chaps looked on forum for the answer with no luck so far.

 

Have nearly 4 yr old 140 CR DSG 4x4 done 97K .

I am use to temperature gauge pointing straight up after say 10 - 15 mins of every journey and oil temperature on maxidot closely following.

Recently gauge and maxidot oftern lower than 90 and gause today AFTER 35 mile mototrway journey dropped to near horizontal i.e down to wards the 50 oC.

 

Can this happen is it ever normal and more importantly should I be seriously worried.

Has a fan or something come on in engine bay ? and I am noticing perhaps drop off in MPG same journey would be 60 mpg today 53mpg or thereabouts

 

Thanks for any thoughts especially if serious issue

 

Simon

Sounds like a faulty thermostat

 

Could be the fan stuck on as well , if the temperature of the engine does drop fuel use will increase

I'd agree with the faulty thermostat idea. You'll be able to tell whether the fan is stuck on by listening for it outside the car, but even if it was stuck on, the thermostat will still decide whether the coolant is circulated through the engine block or not. Having the engine running cold is hard on the oil as well as using more fuel, so it needs checking.

If temperature drops when driving and goes up when standing still - it is thermostat. And you should change it as soon as possible, as this has negative influence to engine and other systems. 

Agree. Dead thermostat. I fixed this on my 170 TDI DSG last year.

 

It is located on top of the gearbox.

 

Make sure you have the new model "splitter" with filter, so new dirt doesnt block your new thermostat.

 

Edited 1 April, 201511 yr by KMDTHY

ok many thanks for the quick responses . the car is more than due its variable service and I was about to book it in to align with the MOT but will now accelerate that  - simon

Agree. Dead thermostat. I fixed this on my 170 TDI DSG last year.

It is located on top of the gearbox.

Make sure you have the new model "splitter" with filter, so new dirt doesnt block your new thermostat.

Mine has same problem as op.

What is the part number of this splitter you mention?

Mine has same problem as op.

What is the part number of this splitter you mention?

1K0 121 087 AH - Splitter with filter

1K0 121 113 A - Thermostat

Edited 1 April, 201511 yr by KMDTHY

Thermostats are normally designed fail open so the engine can't overheat