B8 A4 DIY: Catalytic Converter Removal & HFC or Test Pipe Install

[magicmarker]

I just got that 4th nut off the turbo. Couple of things that helped me:

- use 1/2" socket, 10" extension and 2' breaker bar (3/8 had too much give)
- I stayed away from swivel: too hard to guide onto nut and too much give
- go in from the top and my pinky could just reach around cat and guide socket on
- use a mirror to check fit on nut
- I stayed away from deep socket, again too much give and chance to tilt
- used 12pt socket to get as much room for torque as possible

Hope that helps. After I broke it free with breaker then I switched to rachet to speed up removal

[Scrap123]

Removing a catalytic converter seems to be a very complicated thing.
If you remove it badly it is possible to lose the PGM inside?
https://www.catalyticconverterrecycl...ytic-converter

[604AR]

I just installed my HFC thanks to everyone's tips and tricks. The problem nut I had was third hidden bolt on the downpipe side. I took it off with a ratcheting wrench but the new HFC lacked the clearance to fit a ratcheting wrench. I had to multiple extensions and Swivel with a thin walled socket to put it on. I found it easier to remove the downpipe/midsection so that I could remove the cat from the bottom. I couldn't get it to fit coming through the engine bay.

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[604AR]

Removing a catalytic converter seems to be a very complicated thing.
If you remove it badly it is possible to lose the PGM inside?
https://www.catalyticconverterrecycl...ytic-converter

I don't think it's possible to lose the precious metals from your catalytic from changing it.

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[Theiceman]

It's not that complicated to replace. Once you realize it's a lot easier to remove the cat from the down pipe outside of the car it's not too bad.

Cat material is pretty robust

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[jaustin]

My downpipe bolts are shot. Can I cut the back sides off and tap out or cut the nuts and tap out? Obviously I can see the backsides so that will be easy just not sure it will turn out to be the easiest.

[Belo]

hey Dan_q awesome step by step, can you post a link to where you bought your high flow cat from and also did you need to use a spacer ( so the check engine light does not come on ) on both and top and bottom or just the bottom and also what kinda spacer you used. thanks!!

[ekinchheng]

I just did mines over the weekend. The down pipe bolts were pretty rusted and I ended up bending the flange in the process of separating the down pipe from the cat. I ended upgrading to a new downpipe (Becker Turbo) without the resonator.

[Grouch]

hey Dan_q awesome step by step, can you post a link to where you bought your high flow cat from and also did you need to use a spacer ( so the check engine light does not come on ) on both and top and bottom or just the bottom and also what kinda spacer you used. thanks!!

Two most popular HFC seems like the 034 and Eurocode. You need a spacer for sure if you're not going to get a tune that codes it out. All spacers are a hit or miss for everyone. What works for a lot people here has not worked for me at all. You only need a spacer for the rear 02 sensor, not the front closest to the turbo.

[Ark88]

Other than it a rear o2 sensor CEL being annoying and concerning for passing emissions, is there an impact on the performance and longevity of the engine?

[A4x]

Other than it a rear o2 sensor CEL being annoying and concerning for passing emissions, is there an impact on the performance and longevity of the engine?

No. If anything, it is healthier for the engine to run a HFC. Less restriction and heat.

[Ark88]

Game on, thank you.

[Ark88]

So finally got the HFC installed. That was no joke. But I am left wondering about the spring mount. I had such a difficult time getting the bolt back through with the aftermarket HFC. I had to use a wire and have someone pull from the outside just to align the bolt through the screw. Should it be that difficult? If it is on can it be to tight and cause damage due to excess load on the spring mount? Have most of you with an After market HFC re-installed the spring bolt to mount?HFC spring mount.jpg

[BMWManiac]

So finally got the HFC installed. That was no joke. But I am left wondering about the spring mount. I had such a difficult time getting the bolt back through with the aftermarket HFC. I had to use a wire and have someone pull from the outside just to align the bolt through the screw. Should it be that difficult? If it is on can it be to tight and cause damage due to excess load on the spring mount? Have most of you with an After market HFC re-installed the spring bolt to mount?

While the entire process was somewhat difficult, most of the difficulty for me was removing that lower 15mm nut and then removing the entire cat itself. I think I might have had some trouble with the spring, but I don't recall it being a pain. If you got it snugged down, then you're fine. It was what a 10mm? I don't think there is much load on it

[Ark88]

I added a picture. What do you think about the side with the rubber insulator. I was concerned with the amount of tension there as well as on the HFC joint itself.

[Iceman502]

I added a picture. What do you think about the side with the rubber insulator. I was concerned with the amount of tension there as well as on the HFC joint itself.

When you tightened the spring mount, was the exhaust clamp connecting the resonator already snugged down? If it was, that might explain why aligning the spring mount was so challenging. I don't know much about the USP HFC, but I can say the IE version had no issues with that.

[Ark88]

Yes, when I connected the Spring mount I had everything pretty much tightened down. That may have been the issue one I thought of as well. I already snapped one stud trying to loosen the new nuts i tightened to the studs so I would do anything I can to avoid removing or loosing anything connecting the HFC at this point. Being the spring is on as difficult as it was, would anyone feel it could be a concern for the connecting pieces. I mean how essential is that spring mount, does anyone go without when they upgrade.

