Funnily enough I've done that a few times and IIRC it wasn't that difficult provided you take a few precautions, including:
1. Make sure the engine is stone cold
2. Leave the coolant filler cap on tight so no coolant flows out when you remove the sender
3. Take EXTREME precautions not to lose the retaining clip - I think I used string on a stiff stick tied to it to ensure it didn't get lost
4. Make sure you get a new O-ring and ideally a retaining clip with your new sender.

I think I used the same "string on a stick" to manipulate the retaining clip back in on refitting and also may have released the coolant cap slightly as I pushed the new sender in so there was no back pressure. It might need a gentle tap to get it seated down properly. You'll know if it's not down far enough as the clip won't go in.

I also noted MJs earlier comment and can confirm that certainly in my case it's exactly that, the debris builds up above the relatively small holes that lead down into those drains. Over the years I've found disturbing and syphoning assisted with hot water and detergent generally gets it flushed through.

Hey Mikki what's your fix for the battery junction? Do you just replace it with the same part?

Yeah surprisingly that is still available - 4D0971828, 7 left in the UK for about £10.

When they run out I'll probably start printing them in nylon, but no need at the moment as I have a box of them.

A bit quiet this week as I've been waiting for parts and working on another engine. Mike came over on Thursday and gave me a hand with the cam chain tensioners, and I completely forgot to take any pictures, but thats well documented elsewhere anyway.

However, dismantling a 130K engine with still-working tensioners has proved instructive. Both gauze filters in this one were still intact, as expected since the tensioners still worked:

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

Removing one of the tensioners I think I found not only the reason for the gauze filter in the first place, but also the reason for the filter failure and subsequent tensioner failure - carbon build-up from inside the oil galleries. I didn't get a pic, but underneath the gauze there were tiny chunks of the carbon found in the sump, cam covers etc. As the tensioners have rubber o-rings in them, I think Audi put these filters in to protect them from this carbon, whereas camshafts, crank bearings etc, being metal, wouldn't be affected. The problem though, is that the carbon will eventually accumulate behind this non-replaceable filter which then gets clogged and oil pressure just punches through it. The broken filter material then gets pushed through the tensioner and destroys it.

On balance, I'll take my chances putting the carbon through the tensioner rather than stainless steel mesh, and change the oil more often.

The tensioner pads were in remarkably good condition considering the mileage, but of course I replaced them since everything was in bits

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

An upside-down engine is oddly satisfying :D

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

Its considerably easier to replace the sump like this ;)

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

Another bonus of having the engine on the stand is that I can take the inlet manifold off with it upside down, thus ensuring none of this detritus falls down the inlet ports:

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

I have no idea why these engines collect so much grit in this area :Confused:

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

Grit removed, sump re-sealed, and back the right way up again. The usual sand and oil mess in here

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

Better +++

http://forum.a8parts.co.uk/attachmen...1&d=1601669105

Hopefully the engine will be complete tomorrow and I can get the gearbox service done on Sunday :)

Wow this is just amazing

I'll be running out of superlatives before long; I love this sort of real world documentation on our beloved D2s. Fascinating stuff. Cheers to all.

Agreed - like our own private (but much better!) online version of Wheeler Dealers +++.

Inlet manifold back on

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Oil cooler back on with an aluminium link pipe and new pressure sensor

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Water pipe and various bits back on the rear

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Ready for the the timing belt to go back on

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Water pump mounting surface cleaned up

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

I took the slightly unusual step of chasing out the threads with a tap, since the last water pump was stuck on with lots o silicone which had made its way in to the bolt holes, so that needed cleaning up and removing otherwise it could hydrolock the new bolts

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Water pump on with new bolts

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

New belt kit on

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

When we got it fired up originally, it was making a lot of noise from the hydro fan, which I thought was the coupling causing the fan to run at full speed, but when I took it off the coupling was fine. It turned out the noise was actually the fan bearing itself which is very loud and grumbly. Luckily I now have a sensibly priced solution to this

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

The fan mounting hub is bolted in to the bearing

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Pull the bearing off the hub

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Hub with the bearing removed

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Press the hub in to the new bearing

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Bolt back in and it runs nice and smooth again :)

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Back on the engine

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

That concludes all the engine work for which it needs to be on the stand so its back on the separating machine. I still need to reattach the coolant hoses, spark plugs & coil packs, ancilliaries, and then fit the replacement wiring harness but that'll happen when its reattached to the gearbox.

http://forum.a8parts.co.uk/attachmen...1&d=1601754943

Just love this +++

Me too :love: