D3 3.0 tdi temp gauge / heaters issue

Bushido · #1 25th November 2019, 08:31 PM

Long and short folks ...

Temp gauge often sits at 70 degrees on runs. Will rise occasionally to 90 when sat in slow traffic / stationary. Cabin heaters are typically warm enough to take chill out but no more. Are hotter when gauge is sat at 90.

Replaced the thermostat and coolant temp sensor up to now with oem parts. No difference.

Where do we go next please? In dependent suggested back flush of coolant system.

Any advice appreciated

snapdragon · #2 26th November 2019, 02:38 AM

https://www.ebay.co.uk/sch/i.html?_f...21113&_sacat=0

You need to replace this, it is beside the gearbox inline with the coolant hoses. Taking off the wheel makes it easier. Might be easier to buy one and get a fast fit place fit it, it is easy enough but almost in the middle of the car is difficult when laid on the floor.. It is just undertrays, two spring clips and some spare coolant to top up. I went with a FEBI one and it has lasted longer than the original VW/Audi one.
I don't know who supplies them but they are a common failure across many VAG models.

Johnmed · #3 26th November 2019, 09:55 AM

Snap beat me to it. It’s the often overlooked/largely unknown thermostat.

Bushido · #4 27th November 2019, 06:15 PM

Much appreciated, I tried an indi and our sponsors regarding this who all seemed to think I had dreamt up the existence of it...

Will report back

Bushido · #5 10th December 2020, 08:23 PM

And just a year later I finally got around to having it replaced!! lol
Fingers crossed it does seem to have done the trick but will know better when I run to work in the morning. Wish me luck!

Bushido · #6 12th December 2020, 10:15 AM

Job jobbed. Temp gauge sits at 90 and we have..... heat in the whole cabin!!!

Still have the garages I approached saying "cant have been that..."

Johnmed · #7 14th December 2020, 08:22 PM

Quote:

Originally Posted by Bushido

And just a year later I finally got around to having it replaced!! lol
Fingers crossed it does seem to have done the trick but will know better when I run to work in the morning. Wish me luck!

Best not to rush into these things, eh!!

Bushido · #8 6th December 2021, 07:02 PM

And now we are going the exact same route with the latest 4.2 tdi!

See if I can do it in under a year this time though

Bushido · #9 19th December 2021, 09:02 PM

Well b#gger me!

We replaced the valve. No improvement.

Was suggested to replace the engine coolant temp sensor for the sake of £16 and 10 minutes time. No improvement! (top tip - but the little plastic circlip at the same time as the senor. Its £2 well spent!!)

Is the irony here that I am now looking at the thermostat (the route that I went with the 3.0 before finding out about the little valve under the gearbox

)

The symptoms are that the car is very slow to warm up. The gauge remains on 50 for a good 10 minutes (+). It will eventually creep up to 70. If out on a longer run of 30 mins or so with a bit of traffic it will sit just below 90.

Interestingly, even when just over 50 I can still get enough heat into the cabin to at least take the chill off. And at 70 it will happily warm the cabin.

Any thoughts welcomed

ainarssems · #10 20th December 2021, 04:44 AM

Check radiator/hoses going to it. If they are warm when engine is showing 50C then thermostat is open and letting coolant to the radiator when it should not . If rad/hoses cold then it's something else.

Is the auxiliary Webasto heater working? 10 min to 50C does not seem that unreasonable in this cold weather if the aux heater is not working.