Allroad 2.5tdi 2004 temperature guage

[ben 1978]

Hi everyone,

I have a 54 reg Allroad 2.5tdi which I bought last March, so far its been fantastic with no problem, however over the last few weeks the temperature guage has been up and down. It used to run at 90, no matter how hot or cold the outside temp was, but at the moment its up and down. It never gets past 90 but sometimes doesn't register at all. I have checked the coolant levels and it all seems fine, I haven't needed to top it up at all.
I'm hoping its something straight forward such as the temp sender, but any help would be great.
Also can anyone tell me the location of the temp sender so I can check it, i've had a look but can't see it.

Thanks in advance,
Ben

[bagpipingandy]

the temp sender is right on top of engine, under the engine cover, green colour near front LH/center of engine,

if guage is always low rising near to 90 but never gets there, I would think thermostat but if jumping around check this temp sensor, easy and cheap to replace, thermostat not so easy!!

[Golf tdi Hal]

I agree with BPAndy, most likely to be sender but check the viscous fan is not running at idle, I had both faults ...

[quattroa6]

i just had same fault, changed sender first, took 5 mins, but no joy, use a news paper rolled up to stop viscous fan when engine cold, if u cant stop very possible thats broke. unfortunately for me it was thermostat, cost me £516. changed all belts tensioners same time.

[Golf tdi Hal]

I have some cardboard stuffed between the two radiators now with a gap down one side. The temperature gets almost middle of the gauge now. My viscous fan is stuffed.

[ceilidhalfie]

I agree with BPAndy, most likely to be sender but check the viscous fan is not running at idle, I had both faults ...

Can someone clarify? I thought the viscous fan ALWAYS ran even on idle (albeit lower rpm) as its driven by aux belt and its clutch mechanism. Did you mean the ELECTRIC fan?

[NickPicks]

The viscous fan will run, but won't speed up as much with the engine (the viscous drive slips). The rolled up newspaper (real me use their fingers!) should stop it when cold, otherwise the viscous coupling is siezed.

If it's getting hot with the cardboard, then it's likely that it's the thermostat that is failing.

[Peter D]

Did you change the pump whilst the front was off. ?? Did you use a genuine Audi stat and all parts. Regards Peter