A6 1.9 TDI 2001 - water temp gauge problem

[mkor]

I have read about the coolant temp gauge but I still do not know what the best starting point for my problem would be. Maybe if someone else reads the symptoms... Can you help?

The water temp indicator used to show 90 degrees nonstop till last week.

Day 0: in town, the gauge showing 60, in high traffic, lots of starts and stops, full sun. In the evening when driving to a shop - started showing 90 as usual.

Day 1: when I was driving on motorway, it was going down and up, between 60 and 80, but never reaching 90. Sometimes staying at 60 for long.

Day 2: when driving in the town, it was showing 90, fine, came back home, turned engine and the dash off, turned the dash on - no temperature at all (!), but it was just 15 second after it was showing 90. Ok, restarted the dash - 90deg as should be (!) and it was like that from now on - could not make it fail.

Day 3: driving in the town - 90, fine; went to fast 2 lane long stretch - temp going down to 60. Came home, the pipes were HOT, hardly could hold them, but when I was trying to make the gauge working by switching the dash on and off - no success.

OK, now I am confused - it sometimes looks like the thermostat, but on the other hand - the gauge started working when I restarted the dash... Is it the dash? Or maybe the connector or sender (but with touching nothing, started working?...)?

I do not know what to replace first, to nail it fast...

Any help appreciated,
mkor

[Padwick]

The sender goes on them. It's a common fault. I've just changed mine from the black type to the green one and they're pretty cheap (under a tenner). Just make sure you have a new clip (circlip type, can fly anywhere during removal) and o-ring when you're doing it. You'll also lose some coolant, so catch what comes out or have some more to top up if needed. Mine reads 85 or so now but has never fluctuated since.

I tried get a pic but it's not great as it's hard to get a camera in. It's on the rear left of the engine as you look in from the front. The green part with the black plug. The clip fits into the metal sleeve that the sender goes into (can be just made out).

[mkor]

Thanks a lot. I'll try during the weekend. Thanks for the photo - it makes it lot easier to find the thing.

[MikkiJayne]

Hmm this is interesting. Does it affect the V6 TDIs as well? Mine usually sits at 90 but occasionally drops to 60 for no good reason, then when I look at it 10 minutes later its back to 90...

[Padwick]

Well my mechanic told me the black sensor was a faulty part from day one and he was surprised it had never been caught on in 7 years of the cars life. If the same part is in the V6 then I presume it could be dodgy too.

[MikkiJayne]

Hmm well the sensor is the same on the V6, but I just checked and mine already has the green one so I guess thats not it.

Never mind

[mkor]

Problem solved. The sender replaced. It costed me 7.50 on eBay and now the gauge sticks to 90 all the time, as before. It was a little bit tricky to find it there and access it, but it's done now.

Thanks for all answers.