Can the Exhaust Center Section Be Replaced in the Driveway or is a Lift Needed?

[Kolbenringe]

So I have to replace my center muffler due to rust and I have the lower type in this diagram: https://audi.7zap.com/en/rdw/audi+a4.../2/253-253090/
where the center section branches into two outlets then goes to two mufflers.

Does anyone know if this is something where I can maneuver everything while the car is jacked up or do I really need to put the car on a lift?

[Smac770]

You certainly don't need it on an over your head type lift. But you're going to need the car off the ground. It's certainly something I'd expect to be able to do with the car on my QuickJacks.

[Kolbenringe]

Thanks. I can get it off the ground with two jacks, but I don't really have the ability to do four jackstands or ramps in my building's garage. I guess I'll have to go to the hobby workshop where they rent out lifts by the hour.

Also curious is that this exhaust that I have is pretty difficult to source, as it's in very low supply at Audi and aftermarkets don't deal too much with it- it has the larger diameter pips and the two mufflers at the back as opposed to the straight through and then to one muffler setup that seems to be way more prevalent.

[Smac770]

I think trying to work with it on an unlevel vehicle might be hard, to work the alignment preload of the hangers and such since gravity will be at an awkward angle.

[Kolbenringe]

So my luck it's actually the front section's muffler, so that whole thing from the downpipe has to be replaced. The shop confused me because I also thought it was the front section muffler, but they kept calling it the middle.Now I have to see how feasible this repair will be on my own or if it will be full of complications.

[RockJGC]

You can do it with the back of the car on a set of ramps. The exhaust can be unbolted from the downpipe (just three nuts) from up top if they aren't too rusty and then you can still pull out the entire exhaust system from under the car if the back wheels are on a set of ramps. I've actually done exactly that to remove my OEM exhaust and install my AWE exhaust system.

[Kolbenringe]

You can do it with the back of the car on a set of ramps. The exhaust can be unbolted from the downpipe (just three nuts) from up top if they aren't too rusty and then you can still pull out the entire exhaust system from under the car if the back wheels are on a set of ramps. I've actually done exactly that to remove my OEM exhaust and install my AWE exhaust system.

You mean that front section with the flex coupler? I'm going to have to really inspect this whole thing because the shop told me it's the front and the center resonator. They seemed also pretty confused and then just ghosted, so I'll have to figure this out now. If it were possible, I'd cut the front resonator out and put a test pipe in for a few weeks, even though this is like the biggest no-no in Germany, but it would work for an upcoming trip. I could already soak the fasteners anyhow. Can this front section be pulled out without pulling the transmission support? I won't have a transmission support jack available.

I have ramps, but the building management will flip if I use them in my garage. We actually have a repair and wash area that I liberally use, but ramps can't be used there and jackstands are too unsafe (the ground is angled for drainage). So I'll just rent a repair bay for like 8 Euros an hour at the local DIY repair shop,

[RockJGC]

You mean that front section with the flex coupler? I'm going to have to really inspect this whole thing because the shop told me it's the front and the center resonator. They seemed also pretty confused and then just ghosted, so I'll have to figure this out now. If it were possible, I'd cut the front resonator out and put a test pipe in for a few weeks, even though this is like the biggest no-no in Germany, but it would work for an upcoming trip. I could already soak the fasteners anyhow. Can this front section be pulled out without pulling the transmission support? I won't have a transmission support jack available.

I have ramps, but the building management will flip if I use them in my garage. We actually have a repair and wash area that I liberally use, but ramps can't be used there and jackstands are too unsafe (the ground is angled for drainage). So I'll just rent a repair bay for like 8 Euros an hour at the local DIY repair shop,

Yup, the downpipe from the exhaust manifold has three nuts/studs on the downstream side and you can reach them from under the hood if you have a few extensions and a swivel or two. Once those are unfastened, you can pull off the entire exhaust system from under the car on a set of ramps. It's a little tight toward the front, but it's entirely doable......before I got my lift, I did it that way more than once.

My car is a manual transmission and I didn't have to worry about anything other than unbolting the exhaust and dropping it down. I'm not sure about automatic transmission cars though. Please do keep in mind that there's a brace that holds up the gas tank, so be very mindful not to unbolt that brace or you'll be in for a hard time getting it back in place, especially if you have a full tank of fuel.

[Kolbenringe]

Yup, the downpipe from the exhaust manifold has three nuts/studs on the downstream side and you can reach them from under the hood if you have a few extensions and a swivel or two. Once those are unfastened, you can pull off the entire exhaust system from under the car on a set of ramps. It's a little tight toward the front, but it's entirely doable......before I got my lift, I did it that way more than once.

