2000 A6 2.8 flex pipe update
 

Well im all done and i have to tell you this project is NOT for the faint of heart .. this has been done many many times before so just tought i would add my experience for future searches . ( car has 350,000km )

1. Both flex pipes rotted out on my 2000 2.8 litre. Found it ultimatley to be casused by resonator hangers rusted right off the heatshield , hangers were still in the rubber so managed to get them welded back on. all the weight had transfered to the flex pipes so with age rust and weight they just tore open.

2. bought the flex pieces from ECS , cut off the excess pipe on one end of the new flex pipe and had it tig welded to the cat ( coz the cats could come right off now once the sleeves were cut off ( totally rusted clamps and bolts ) .

3. Removed the down pipes .. ( this was a bit of a nightmare .. do yourself a favour with the car on jack stands and remove the two front wheels , makes it way easier to get to the lower nuts on the downpipe to manifold..

drivers is fairly easy with access to the top nut . pasenger is an absolute nightmare and you wil have to remove air filter box and have to fight for every millimeter trying to get a wrench on underneath the the combi valve but i did get it eventually with lots of breaks and swear words .. definitely needed quarter drive with 13mm socket with a very short extention . aslo have to move fuel lines and hoses ..

to get the pipes off you have to pull them down and rotate 180 degrees to get the precat out of the hole between the engine and body.

4. old weld ground off down pipes .. dont cut if you can as you dont have a lot to play with as there is a bracket and bend right at the flex pipe on the drivers side.

5. Put downpipes back in place and tighten in place with regular 13mm nuts ( id did 2 out of three on each side and made sure it didnt move ) .. do not use the exhaust ones you took off as they are antivibration ones with the end deformed .. the are just a pain and not needed for this step . will just make it a pain to put on and take off.

6. Once down pipes are in place and solid put your cats on with your new flex, cut what you need to fit and remember you have a coupler at the back so it is not critical . i left about a half inch where the sleeve coupler goes .. tack weld the downpipe to the new flex pipe with everything on place and your cat bottom horizontal to the ground.

7. take off your temporary 13mm nuts you put on the downpipe so you can lower the whole assembly about a foot .. then weld it all the way around tacking back and forth to get a good weld . gas welding is nice but wahtever you have i guess.

8. put your new gaskets on your downpipe to exhaust manifold ( autohausaz ). tighten up with your correct exhaust nuts now ( i had some coppper ones left over from my 911 .. very nice ) and put on your new coupling sleeves (autohaus )


Additional notes ...

you dont have to completely remove your downpipes to grind them off but do it . it is WAY easier .. cant grind so close to the body and if you have them off the exhasust manifold you are 99 percent there .

Doing on a car lift is preferable obviously but can be done on jackstands.. when you tack on the flex to the downpipe it is way longer so can not be removed again , has to be welded under the car ( due to the 180 roatetion and it is now about 4 feet long. ) with a lift you could easily tack completely remove and do a much nicer job.

doing oxygen sensors can be done at this time and even though i had O2 sensor codes I decided against it . This is because of the torn flexes not sure how must was due to air coming in here .. will wait and see.

DEFINITELY want to do rear propshaft nose seal while doing this. the cats and exhast have to be removed to do this seal and once the cats are off it is right there , i had it all off anyway ,, lots of writeups on this and cost me 70 dollars total and that was with the ridculous Audi 40.00 gear oil for one quart. Was pretty painless.

This car is NOT my daily driver so i vould take my time . if your is and time is an issue take your flexes to a muffler shop and just pay them a couple of hundred bucks to do it and your done . well worth the money .. for me it was about the challenge