2012 Audi A7 Passenger Side Cat - How do I get at the top bolts?

[Valpo A7]

So I am trying to put the cat converter back in my 3.0 A7.

I broke the flange off so getting it out was fairly easy as i had clean and unobstructed access to all 3 flange nuts since the cat was out. Now I am trying to get it back in the car and having no luck. The cat is back up and in and on the 3 manifold studs. The bottom and top outside nut was decent access but I am trying to figure out how to access the top inner nut, the one closest to the block/trans.


Anyone have an idea on what has to come off the car/engine to get access to this?

A6/7 videos seem to be non-existent. 2016 S4 3.0 videos are available but don't really go into great detail on how to access that 3rd nut.

[Valpo A7]

Any thoughts?

[gk1]

I only have instructions on a Q5/SQ5. I don't know if that will help you though. Sorry.
Remove the tower brace.
Remove the Oxygen Sensor 2 after Catalytic Converter -G131-
Remove the plenum chamber bulkhead
Remove the left front muffler
Remove the left front wheel.
Remove the drive axle cover -1- in the left wheel housing
Remove the bolts -arrows- and the left drive axle heat shield.
Vehicles with selector lever cable heat shield: remove the bolts -arrows- and remove the heat shield.
Remove selector lever cable ball socket -1- from selector shaft lever with Pry Lever - 80-200- .
Press the securing clips -2- off and remove the selector lever cable from the transmission.
Then you can...Remove the nuts -arrows- and bolt -1- and remove the left catalytic converter from the exhaust manifold.
I assume install is reverse of that.

[Valpo A7]

Yeah the Erwin book says to remove the plenum bulkhead which means you have to take off the strut tower brace but pretty much not much else. The Erwin is very vague about repairs for the car.

I have the old out and repaired then back up and in the car. I can only get to 2 of the bolts from below. There is a whole other list of items to remove for the DSG trans that is listed as well. I am not sure how much more room I can free up if I take the secondary air pump off that size like it says for the DSG.

[430hps4]

With a combination of long enough extensions, look at the manifold from further back, near the main driveshaft. I think I used 3-4 12" extensions and was able to get to that one.

[AudiC7Owners]

This might help you

https://www.youtube.com/watch?v=ak6DtXfY7SU

[Valpo A7]

With a combination of long enough extensions, look at the manifold from further back, near the main driveshaft. I think I used 3-4 12" extensions and was able to get to that one.

Ill give that a try and see what I can see.

KwikStix, thanks for the vid, I had seen that before. I swear that makes it look like there is sooooo much more room than I have on the A7.

[AudiC7Owners]

Ill give that a try and see what I can see.

KwikStix, thanks for the vid, I had seen that before. I swear that makes it look like there is sooooo much more room than I have on the A7.Yea he has all the covers off. I would imagine there is slightly more room on the A7 have you seen JHM's video about the ratchet strap?

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[Valpo A7]

Yep saw the ratchet strap.

Right now I have the tail sagged completely and I took the bolt out of the bracket to hold the coolant hose that comes around the trans. Those 2 items there give enough room to easily slide the cat in and out without the need to cut off the bottom flange. I have the cat up in place and the bottom and outside nut on loosely. I have the plenum chamber bulkhead out of the car as well. THAT gave me the space I need to get a trouble mirror in to see the damned thing. Getting to that top inside nut is the only thing holding me up at this point.

[AudiC7Owners]

Yep saw the ratchet strap.

Right now I have the tail sagged completely and I took the bolt out of the bracket to hold the coolant hose that comes around the trans. Those 2 items there give enough room to easily slide the cat in and out without the need to cut off the bottom flange. I have the cat up in place and the bottom and outside nut on loosely. I have the plenum chamber bulkhead out of the car as well. THAT gave me the space I need to get a trouble mirror in to see the damned thing. Getting to that top inside nut is the only thing holding me up at this point.This is not making me feel great about doing my test pipe install lol. I'm gonna ask my tech what they do.

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[chydog]

https://www.ctsturbo.com/product/cts-turbo-b8-b8-5-3-0t-downpipe-removal-tool/

cts turbo markets this tool for likely the issue you are fighting

[Valpo A7]

Yup this GDMFing project has gone off the rails to be honest. I can only carve out weekends to work on it but thanks to Covid I get to work from home so I don’t exactly need the car right now.

I took the cowl bulkhead out and it created enough room to finally see that top nut and I was able to get a nut on it only to find out my threads are buggered up. Picked up a die and chased all the threads clean. Put it all together and started torquing nuts on. DAMMIT!!!! Stripped the bottom stud.

I put the car back together to move it over so we can get my wife’s car back in the garage with plans of tearing down this weekend. Picked up new studs with the hope that with PB blaster, heat, and patience I can get the stud out without breaking it off. If that happens I have to figure out how to remove the exhaust manifold.

Fuck me!!! I need more alcohol at this point.

[Alabama]

Yup this GDMFing project has gone off the rails to be honest. I can only carve out weekends to work on it but thanks to Covid I get to work from home so I don’t exactly need the car right now.