My car is a manual transmission and I didn't have to worry about anything other than unbolting the exhaust and dropping it down. I'm not sure about automatic transmission cars though. Please do keep in mind that there's a brace that holds up the gas tank, so be very mindful not to unbolt that brace or you'll be in for a hard time getting it back in place, especially if you have a full tank of fuel.

Sorry to try and clarify it again: did you remove the cat with the front section or after? There seems to be people on youtube and elsewhere mixing all the terminology and not keeping it standardized. I just want to remove the section two here: https://audi.7zap.com/en/rdw/audi+a4.../253-253060/#1

I'll do this first before the section after it because the inspection found nothing wrong with that and the shop might have been trying to add more to the bill.

[RockJGC]

Sorry to try and clarify it again: did you remove the cat with the front section or after? There seems to be people on youtube and elsewhere mixing all the terminology and not keeping it standardized. I just want to remove the section two here: https://audi.7zap.com/en/rdw/audi+a4.../253-253060/#1

I'll do this first before the section after it because the inspection found nothing wrong with that and the shop might have been trying to add more to the bill.

The cat is part of the downpipe (#1 in your drawing). If you have to remove that downpipe, it can come out from under the hood. See the flange with the three nuts (#6 in your drawing) at the bottom of the downpipe? You can get to those three nuts from under the hood and once they are off, you can remove the entire exhaust system from under the car on a set of ramps. So if you're looking to remove the exhaust system from #2 and down, just unbolt those three nuts (again, #6) from under the hood and then you can get everything off from under the car on a set of ramps. Hope that makes it clear for you.

[Smac770]

There shouldn't need to be a reason to mess with the cat/down pipe to flex pipe bolted connection.



The clamping sleeve connects the flex pipe with mini whatever you want to call it to the center muffler, which is what it sounds like is being replaced:



What seems odd in that pic is I don't see the clamping sleeves that should connect the center and rear muffler units. But it's Russia, who knows what they did to it.

https://www.ecstuning.com/b-genuine-...er/8k0253409p/

[Kolbenringe]

The cat is part of the downpipe (#1 in your drawing). If you have to remove that downpipe, it can come out from under the hood. See the flange with the three nuts (#6 in your drawing) at the bottom of the downpipe? You can get to those three nuts from under the hood and once they are off, you can remove the entire exhaust system from under the car on a set of ramps. So if you're looking to remove the exhaust system from #2 and down, just unbolt those three nuts (again, #6) from under the hood and then you can get everything off from under the car on a set of ramps. Hope that makes it clear for you.

Yep, very clear now, thanks. I'll soak them and see how easy it might be to zip them off. I'll order section 2, the gasket, and the nuts from a dealer that puts stuff online and offers discounts for car club members. I believe I have the AC suffix, since I hace a 2.0t Quattro Avant, 155kW, but I can't confirm because of the heavy corrosion where the last three digits and suffix should be. I also think I am in no immediate danger of anything blowing out. I think it just has tons of holes in the body. I really wish there was a test pipe available, but I guess it's tough due to the angles.

There shouldn't need to be a reason to mess with the cat/down pipe to flex pipe bolted connection.



The clamping sleeve connects the flex pipe with mini whatever you want to call it to the center muffler, which is what it sounds like is being replaced:



What seems odd in that pic is I don't see the clamping sleeves that should connect the center and rear muffler units. But it's Russia, who knows what they did to it.

https://www.ecstuning.com/b-genuine-...er/8k0253409p/

Yep, in the first pic is what I want to replace. I now have a hang on what's going on- front resonator. The one under the back seats is the middle resonator. And very weird you found the middle and rear section as one piece. I think my middle resonator is actually ok and the shop tried to jerk me around, but I will just order it at another time if it's also shot. The shop also seemed confused about what was the middle and the front. I think they referred to the front resonator as the middle because it's roughly the middle of the car.

[RockJGC]

There shouldn't need to be a reason to mess with the cat/down pipe to flex pipe bolted connection.

The three studs circled in red are the connection to the downpipe. So to get the mid-pipe off the car, you need to remove the nuts that connect the downpipe.

[Kolbenringe]

The three studs circled in red are the connection to the downpipe. So to get the mid-pipe off the car, you need to remove the nuts that connect the downpipe.

Yep, got it. Already started soaking them and will hit them a few times during the week. I actually replaced the clamping sleeve on the rear of that section a few months ago so it's kind of fresh and I won't need to replace that. Looks like I could probably get it out pretty quick and not have to remove the transmission crossmember like I saw in some videos. From the dealer the pipe is about 420 Euros , plus three nuts and the gasket.

