Radiator fans wont come on - Page 4

audiqv8 · 05-07-2012, 08:49 AM

Quote:

Originally Posted by gcpgcp

I am reading this thread with interest, thank you for all your information!!

I found the other day that my coolant expansion tank is cracked and leaking so it must be replaced but could lack of pressure cause the thermostat to remain closed? The lower hose remains cool to the touch while the upper is hot so I am thinking I may have a bad thermostat, a bad water pump or a bad sensor. How do I verify which is the actual culprit? When AC is on the fans turn properly but will not turn on otherwise.

You have a clogged radiator, both top and bottom hose should be hot. The temperature sensor is located at the bottom of the radiator. In order for the fan to turn on, the bottom hose needs to be hot.

gcpgcp · 05-07-2012, 03:18 PM

Quote:

Originally Posted by audiqv8

You have a clogged radiator, both top and bottom hose should be hot. The temperature sensor is located at the bottom of the radiator. In order for the fan to turn on, the bottom hose needs to be hot.

You are right audiqv8, I measured the temps and after the car idling a while the upper radiator hose read 199 deg while the lower read 105 deg. Right at the engine the lower read 151 deg, The radiator read 206 deg on the right middle and 105 and the left middle. It is evident that the temperature is not even across the radiator so I bought a flushing liquid from Advanced Auto to flush out the radiator. They also recommended a flushing kit but that would necessitate cutting a heater hose but I'm reluctant to do so. In your opinion, what's the best way to flush the system out with a water hose without cutting a heater hose?

audiqv8 · 05-07-2012, 04:48 PM

You could try flushing the radiator. Just buy a length of heater hose and disconnect one end of the existing hose and use the new one. Then place the flush tee between the new hose and existing heater hose. This way you don't have to cut your heater hose.

A better way would be to remove the radiator and bring it to a radiator shop and have them boil out the radiator. Or just buy a new radiator.

gcpgcp · 05-07-2012, 05:17 PM

Great idea! BTW, is this Prestone flush liquid ok to use in an Audi engine?

audiqv8 · 05-07-2012, 05:50 PM

You have an aluminum engine with an aluminum radiator, therefore check that the chemical is safe to use.

gcpgcp · 05-07-2012, 06:02 PM

There's nothing written on the container so I'll search on the net and report back.....and it's PEAK radiator super cleaner and flush not Prestone.

gcpgcp · 05-07-2012, 06:21 PM

Absolutely nothing on the net about the chemical composition of this peak product and/or if it'll be damaging to aluminum components so I guess I'll just use water so as not to hurt anything. So, I'll drain the coolant, fill with water, run the car, drain & refill with water a few more times to get the gunk out, as much as possible, and finally fill with 50/50 coolant mix and distilled water

audiqv8 · 05-08-2012, 10:20 AM

I doubt that just flushing with water will fix the problem.

gcpgcp · 05-08-2012, 03:26 PM

The car will be going to the mechanic in the morning to resolve this and other issues as I'd sure like to get my 1994 back into tip-top shape. I'll keep you posted on how things turn out.

I very much appreciate all your help, this is a great forum to be part of!

dubblrest1985 · 05-09-2012, 11:09 AM

I did replace the sensor a while back. I will remove it and true a flush! It seems as is this is my problem.

Thanks guys!!

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05-07-2012, 04:48 PM	#33
audiqv8 AudiWorld Super User Garage is empty, add now Join Date: Apr 2002 Posts: 3,041	You could try flushing the radiator. Just buy a length of heater hose and disconnect one end of the existing hose and use the new one. Then place the flush tee between the new hose and existing heater hose. This way you don't have to cut your heater hose. A better way would be to remove the radiator and bring it to a radiator shop and have them boil out the radiator. Or just buy a new radiator.

05-07-2012, 05:17 PM	#34
gcpgcp Audiworld Junior Member Garage is empty, add now Join Date: Dec 2006 Posts: 16	Great idea! BTW, is this Prestone flush liquid ok to use in an Audi engine?

05-07-2012, 05:50 PM	#35
audiqv8 AudiWorld Super User Garage is empty, add now Join Date: Apr 2002 Posts: 3,041	You have an aluminum engine with an aluminum radiator, therefore check that the chemical is safe to use.

05-07-2012, 06:02 PM	#36
gcpgcp Audiworld Junior Member Garage is empty, add now Join Date: Dec 2006 Posts: 16	There's nothing written on the container so I'll search on the net and report back.....and it's PEAK radiator super cleaner and flush not Prestone.

05-07-2012, 06:21 PM	#37
gcpgcp Audiworld Junior Member Garage is empty, add now Join Date: Dec 2006 Posts: 16	Absolutely nothing on the net about the chemical composition of this peak product and/or if it'll be damaging to aluminum components so I guess I'll just use water so as not to hurt anything. So, I'll drain the coolant, fill with water, run the car, drain & refill with water a few more times to get the gunk out, as much as possible, and finally fill with 50/50 coolant mix and distilled water

05-08-2012, 10:20 AM	#38
audiqv8 AudiWorld Super User Garage is empty, add now Join Date: Apr 2002 Posts: 3,041	I doubt that just flushing with water will fix the problem.

05-08-2012, 03:26 PM	#39
gcpgcp Audiworld Junior Member Garage is empty, add now Join Date: Dec 2006 Posts: 16	The car will be going to the mechanic in the morning to resolve this and other issues as I'd sure like to get my 1994 back into tip-top shape. I'll keep you posted on how things turn out. I very much appreciate all your help, this is a great forum to be part of!

05-09-2012, 11:09 AM	#40
dubblrest1985 Audiworld Junior Member Garage is empty, add now Join Date: Dec 2008 Location: new york Posts: 61	I did replace the sensor a while back. I will remove it and true a flush! It seems as is this is my problem. Thanks guys!!