I took the cowl bulkhead out and it created enough room to finally see that top nut and I was able to get a nut on it only to find out my threads are buggered up. Picked up a die and chased all the threads clean. Put it all together and started torquing nuts on. DAMMIT!!!! Stripped the bottom stud.

I put the car back together to move it over so we can get my wife’s car back in the garage with plans of tearing down this weekend. Picked up new studs with the hope that with PB blaster, heat, and patience I can get the stud out without breaking it off. If that happens I have to figure out how to remove the exhaust manifold.

Fuck me!!! I need more alcohol at this point.

I apologize for smiling, but I'm always envious of you folk who can do this stuff; your challenges bring me back to Earth. As Bluto said in Animal House, "My advice to you is to start drinking heavily.”

[Valpo A7]

Hey at this point with this project there is nothing left but to laugh and smile at it.

[AudiC7Owners]

Yep... After attempting this I found out very fast that test pipes are not a DIY job. Good luck man. Best bet is to cut the oem cats out.

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[Valpo A7]

https://www.ctsturbo.com/product/cts-turbo-b8-b8-5-3-0t-downpipe-removal-tool/

cts turbo markets this tool for likely the issue you are fighting

This actually helps with access to break the nut loose for the downpipe that attaches to the cat converter. I am fighting with the nuts at the front end of the converter that attach the cat to exhaust manifold.

But at $40 I would not recommend it to be honest. For the same price you can buy a full set of crows feet sockets from Amazon.

https://www.amazon.com/Neiko-03324A-Metric-Crowfoot-Wrench/dp/B000N7DHFK/ref=sr_1_8?dchild=1&gclid=Cj0KCQiAst2BBhDJARIsAGo2ldVHDaP8B4jTLEaUqJ_O znp1Z255MLz05iqAZfR_gTz-WKkE245m8rEaAi-AEALw_wcB&hvadid=153714571854&hvdev=c&hvlocphy=9016213&hvnetw=g&hvqmt=e&hvrand=3941686210382327665&hvtargid=kwd-3673097956&hydadcr=1638_9515723&keywords=crows+foot+wrench+set&qid=1614263460&sr=8-8&tag=googhydr-20.

I needed a 22mm to break the O2 sensor free in the top of the cat.

Always cheaper in the long run to buy sets.

[Valpo A7]

Yep... After attempting this I found out very fast that test pipes are not a DIY job. Good luck man. Best bet is to cut the oem cats out.

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If you can get the nuts broke free for the cat to manifold the whole cat converter will slide out fairly easily on the passenger side. Take the trans mount off and sag the tail of the trans to create room. There is a metal coolant pipe that comes down around the trans on the passenger side and goes to the trans cooler, take the mounting bolt out and the pipe will move over just enough to remove the converter in 1 piece.

[Valpo A7]

This project took some time since I was learning as I went and only had some weekends to work on it, but I am finally done. Thanks to all that offered help.

Wound up stripping / cross threading the converter to manifold bolts and had to extract them and replace all three only to turn around and cross thread 2 of the brand new studs. The stock self locking nuts are the devil.

If there is any interest I can write up a DIY for this and post.

[sepheroth86]

I think that a DIY would be helpful for those looking to swap/gut cats and or install test pipes. [up]

Happy to hear that you FINALLY got the car back together man. I feel as if you have been working on it for a long time.

[gkott78]

I think that a DIY would be helpful for those looking to swap/gut cats and or install test pipes. [up]

Happy to hear that you FINALLY got the car back together man. I feel as if you have been working on it for a long time.

My DYI is simple... open wallet and pay shop... I have no interest in attempting this myself at all. Getting my test pipes installed next week, so I'll report back on what they say. They quote 1500 for S4's, but said mine being an A6 there should be more room to work with so it will most likely be less.

[sepheroth86]

My DYI is simple... open wallet and pay shop... I have no interest in attempting this myself at all. Getting my test pipes installed next week, so I'll report back on what they say. They quote 1500 for S4's, but said mine being an A6 there should be more room to work with so it will most likely be less.

lol

Are your current cats melted down? I would potentially be interested in them for gutting and swap purposes. I suspect mine have been failing since I bought the car. Tuning it last year didn't do them any favors.

[gkott78]

lol

Are your current cats melted down? I would potentially be interested in them for gutting and swap purposes. I suspect mine have been failing since I bought the car. Tuning it last year didn't do them any favors.

I'm suspecting they are based on what I smelled the other day doing 1/4 hits for logging.... Lets just say I don't think the passenger side survived.....

[Valpo A7]

My DYI is simple... open wallet and pay shop... I have no interest in attempting this myself at all. Getting my test pipes installed next week, so I'll report back on what they say. They quote 1500 for S4's, but said mine being an A6 there should be more room to work with so it will most likely be less.


OHHHHH TRUST ME. That thought went through my mind. I had a quote for $700 for labor for just the passenger side from an Audi tech as a side job for him. And that was without having to deal with the screwed up studs.

