A4 Overheating

**Adam A41.8T** · 05-07-2009,04:14 PM

Hi,

Can anyone help?

I have a 2003 A4 1.8T quattro sport. The temperature guage has never worked roperly which I have read is a common fault but I have never got round to changing it. It used to go up to 90 and then drop back down to zero. Now though it will sit at 90 after the engine has warmed up and if I do about 70 or 80 mph the temp guage starts going right up to 130 and says it is over heating. I can hear the water being pumped around the engine from the coolant reservoir so I am just wondering if it could be the faulty sensor on the temp gauge and that the car is in fact not over heating but it thinks it is. It is not losing any water and is at the max coolant level.

Thanks

**rhencullen1989** · 05-07-2009,05:23 PM

I would think it's either the thermostat or the waterpump, obviously the thermostat is the cheapest/easiest option.

The waterpump should be replaced along with the cambelt (60K or 5 yrs on 1.8T)

Its up to you to use OEM plastic impellor or aftermarket metal impellor, mine is running metal impellor with no probs.

By the way, the waterpump can still pump water around but not at 100% efficiency if the impellor is damaged/partly broken away. If it spins on the shaft it may not pump at all.

**rhencullen1989** · 05-07-2009,05:25 PM

Oh, sorry, forgot to say, the temp sensor can also cause problems, easier to do than the thermostat, no need to drain coolant. probably the first thing to replace.

**Adam A41.8T** · 05-07-2009,07:03 PM

Well the car has done 70k now and I dont think the water pump has been changed yet. DO YOU KNOW HOW TO CHANGE THE WATER PUMP AND HOW MUCH IT WOULD COST?

**Issac Hunt** · 05-07-2009,07:58 PM

Originally Posted by Adam A41.8T

Well the car has done 70k now and I dont think the water pump has been changed yet. DO YOU KNOW HOW TO CHANGE THE WATER PUMP AND HOW MUCH IT WOULD COST?

No need to shout! To change the waterpump you need to remove the front of the car. Not too bad a job if you are handy with spanners? 3-4 hours work ish.

The cost will depend on the labour charge you have to pay therefore we cant give you a price for it.

**Adam A41.8T** · 05-07-2009,08:40 PM

Sorry, I put caps on and when I realised I couldnt be bothered to delete it and start again! Sounds tricky then for me to do by myself. Do you think it is the water pump that is faulty?

**kite** · 05-07-2009,09:03 PM

Change the sensor first then see if the gauge still reads high.....

**Adam A41.8T** · 05-07-2009,09:10 PM

I have read lots of cases on here where the sensor causes the temp to stay at 90 and then drop to zero which mine was doing before. Does it also cause it to read high? Is changing the sensor quite easy to do?

**kite** · 05-07-2009,09:16 PM

A faulty sensor can read all over the place.
A tip on changing. COLD engine, remove rad cap to release any pressure, replace cap to seal. this will keep coolant loss to a minimum. change the 'o' ring and clip at the same time.
You might find a 'how to' on there somewhere.....