S8 Starting
 

A couple of issues, other than cosmetic, have cropped up now I have been driving the S8 for a couple of days.

1. The temperature gauge is temperamental - sometimes it works sometimes it doesn't - I haven't noticed a pattern?

2. First start in the morning from cold (seems OK at other times) the engine catches and the revs rise then immediately die away and stalls - try with a little throttle and starts OK?

Any help or advice would be very much appreciated.

Neil

Could be faulty coolant temperature sensor that causes both issues.

I'd agree with that; based on my experiences get a genuine one from a VAG dealer not a cheap eBay version.
It's actually a dual sensor, the visible gauge and ECU signals come from separate components, so it can be quite confusing.

Fairly easy to change; I think I documented some tips in a thread somewhere on how to do it without losing small clips down the back of the engine, and not losing any coolant. ;)

Edit: All in this thread: http://forum.a8parts.co.uk/showthread.php?t=1157

I just tried changing mine last weekend. I read the quattroworld procedure, 5 minutes job my ar$e lol. The little bu@@er must be the original one from 16 years ago and its properly corroded in there, it would not budge. So I left it in for now.

http://forums.quattroworld.com/a8/msgs/39064.phtml

I am going to try anti-seize solution, namely a mix of around 70% vegetable oil from supermarket and 30% acetone (nail varnish remover). Its worked wonders on a few other things so far.
My only slight worry is the housing the temp sender is jammed into appears to be plastic I hope the small amount of acetone doesn't harm it.

So I don't want to scare you but be prepared for a fight :)
I hope your one is not corroded and easy to remove.

Yep, it's a pig to get out. And you have to be careful not to rotate it or snap off the plastic part too. It'll seem like it's not budging at first but eventually it pops out after a lot of wriggling and pulling.

More importantly, make sure when you fit the new one that the crappy plastic retaining clip is properly secured, if you don't want to end up on the hard shoulder like I did:
http://forum.a8parts.co.uk/showthread.php?t=9845

The clip on mine kept working loose, despite being fully locked into place. I'd recommend putting some heatshrink sleeving over it just in case like this.

Another thing to bear in mind is that though it "should" be easy to wiggle out, once the clip is removed, with the engine cold the reduced pressure might create a bit of suction.
So worth undoing then reclosing the coolant filler cap first to equalise pressures. Or if you have an assistant (glamorous or otherwise) get them to open the cap slightly and be ready to close it again very quickly as soon as the sensor gets moving.

Thanks guys good tips +++

I wriggled it side to side and all around for a long time no budge at all. I can see the corrosion around the edge, its properly baked in.
I did not dear apply too much force with the pliers in case i broke off the green part.

Definitely need to use some anti-seize on this one I think.

It's not a tight fit in the housing when clean, it's the rubber seal and plastic clip that really secure it.
Might be worth scraping gently around the edge, maybe use some descaling chemicals?

Thanks
 

Marvelous - thanks for all the advice, very much appreciated!