So I was able to identify the part numbers on the front resonator and it appears they print a partial and then a full one. It looks exactly like the one in this link with the 8k0253211m. The partial is 8k0118c. I think, according to ETKA, I have 8k0253102ac and ECS seems to confirm this and OEM parts, an VAG parts dealer in the Czech Republic, also confirms this. Not only that, their price is radically lower than in Germany, so depending on shipping, I might go for it.

[Smac770]

The three studs circled in red are the connection to the downpipe. So to get the mid-pipe off the car, you need to remove the nuts that connect the downpipe.

It was originally stated center muffler, not front muffler, so wasn't sure why that connection was being brought up. Kol clarified he meant the front one, so on the same page now. Those bolts can suck; unfortunately, that'll be a good bit more work than some clamping sleeves.

[Kolbenringe]

It was originally stated center muffler, not front muffler, so wasn't sure why that connection was being brought up. Kol clarified he meant the front one, so on the same page now. Those bolts can suck; unfortunately, that'll be a good bit more work than some clamping sleeves.

Yeah, sorry for the confusion. The shop confused me as well. I crawled under to confirm and take pics of the part numbers and remind myself of the work with the clamp in January. Then youtubers on meth were describing the whole thing as a downpipe- from the cat to the first resonator. At this point, I know what I need, I'm just trying to confirm I have the right part numbers selected.

[Smac770]

The catalog part number for the front muffler with flex pipe for a B8 (that means B8.0 and B8.5) A4 2.0T avant is 8K0253102AC. The sedan and avant exhaust components vary due to the acoustics of the panoramic sunroof. This is one piece where the sedan uses different components. Note, the B8 Q5 uses the same front muffler as the B8 A4 avant. And the B8 A4 allroad is just a wagon like the avant and also uses the same pipe. It appears the 1.8T gets the flex pipe without front muffler.

For the sedan, we see the front muffler was originally 8K0 254 352 ... and then changed to 8K0 254 102 ... But that's not 211 or 118. It appears 211 and 118 are not in the catalog at all, which is not surprising.

As the catalog piece is a composite of several individual components, what you find stamped on any individual metal piece of the front muffler may or may not match the catalog part number. And the revision letters for components may have nothing to do with the revision letter for the composite. It would appear 8K0 253 211 is the actual muffler component itself.

https://ahparts.com/buy-used/2016-au...102ac/306072-1
Here we see a B8.5 Q5 2.0T pipe that is also 118C but 211AC. Still, we can't presume that both are not "102AC".

The problem with the catalog at times is it's a listing of proper replacement parts, not necessarily a log book of actual parts used during production. It can often be used that way, but it's clear too that history gets removed over time as well.

If we go through the 8K0 254 350 / 352 / 354 and 8K0 253 102 part revs, there appears to be three lines with front mufflers:

8K0 254 352 N > 8K0 254 352 R > 8K0 253 102 B > 8K0 253 102 R - sedan
8K0 254 352 N > 8K0 254 352 S > 8K0 253 102 F > 8K0 253 102 AC - wagon w/panoramic
8K0 254 352 L > 8K0 253 102 E > 8K0 253 102 M - wagon w/o panoramic?

I can't determine an application for 102M. All the catalog sites, old or new, list only 102AC in reference to the avant, allroad, and crossover.

I guess I need to do tire rotation, so will look at what's on my Aug '08 avant when I do that.

[Kolbenringe]

Thanks for the information and that's really interesting regarding the 1.8T vs the 2.0T. I was under the impression that the 1.8T front pipe is of a smaller diameter than the 2.0T (denoted by the smaller clamps required to connect it to the middle section).

If the front section from the 1.8T has the same pipe diameter, I would be tempted to get that over the one I have. If we're talking the 8K0254352D, I have about a 260 Euro savings over the 2.0T. Incidentally, I have the pano roof on mine. I think the front section without the front resonator would look original enough that it wouldn't trip the inspectors to cancel the road certificate.

[Kolbenringe]

Placed the order from a discount Audi dealer and they confirmed I had the right part with the AC suffix pipe.

The flange seal was not available under 8K0253115 and they checked and it was superceded by 8W0253115P.

[Smac770]

I don't doubt that the 1.8T and 2.0T use a different diameter front pipe (flex pipe with or without front muffler). It appears the 1.8T and 2.0 TDI use a 55mm clamp, and 2.0T uses a 65mm clamp. I was commenting here only on the front muffler vs not front muffler. So it appears the 2.0T front pipe differs in two aspects vs the 1.8T and 2.0 TDI front pipes.