3.0 cats for the A6/7 are about $400 - 700 each aftermarket and about $1,000 new from the dealer.

As for room, there is a video out there to show how to do this on the S4 it looks like the S4 has more room to what I had.

[gkott78]

OHHHHH TRUST ME. That thought went through my mind. I had a quote for $700 for labor for just the passenger side from an Audi tech as a side job for him. And that was without having to deal with the screwed up studs.

3.0 cats for the A6/7 are about $400 - 700 each aftermarket and about $1,000 new from the dealer.

As for room, there is a video out there to show how to do this on the S4 it looks like the S4 has more room to what I had.

That's a troubling thought, I figured the s4 would be way tighter. I'll let you know what my shop has to say, I drop it off over the weekend and due to workload they are saying hopefully back by next Friday. I'll also let you know what I paid.

[GID]

This project took some time since I was learning as I went and only had some weekends to work on it, but I am finally done. Thanks to all that offered help.

Wound up stripping / cross threading the converter to manifold bolts and had to extract them and replace all three only to turn around and cross thread 2 of the brand new studs. The stock self locking nuts are the devil.

If there is any interest I can write up a DIY for this and post.

I realize this is a very old post, but did you ever do a DIY for this? Thoughts on how much room you had to work with compared to the S4 videos floating around on youtube? Potentially going to be attempting this on my A7 soon.

Thanks!

[Valpo A7]

I will add some notes to this thread tomorrow from my work computer. On my phone right now

[Valpo A7]

Working from a year old memory here so . . . .


Engine Bay Removal Work
Remove cowl cover
Remove strut tower brace
Remove plenum chamber bulkhead
Remove O2 sensor, I left mine plugged in. 22 MM crows foot worked great and gave me great leverage. You can buy a socket with 1 wall cut out to help with the wire but those tend to flex way too easy and slip.
Remove the upper 2 exhaust nuts. Inner towards the engine is a real pain in the Nixon. You will need 18 - 24 inches of extensions. 1/4 inch drive works better as they are lighter. Trouble mirror works good to see what the eff you are doing. If your flange broke off like mine and many others did you can do this from under the car as well.

Underside of car
Raise and support the front end of the car.
Remove the back belly pan and cross brace.
Remove the flex pipe. Buy a new gasket for the flex to cat flange and get a box or 2 of nuts. 2 boxes if you are doing both sides. I opted for generic nuts from Advance Auto as they install easier than OEM nuts.
Support the trans tail and remove the trans bracket.
Remove the bolt from the clamp holding the coolant pipe that comes around the passenger side of the trans. This gives you that last crucial 1/2 inch of clearance to get the cat out.
Remove the bolt holding the cat in place on its side.
Remove the exhaust manifold nuts. You will need 3 to 4 feet of extensions to reach, a universal swivel joint helps since you are working at a slight angle. You will need deep-well sockets. I have my universals wrapped in tape to help stiffen the joint otherwise they flop over too far. This way I can better control the socket.
Once all is loose then the cat should just about slide out, try not to drop it on your face.

For the driver side the book lists it fairly close to the same but you will have the steering linkage in your way as well. When you take the plenum manifold bulkhead out you will need to open the coolant lines to the heater core so get a set of hose clamps and means to plug off ports to minimize spill. You may or may not need to top off coolant when done.

Install in reverse order. Get a new gasket for the cat to exhaust manifold connection.


1 problem that I ran into was that I stripped the exhaust studs and had to buy a stud extractor from Autozone for about $20.

Dealer will have gaskets, usually replacement studs, and replacement nuts. Auto parts store will have all this at a better price and it will work just as good. I was actually able to get a Mehle gasket from Advance.

Harbor Freight sells an extension kit with enough extensions to do the job for about $20 for either 3/8" or 1/4". I picked up an inexpensive set of 1/4" deep well sockets from them as well. They are inexpensive but good quality for a home mechanic. I recommend an inch pound torque wrench for this as well. Harbor Freight carries a low cost but quality unit that is 1/4 inch drive.

Deep-well sockets will be needed as the stud sticks through the nut farther than a standard socket will allow to be used on. A problem I had was dropping the nuts all the time since I was working so far out on extensions or I would bump it wrong and shove the nut too deep into the socket to even start the threads. I wound up stuffing paper towel in my socket to remove the space and I would put a dab of grease on the nut to help it stick to the socket and help reduce dropping it. The grease will burn off in just a few minutes as things heated up.

[Gustaf]

A couple of additional tips to Valpo's great write up:
-when trying to get the cat-to-manifold nuts off, heat them up with a MAP gas torch and then give a shot of PB Blaster. I tried just going at them before I did this and felt like I was going to break the stud. Once I did heated and then hit with PB Blaster, they all came off very easliy. Note, I'm in the northeast and the car had obviously been used during the winters so things were a little more corroded than something that has lived its life out on the west coast.
-while u-joints are great I feel that wobble extensions are a bit better as you have a bit less of a chance of slipping off the nut and messing it up