WITW - Andrew's Irish Green

[MikkiJayne]

I'm planning just pads as there are no unpleasant noises at startup. With just over 100K and nice and clean inside I'm expecting the gauze filters to still be intact so the tensioners should be in good health

[MikkiJayne]

Proper work went badly today so I didn't get on to the tensioners. I got stuff ready for powdercoating instead.

All four springs are mostly in good condition, apart from the bottom coils which are all very rusty. This is the prime spot where they snap, so I will get these blasted and recoated which will hopefully stop any cracks forming and extend their lives.



The rear lower spring seat is also very crusty - these are NLA so need recovering



After chipping off the rust, these will go in the evaporust for a few days



Something on the front of the engine was howling, and I suspected the fan bearing as the usual culprit. Surprisingly that is fine and its actually both the alternator and AC compressor bearings making the noise. I stripped the alternator down to find the front bearing so worn it rattles, and the rear almost seized. The AC pulley bearing is very loose and crunchy. Very unusual for both of these to go at this mileage.



The slip ring and brushes are also very worn however thanks to Marcel I've discovered a source of replacement internal alternator parts so these will also be replaced

[HPsauce]

Interesting, so is that the source of the rev-linked whine you can/could hear in the cabin?

[MikkiJayne]

More of a whirring howl than a whine to my ears, but definitely related to engine speed yes. I found it particularly noticeable when cold, which is logical since the bearing clearances reduce when everything is hot. The alternator was particularly loud and likely responsible for the majority of the noise.

[Ronin]

Mmm I get the same noise with AC on only, my alternator is brand new so it must be the compressor bearing? Is that replaceable on the car? It sounds a bit like an owl stuck in hvac

[MikkiJayne]

If it switches on and off with the AC its usually the electric radiator fan, or compressor internals, since the pulley on the compressor runs all the time. The pulley can be removed from the compressor with the compressor still in the car so the bearing could be changed without opening the refrigerant circuit. I have one coming from the US which should be here on Friday, and Simply Bearings are looking in to getting some more

[MikkiJayne]

A healthy tensioner on bank 1 This is usually the first to fail so I am expecting bank 2 to also be fine.



Minimal tramlines, filter gauze intact



Quick brew before I fit the new pads



Sealant on the end cam cap



Done

[The_Laird]

Well, that wasn’t the usual scary story, was it? I recall that Stephen’s was an inch from terminal and mine wasn’t a lot better. It’s rare that we see a WITW instalment so straightforward. Here’s hoping it’s an omen!

[HPsauce]

Does the gauze come out if it's good, or do you leave them in?

[MikkiJayne]

It comes out because even if its still good now, eventually it won't be and then it kills the tensioners.

Its there to stop little bits of carbon or oil sludge which may build up post-filter from going through the tensioner, however those little bits of carbon (should there be any) would clog the gauze and then the oil pressure would just punch them through it. At that point both the carbon and the stainless steel wire go through the tensioner and destroy it. Overall, its preferable to keep the oil changed regularly and let any post-filter detritus just go through the tensioner.

This is fairly standard Audi M.O. and they are still doing it now. It killed a lot of W8 Passats because it was a £10K repair at the dealer. Ditto the W12 although more of them survived simply because the host vehicle was worth more at the time. Its also what kills the turbos in the 4.0TT. They have a gauze in the turbo oil feed to stop particles going through the turbos. Instead, the particles clog the filter and stop oil going through the turbos which kills them in short order. Another £10K repair. The US has a recall for it, presumably due to the threat of a class action suit, but Audi UK don't care and refuse to do anything about it or even contribute to repair costs.