1.9 TDI - Water temp higher than normal

[Jack Blag]

My 2003 Audi A6 1.9 TDI's water temperature normally sits at 90 degrees C, but recently the needle has crept up and is now indicating just below 100 degrees C.

Is this due to the colder weather, or is it an early warning sign that something is about to go?

All replies gratefully received!

[Tame Technician]

Water pump failure most likely, could be thermostat stick shut too.

But dont panic just yet, could be temp sensor reading funny.

Check if the cooling system is circulating, Is the rad hot, top and bottom hoses hot, when is shows 100 degrees. If the engines hot and the rads still cold its not circulating.

If you can (lazer thermometer or something) check the actually coolant temp compared with what you got on the gauge.

Heater working ok??

[Jack Blag]

Tame Technician said:

Water pump failure most likely, could be thermostat stick shut too.

But dont panic just yet, could be temp sensor reading funny.

Check if the cooling system is circulating, Is the rad hot, top and bottom hoses hot, when is shows 100 degrees. If the engines hot and the rads still cold its not circulating.

If you can (lazer thermometer or something) check the actually coolant temp compared with what you got on the gauge.

Heater working ok??

The needle rises normally as the engine warms up and drops again if the engine is not under load. It just seems to be showing a higher reading than normal. I presume that 90 degrees is the normal reading on a 1.9TDI?

I'll check the water is circulating in the morning. The heater appears to be working normally.

Thanks for your help!

Edited by Jack Blag on Monday 8th February 19:42

[Tame Technician]

If the heaters ok it is probably circulating, could just be a sensor/gauge issue. Thats where a lazer thermometer is invaluable.

90 is normal, although usually takes a long time to get up there in the winter.

[BoraBora]

id get it checked out, im sure the timing belt spins the water pump aswell, if the pumps gone then its a possibility it might wear out your belt.

[Tame Technician]

BoraBora said:

id get it checked out, im sure the timing belt spins the water pump aswell, if the pumps gone then its a possibility it might wear out your belt.

Yes the cam belt spins the pump, but on the 4 cylinder engines if the pump failes it spin the pump pulley but the impellor inside doesnt actaully pump the water, only danger is overheating.

The petrol 3.0V6's I've seen them when the pump stops dead and strips the belt, (detroys the valve train) but very rare indeed and never on a 4 cylinder.

[Jack Blag]

It's now had a new water pump, timing belt and thermostat... and it is still sitting at 100 degrees. The good news is it doesn't go any higher.

Is this normal?

[Tame Technician]

Its not going to do any damage if it never goes higher than that. But its not normal, they should show 90 on the gauge

Could be a Gauge fault, it happens


Whats the "Actual water temp"

MVB 01 in engine ECU

Or lazer thermometer on a coolant pipe near the top of the system.

[Jack Blag]

Tame Technician said:

Its not going to do any damage if it never goes higher than that. But its not normal, they should show 90 on the gauge

Could be a Gauge fault, it happens


Whats the "Actual water temp"

MVB 01 in engine ECU

Or lazer thermometer on a coolant pipe near the top of the system.

The gauge says 100 but the lazer thermometer says 88... Any suggestions?

[Defcon5]

Change temp sensor?

[Jack Blag]

Defcon5 said:

Change temp sensor?

Did that already (along with water pump, thermostat and timing belt).

[Tame Technician]

It the gauge reads 100 and the water is actually 88, the gauge is most probably faulty.

To confirm you need to see what the sensor is seeing Via the MVB. If it too says 88, then you know its the gauge.

[00161wj]

If you switch the ignition off does the gauge sit higher on the scale than the fuel gauge does?

[Jack Blag]

00161wj said:

If you switch the ignition off does the gauge sit higher on the scale than the fuel gauge does?

The fuel gauge drops to the far left (below the markings), whereas the temperature gauge drops to the first mark (60) when the ignition is turned off.

[Tame Technician]

There you have it, Gauge fault.

Really sorry you had all that other work done (always nice to know the cambelt and water pump are new), but If you look at my first responce. 8th Feb

Tame Technician said:

If you can (lazer thermometer or something) check the actually coolant temp compared with what you got on the gauge.

Everybody goes on about what a rip off main dealers are, and how you simply must go to an indy. At the main dealer, you have technicians trained in fault diagnosis and strick first time fix targets. Unless the car is more than 10 years old its always worth a visit to your local Audi Centre. With the car infront of me I could have diagnosed that in 10 mins max. And thats assuming I didnt notice the gauge not parking in the correct place and actually tested the car.