the engine for a 10 to 20 minutes.

Scenario #2: The clutch on the radiator cooling fan is gone and the fan is just spinning freely, so fan may not be spinning at any speeds above idle.


To check the radiator fan hold the fan blade and spin it if there is no tension on the fan blade from the clutch then you need a new clutch.


If you can't remeber when last the thermostat was changed in your car get a new one put in. This will require draining the cooling system so prepared for that by getting new coolant to replace it with.

Check the fuses for the auxiliary cooling fan and make sure that it is not blown and last but not least make sure that when you turn on the A/C that your electric fan comes on.

Exactly what i was talking about....THAT thermostat switch, sorry i didnt throw in the "thermostatic".

-Dalip-
 
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