[Iceman502]

Yes, when I connected the Spring mount I had everything pretty much tightened down. That may have been the issue one I thought of as well. I already snapped one stud trying to loosen the new nuts i tightened to the studs so I would do anything I can to avoid removing or loosing anything connecting the HFC at this point. Being the spring is on as difficult as it was, would anyone feel it could be a concern for the connecting pieces. I mean how essential is that spring mount, does anyone go without when they upgrade.

Youch, so the cat is only connected with (3) studs now? I'd be more concerned about an exhaust leak now than spring mount tension. I've never heard of anyone running without it, and I think its main purpose is to dampen vibration in the exhaust system. Losing it would also put more weight on the turbo exhaust outlet and remaining (3) studs.

[D_a3]

Not a one. Feb will be two years.

Which spacer did you use.. if you dont mind me asking

[wilmar13]

After removing air-box and making sure I could loosen the 3 easily accessible nuts, I tried like mad to get that 4th nut off (lower engine side) at turbo, but just couldn't do it. I probably spent 2hr straining muscles in various contortions from above and below with various extensions and swivels. At one point I had solid bite and was able to get a 2 foot pipe on the wrench for more than 3' of leverage, nothing budged, but it was hard to really tell where the forces were going. I felt that either the stud was going to break (I'll take it!), or the nut was going to strip or stud would get bent (which would really suck).

I walked away from it, then came back and noticed if the vacuum pump was removed it would make it so much easier to get to. I have never removed it and the HP fuel pump and hard lines were kind of intimidating, but after a bit more straining, I decided to go for it. It really wasn't hard to do and with the vacuum pump off the access is so much better. The nut broke free with a 3/8" ratchet. I didn't even need to get under car, the mid-pipe bolts are easily reached from the top directly with long extension and there is enough flex I was able to lift cat out the top with no issues. It was easy. I really think in hindsight the time it takes to remove vacuum pump to free up a lot of space and get the lines out of the way to remove need to get under car is a good investment if you have any issues with that problem nut/stud, and perhaps even if you don't.

[Kloverdale]

Just did this job and it wasn’t as bad as I thought it would be, to get the 4th pita nut off the turbo I used a 3/8 ratchet with a 10” extension and a 15mm deep socket. I used my left hand underneath the cat to guide the socket on to the nut. Then used a piece of 1” pipe cut to about 18” to use as a cheater bar on the ratchet. It came off real easy. The rest of the job was a pain on my back with the car on Jack stands. But totally worth it. I installed the IE down pipe and mid pipe with IE stage 2

[thefleshrocket]

I was able to get the fourth nut (sort of) off of the turbo without too much difficulty, using a 3/8" ratchet, a 6" and a 3" extension, and a 15mm deep socket. The first problem was that the nut pulled out the stud. I figured, just leave the nut on the stud, since it's on there so snugly, and just thread it back in when installing the HFC. I got a couple of turns (I think) finger-tight, then switched to my socket. It was almost immediately very hard to turn. I gave it a bit more effort and it barely moved, so I backed out the stud. Sure enough, it looks like it started to cross-thread. Not sure how the hell that happened. I tried threading a nut onto the stud, and it doesn't want to go, so the stud is definitely not in its happy place.

What can I do? Can I buy another stud? If so, how do I install it? Do I just finger-tight it, then thread on the nut and make it tight?

Or do I just buy a bolt and washer and hope that works?

Or am I really boned, and it's time to order a K04? LOL :(

[thefleshrocket]

What can I do? Can I buy another stud? If so, how do I install it? Do I just finger-tight it, then thread on the nut and make it tight?

Or do I just buy a bolt and washer and hope that works?

Or am I really boned, and it's time to order a K04? LOL :(

I ordered a stud and nut from the local VW dealer--will arrive tomorrow. I also picked up a bolt from the local auto parts store. I think I figured out how to install the stud--put two nuts on the stud, lock them together, and use that to tighten the stud into the turbo.

[GripB85]

I'm installing a new turbo and need help reinstalling that bottom motor-side nut on the cat to turbo flange. I'm reinstalling the stock converter. Any tricks to starting the nut on the stud? I can't reach the stud with my fingers at all. I'm afraid if I try to put the nut into a socket and start it by using the same method as I removed it (extensions and swivels reaching down by firewall from top of engine) I'll just cross thread it.

[StuckAntichris]

You should be fine to use the socket to start the nut, just line it up and spin it backwards until you feel the threads "jump" then you should be able to thread it on clockwise. There are many ways to keep the nut in the socket but a bit of paper towel, duct tape, etc. should be fine.

[GripB85]

Thanks I'll try that

[GripB85]

It's impossible. Trying to line up a loaded socket with a nut in it, blind, where it has u-joints and extensions, and get it aligned enough to start on the stud is infuriating. The socket just falls down. There's no space to fit my hand in to hold it up. Plus I'm kneeling on the engine with one arm down by the firewall and couldn't possibly reach the end I need to hold even if my hands were small enough.

When I removed it, nothing was lined up perfectly, it was just "close enough" to get some bite and loosen. There's gotta be a trick to doing this easier.

[tedtracy3]

Wrap some tape around the u-joint so that it isn't so floppy but it will still allow some flex.