Found the application of the 352L > 102E > 102M front pipe with muffler line. 8R Q5 3.0 TDI for Euro3 diesel (PR 0GZ) and Euro4 diesel (PR 0GG) emissions. The curious part is the the Euro4+ (PR 7MB) and Euro5 (PR 7MG) emissions versions get the no front muffler version (352F > 102D). I assume the DPF unit used for 7MB/7MG is enough of a muffler itself.

[Kolbenringe]

The DPF thing makes sense. Also of interest, but maybe not for NA audiences, is that when one punches in the part number for the exhaust front section into parts finders here, there's actually an aftermarket option to get only the section from the flange to the end of the flex coupler in stainless steel. The end of the flex coupler has a slotted outlet, fits over the rest of the pipe, and a stainless bandclamp is used or the whole thing is welded on. That costs about 130 Euros. Bosal and others make the 1.8T complete front section and that one can get for under 100 Euros in some cases.

I think I also found a torque value for the nuts at the cat outlet flange at 40NM. Seems a bit high and I don't want to snap studs. There are also instructions to use anti-seize on the threads, but those come from aftermarket exhaust makers.

[Smac770]

Workshop manual shows 25 Nm for those nuts, same as the nuts on the clamping sleeves. The nuts for the cat to the turbo is 40 Nm.

[Smac770]

Finally lifted the car to do rotation and replace a front axle ($50 for a used OE axle rather than a boot kit and messing with the old axle? Yeah, I'll do that). Was looking for that "front" muffler, it really is dead center of the car. And the "center muffler" is all the way back at the rear axle. That's a long way when you're under the car on your back. :-) So can totally see why it would not be seen as a "front" muffler in the shop.

Seems mine is even older than yours (08/08 build), marked 8K0 118 B and 8K0 253 211 F and 08 08 date.

How did getting the flex pipe flange nuts free go?

[Kolbenringe]

Finally lifted the car to do rotation and replace a front axle ($50 for a used OE axle rather than a boot kit and messing with the old axle? Yeah, I'll do that). Was looking for that "front" muffler, it really is dead center of the car. And the "center muffler" is all the way back at the rear axle. That's a long way when you're under the car on your back. :-) So can totally see why it would not be seen as a "front" muffler in the shop.

Seems mine is even older than yours (08/08 build), marked 8K0 118 B and 8K0 253 211 F and 08 08 date.

How did getting the flex pipe flange nuts free go?

I haven't done the job yet. I am planning on a trip that I ended up delaying, so will do it when I come back. It appears the exhaust is in no danger of collapsing, so I can wait. I received the front section and it was surprising to see how light it is. I also don't anticipate real problems with getting the nuts off since the studs are in the section I will replace, so I'm just going to zip them off with the impact. The engine was rebuilt a couple years ago for the oil burning, so I think things might be ok. It was likely disassembled in 2020. I also have copper grease for the studs and new nuts.

[Kolbenringe]

Now that I'm really planning this out, how the hell do I get the third nut that's not visible from the top? I guess I can use a bunch of extenders for the other two and zip them off, but I have no clue how I'm going to get the last one off and then torque it when it's back on. Any tips?

[RockJGC]

Now that I'm really planning this out, how the hell do I get the third nut that's not visible from the top? I guess I can use a bunch of extenders for the other two and zip them off, but I have no clue how I'm going to get the last one off and then torque it when it's back on. Any tips?

Extensions and either a wobble fitting or universal joints. I did mine from the top using two universal joints and a few extensions. It's not as hard as it looks.

[mc_hotmail]

Extensions and either a wobble fitting or universal joints. I did mine from the top using two universal joints and a few extensions. It's not as hard as it looks.

haha, I just did this yesterday. For the top nut, I tried then realized an universal join is not needed. I ended up using a 1/4 drive 10mm deep socket > 1/4 extension > 3/8 extension > 1/2 extension > 1/2 ratchet -- longest I have ever deviced. It worked on the first try!

[Kolbenringe]

Looks like I'm going to have to get an extra swivel and start looking through my extender collection.

[Kolbenringe]

So I finally decided to try the job to remove that section and the first fastener after the cat rounded out instantly. It's going to a shop on Monday, will be done Tuesday. They won't take my parts, which is ok, but they're charging a very low price on the parts and very reasonable labor and I could sell the parts I have for more than what I'm being charged at the shop.

Very annoying. I was soaking those nuts for like a year. I just don't have time to deal with it and will go on vacation a day after the repair.

[Kolbenringe]

Took it all to a shop, they did the job in less than an hour and just cut the old exhaust off. There was absolutely no way to do it without using a nut extractor and praying or an air hammer.