How to Install Downpipe Audi A4 B8.5

Virginia Pirits · Thursday 3 March 2022

This is really a pretty easy job if you take the correct tools. I had read that it is a real PITA but I thought it was actually pretty simple. I ran into ane problem requiring some cutting and drilling but had that non happened, I recall I could do this in about iii hours. From what I could tell, the process is nigh identical to what you do with the B6/B7 cars. You volition need a helper for about 10 min which will make it l times easier than if yous are trying to exercise it solo. They don't have to get under the motorcar or anything. Information technology will assistance if they don't have massive hands and forearms.

Step i: Remove the auxiliary cooling fan shroud. Remove the airbox. Remove the turbo inlet hose. This is what you're left with.

Step 2: Disconnect both O2 sensors. The main sensor wiring goes through a small clip on the exhaust manifold estrus shield then the connector mates on a plastic subclass on the ignition coil harness assembly. The bracket and mating connector are shown below.

You tin and so remove the principal sensor using an O2 sensor tool.

The secondary O2 sensor is routed between the aft of the engine and the firewall. The connector mate is done on a bracket installed to the commuter'due south side of the transmission. The picture below shows after I de-mated the connexion. I had to spray a piffling WD-xl on the bracket in order to slide the connectors out of the bracket since it was a tight fit. It's easier to safely de-mate the connectors after you take them off the bracket. There are ii zippo ties you volition have to cutting that tie the sensor wire down onto other wiring harnesses. Later you disconnect it all you can route the sensor wire dorsum to the cat in preparation for removing it.

Step iii: Remove the 3 basics you tin get to that connect the cat to the turbo using a 15 mm wrench. Spray them all downwardly with PB Blaster. The two on the rider side are easy to accomplish. I was able to get the upper driver's side bolt using a normal 15mm craftsman combination wrench by alternating using the box cease and open terminate in different orientations. None of the nuts were very tight but possibly that is considering my car only has 36k miles on it. In some other 5 years mayhap they will be a lot tougher. You can see the 3 that I was able to remove in the picture beneath.

Step 4: Remove the shock absorbing link assembly that connects the lower portion of the cat pipe to the engine. The lower commodities between the link and the engine will require a 12 mm combination wrench. The upper bolt (where the spring is) will require a thirteen mm combination wrench from below to loosen the bolt and a thirteen mm combination wrench from the summit to hold the nut. Yous volition need a helper from higher up to agree the nut considering the way it is oriented you can't accomplish both sides and turning the bolt will only cause the nut to spin. When you reinstall this later on yous won't need a helper because the pipe is smaller and the bracket it mounts to is different so yous will be able to reach both sides. Perhaps you lot can go the cat out with this link installed only the stock cat is a tight fit so I went ahead and removed it. Y'all'll demand to remove it anyway once off the car because it volition get installed to the new true cat.

Stride 5: Disconnect the downpipe from the midpipe. You can meet my connection below. Midpipe is to the right, downpipe is to the left. I had just installed a new frazzle (aft of downpipe) two weeks earlier. I didn't employ exhaust paste at this joint considering I knew I'd exist taking it apart in a calendar week or ii to practice this project. That is why y'all tin see the black marks indicating some exhaust had been escaping at this joint. Both clamp bolts on mine were xv mm. I tin't recall if the bolts from the stock frazzle were 15mm or not. You'll demand a deep well socket to get over the bolts and onto the nuts. Once the connection is loosened y'all'll need to slide the downpipe forward (it isn't going to movement much) and the midpipe backward to become the slip fit connection autonomously. I couldn't go enough space and then I had to remove the muffler hanger bracket so that the exhaust could exist slid dorsum farther. You'll probably accept to do the same thing. Spray the connection down with some WD-xl to get the two sliding a trivial easier confronting each other.

Footstep 6: At present you've got to get out the final nut holding the true cat to the turbo. I rigged upwards the combination of sockets you see below and had a helper in a higher place assist with getting the socket onto the commodities. The sequence was: 15mm deep well socket – swivel - 10" extension – swivel - 18" extension - 6" extension - ratchet. It would be damn near impossible to do this yourself. I suppose if you were stranded on a desert island and had a couple weeks to do this then you lot could probably practise it yourself with but a 50:50 take a chance of hopelessly stripping the commodities. It took usa a half dozen tries to become it on the nut securely only one time it was on, the nut came right off.

Step 7: Now you can pull the downpipe rearward so that the connection between it and the true cat tin be reached. Hopefully y'all've been spraying copious amounts of PB Blaster on these three nuts ever since you started the install because the nuts are inexpensive and they volition be completely seized in place. I only got one of the three to come off. I retrieve they are 12 mm. The other two got completely stripped. I bankrupt out the dremel and cutting the two bolts off. The problem I and so realized is that the bolts are pressed into the downpipe flange and tack welded in identify. So I couldn't merely hammer them out. I had to cut them flush with the flange and then drill them out. And so go replacement hardware. It wasn't likewise bad because yous have easy access to the spot but it was still a pain. Hopefully you take improve luck than me and hopefully your cat comes with new nuts so you don't have to put these three crappy ones back on, thereby almost eliminating whatever promise of ever de-mating this connection in the future.

Step 8: At present you should be able to wedge the true cat out the top of the engine. It is a very tight fit with that secondary O2 sensor still installed, but it is and then buried that you have no hope of getting it out with the cat in the engine bay. But pull hard and get things oriented correctly and information technology will come out. Remove the secondary O2 sensor once you have information technology out of the engine bay.

Transfer the secondary O2 sensor and the shock absorbing link over to the new true cat. Installation is the reverse of removal, except that you'll take more than infinite to piece of work with considering your new high flow true cat or test pipe is way smaller in bore than the stock cat. I recall if you are installing a test pipage that you lot can actually get all four of the TP to turbo basics on from the pinnacle of the car. You should have gotten two new gaskets for either end of the true cat and those will get in during the reinstall. Here is what your finished production is going to await similar. Now go get a tune and start taking solace in the fact that your car is no longer slower than a V6 Toyota Camry.

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