Normal Temperatures

[Robnelson76]

Hi folks,

I picked up my A6 2.5 Tdi Quattro (02 plate, 153,000 miles, FSH) yesterday and drove it about 50 miles back home.

The coolant temp never got above the second line (I'm guessing 80 degrees) and most of the time seemed to be around the first white line.

The oil temp never moved past the first white line (I'm guessing 80 degrees).

The handbook simply says the coolant will settle "somewhere in the middle" and oil temp should not be on the left hand side.

I wasn't driving hard, but the trip took about an hour and it was fairly mild (10 degrees ambient temp).

I did notice a couple of times when accelerating that I could hear water bubbling / gurgling behind the dash.

The cooling system seemed to pressurise OK - it hissed as I undid the expansion bottle cap and the level seemed ok.

What should I expect as normal for the car?

Rob

[kite]

Check the bulkhead drains. Engine temp should sit at 90. You could have a faed thermostat

From a phone that's smarter than me...

[Peter D]

It should rise to 88/90 degrees and stay there. As detailed it indicates a failed thermostat, quite common. Search on plemum chamberfor your water noise. Regards Peter

[Robnelson76]

Looks like quite a job to change it; will it cause issues in the short term if the thermostat has failed?

[kite]

Engine will not reach operating temp. Could affect MPG. Did you find water in the bulkhead?

From a phone that's smarter than me...

[Robnelson76]

The plenum chamber was dry. I'll see how the thermostat goes but it seems a huge job to get it changed.

My other car is a Mk 4 golf with a shot thermostat ..... Argh :-(

[kite]

With the age and miles on the car it might be worth investing in cambelt kit, waterpump and star for peace of mind

From a phone that's smarter than me...

[Robnelson76]

I know the cambelt is due at 160,000. I wouldn't necessarily change the water pump at the same time (unless there's evidence of leaks etc).
The thermostat may have to wait for 6k miles as I think i will be in need of four new tyres before then... It's all a question of money...
What is the star you refer to?

[Peter D]

Increased fuel consuption and in the longer term incresed wear. You would be fool hardy to not change the water pump with an OEM one along with the entire genuine cam belt kit. If you have to wait wthen cover up 60/70% of the radiator. Regardfs Peter

[Robnelson76]

Thanks. Any suggestions on what with/how to cover part of the radiator?

I am still a little confused as to the rationale for a water pump replacement alongside a cambelt. I know that Audi recommend it as part of the cambelt change, but I always though it was a preventative measure whilst the car is in bits. I've had Mercedes with huge mileages on original water pumps without an issue

[kite]

star was a typo, should read stat.
audi waterpumps are a known weak point, they have plastic implellors which are known to shatter, for the sake of £40 change the pump while the front is off.

[Robnelson76]

Ahhh that makes sense. I'll get it changed when it's all done. Now how do I cover half the radiator??

[NickPicks]

Ahhh that makes sense. I'll get it changed when it's all done. Now how do I cover half the radiator??

You could use cardboard, but it'll get soggy. Try some plastic board (like the stuff they use on estate agent's signs). I'd try using bungee cord to secure it in front of the radiator so it doesn't get sucked into the fans.

[Robnelson76]

I haven't yet covered the radiator, but noticed on a decent run over the weekend that on several occasions the coolant temp gauge would drop from between 75 and 85 degrees to the left most stop (I.e. where it sits when the engine is off).

There was no corresponding change in the oil temp, (sat quite happily at the first line above 60 degrees) and the DIS reported 42 mpg average over 500 miles at 70 mph on cruise.

After a while the coolant gauge sprung into life and rose back to between 75 and 85 degrees.

With the mpg being as good as reported, is it more likely that the thermostat is fine and it's the temp sensor that's shot? And does anyone know where it is on the engine?