D2 down pipe removal

[jamesb]

Just when I think I am going to get a few weeks hassle free motoring - the A8 fails its MOT because one of the exhaust flexi joints has split.

Cant be too mad, thats not bad going for a 21 year old exhaust.

I am thinking about removing the down pipe section, removing the old flexi and welding in a new flexi.

Checking the workshop manual it appears if I take the front wheels off I should be able to access the bolts holding the down pipe to the manifold? Can anyone confirm if thats right?

Thanks

James

[strummagnet]

Might be best to confirm what engine size and configuration you are working on........

And whether it is nearside or offside. Could make all the difference.

[MikkiJayne]

Engine, year, and side definitely make a significant difference, from 'piece of cake' to 'oh hell no!'.

[jamesb]

Hey, sorry forgot the important part.

Its an AKC, 3.7 V8 Quattro. I get the feeling its a hell no, based on what I can see from a quick crawl underneath.

Does anyone make these parts as replacements?

[MikkiJayne]

An AKC isn't too terrible. The main challenge will be getting the upper cats through the gap between gearbox and tunnel. It is aided considerably by removing the primary O2 sensor, although that in itself is a bit of an ordeal since the SAI valve is in the way. It may be necessary to drop the rear of the subframe a little to gain clearance for the upper cat.

The left hand one could be done on jack stands as it is quite short and splits halfway down. The right hand one will need a lift though as it is one piece from manifold to exhaust system and needs 3-4 feet of ground clearance under the car to come out.

I'm not aware of anyone in the UK making replacements for the V8 unfortunately.

[jamesb]

Thanks for the advice. Ground clearance will be a big issue as I dont have a lift and chucking it in the garage will just result in a hefty bill. From my limited poke around underneath access looks like a complete arse along with rusty bolts!

Been mulling this over on how to get the flexi changed without disturbing the down pipe - so just sounding out the idea for comments.

Cut the flexi off at the down pipe end

Drop remaining flexi with cat.

Cut the flexi off the cat.

Weld new flexi onto cat (now I can get the mig all the way around)

Weld slip collar onto flexi (may even come with one).

Offer up cat & flexi section.

Slide slip collar over down pipe and clamp in place.


Seems achievable but wont know until I start. Whole exhaust will probably fall apart after that!

[MikkiJayne]

Assuming you're talking about the right hand side, you're not going to get away without welding the downpipe unfortunately. If memory serves, it is curved right up until the point where it goes in to the flexi, so no straight section long enough to fit a slip joint.

What may be more feasible is to get hold of a pair of 3-bolt flanges (ideally get a left downpipe gasket copied and laser-cut in 8 or 10mm steel) which you can then weld on to the right hand downpipe before the flexi. If you get the flange sized so that it fits over the downpipe you can then mig it from the inside, which is much easier to get to. Then, continue with your plan but also weld a flange on to the new flexi, essentially replicating the left hand side.

I do have some 3.7 downpipes cut at the flexis in the workshop. If I remember tomorrow I'll grab a pic of them

[Fredde]

Originally Posted by MikkiJayne

Assuming you're talking about the right hand side, you're not going to get away without welding the downpipe unfortunately. If memory serves, it is curved right up until the point where it goes in to the flexi, so no straight section long enough to fit a slip joint.

What may be more feasible is to get hold of a pair of 3-bolt flanges (ideally get a left downpipe gasket copied and laser-cut in 8 or 10mm steel) which you can then weld on to the right hand downpipe before the flexi. If you get the flange sized so that it fits over the downpipe you can then mig it from the inside, which is much easier to get to. Then, continue with your plan but also weld a flange on to the new flexi, essentially replicating the left hand side.

I do have some 3.7 downpipes cut at the flexis in the workshop. If I remember tomorrow I'll grab a pic of them

This is exactly what I did when my cats were stolen. Worked really well and prevented further issues since now the downpipes have flanges before the cats making the exhaust much more service friendly. Shoulda been like this from factory imo.