A4 overcooling

golfdiva

Hi

My Dad baought a 1996 Audi A4 recently.Its been giving abit of trouble since he got it.
The radiater fan always comes on even first thing in the morning when the car is cold. Yesterday morning the car cut out after about 10 minutes driving and would not start for about 15 minutes:mad:
Also while he is driving it takes ages for the temp gauge to move to the middle (it never goes to the red) and moves eratically back to cold even after driving a while.
Any ideas whats wrong with the car

Thanks in advance

mike65

Water-temp sender is borked, its telling the system the temp is much higher than it really is so the fan comes on. The dash guage may be related to this or it could be a different sensor.

Mike.

BrianD3

Another possibility is that a previous owner has wired the fan to stay on all the time in an attempt to hide an overheating problem. They might also have taken out the themostat.

Lex Luthor

friend of mine had a '96 A4 and he had trouble with the temp sender on it. Apparently a known issue with those cars. It caused it also to cut out. Its a simple swap and they cost about €25.

golfdiva

thanks for the replys

Another possibility is that a previous owner has wired the fan to stay on all the time in an attempt to hide an overheating problem. They might also have taken out the themostat.

God I hope its not this, I'll try the water temp sender first of all as suggested.

Anybody know off hand where this is located in the 1.6cc engine?

mike65

What year? Anyway whatever the year the sensor will be sticking out of the cylinder head at some point - it looks roughly like this when the wries are disconnected.

http://www.performance-cafe.com/images/059919501a.jpg

Mike.

ongarite

I think its 1996 A4

golfdiva

I think its 1996 A4

thats the one

i'll have a go at changing it tomorrow if its straightforward enough

mike65

Ooops!

Mike.

golfdiva

What year? Anyway whatever the year the sensor will be sticking out of the cylinder head at some point - it looks roughly like this when the wries are disconnected.

http://www.performance-cafe.com/images/059919501a.jpg

Mike.

Thanks Mike now at least I know what I'm looking for

BrianD3

Does the A4 1.6 have a lengthways mounted engine? If so then the fan could be a viscous clutch type rather than electric.

If the fan is electric then the fan switch/sensor could be a different one to the sensor which tells the ECU how hot the engine is. In many cars the fan switch is in the raditor so it's easy to tell the difference

golfdiva

Does the A4 1.6 have a lengthways mounted engine? If so then the fan could be a viscous clutch type rather than electric.

If the fan is electric then the fan switch/sensor could be a different one to the sensor which tells the ECU how hot the engine is. In many cars the fan switch is in the raditor so it's easy to tell the differ

I have a read through the owner manual it it says the fan is electric driven

Andrewf20

I also had a engine temp gauge that always stayed in high blue region on the dash. It was the thermostat that needed replacing. I did waterpump change & coolant at same time although not necessary.

franksm

Hey - just to let you know that I had a related problem with my 230CE - it would run hot in traffic. Fan would never kick in. I jumpered the wire to the fan magnetic clutch and found that it engaged fine, so reckoned the switch/sensor was bad - changed that and hey presto, £23STG later, the fan works as expected. Nice easy fix. I know it's the opposite to your problem, but maybe the switch in the A4 "fails safe" to "always engaged"

Lex Luthor

mike65 wrote:

What year? Anyway whatever the year the sensor will be sticking out of the cylinder head at some point - it looks roughly like this when the wries are disconnected.

http://www.performance-cafe.com/images/059919501a.jpg

Mike.

Thats the one I replaced on my mates one. From what I remeber its near the top of the engine to the side. You'll see the wire harness connect into it. Just pull on the connector to release it. You'll need some coolant mix to refill as some is lost

golfdiva

Hey - just to let you know that I had a related problem with my 230CE - it would run hot in traffic. Fan would never kick in. I jumpered the wire to the fan magnetic clutch and found that it engaged fine, so reckoned the switch/sensor was bad - changed that and hey presto, £23STG later, the fan works as expected. Nice easy fix. I know it's the opposite to your problem, but maybe the switch in the A4 "fails safe" to "always engaged"
Today 17:35

Hi Franksm ...is this the water temp sender you are referring to?

I also had a engine temp gauge that always stayed in high blue region on the dash. It was the thermostat that needed replacing. I did waterpump change & coolant at same time although not necessary.

if the thermostat is gone would a syptom be the fan always comming on?

franksm

golfdiva wrote:

Hi Franksm ...is this the water temp sender you are referring to?

yeah - mine (mercedes) has three pins - two are for a switch built-into the sender that sets the fan going; the third pin goes to the dash-gauge. The latter worked fine, it was the switch that was broken on mine.

Thermostats can cause similar problems (either over-heating or under-heating) so unless you can test (as I did), then you takes your chance At least a thermostat is only 5 quid or so, so it's not a big problem to replace whether it needs it or not. But a fan problem... definitely the sender, or the relay, is what you should look at

crosstownk

Be careful - I'm not 100% sure, but its possible that there is a seperate temperature switch in the radiator that controls the fan. The one in the cylinder head may be just for the ECU and the dash guage. I know this was the case with most VAG cars in the early '90s. I'm not sure whether or not that was still the case in 1996. But its worth checking the rad for a switch first.

The temp guage should be always close to 90C once the engine is warm. And should NEVER go into the red.