Looking for specifics from someone who has removed the Cats on their 2010 Q5 3.2FSI with the engine in. According to YT is doable. But I can not for the life of me figure out how. I got the first two nuts off easily. But no idea how to access the last.

Has anyone done this?
Can it be done?
Should I just scrap the car and quit?



Thank you for the help.

 

It can be done. Either reach in from above between engine and firewall with a box end swivel head clicker wrench or from below with several long wobbly extensions as in several feet long. I seem to recall the inboard bolts are not even visible so it is a do by feel deal with long extensions. Obviously do not round the inboard nut otherwise you’re in for an engine pull.

 

Miałem ten sam problem od strony pasażera, ale mi się udało.Musisz zdemontować osłonę termiczną (co też nie jest takie proste)wtedy jesteś w stanie nawet zobaczyć tą nakrętkę.Tak jak napisał AudiAllTheWay Musisz zrobić sobie przedlużki kilka połączonych razem i wtedy jesteś w stanie ją odkręcić.Przed tym wszystkim ja pryskałem mieszanką aceton i olej od automatycznej skrzyni biegów 1:1,naprawdę mi pomogło.Pozdrawiam z Polski

 

I had the same problem on the passenger side, but I managed. You have to remove the heat shield (which is also not that easy), then you can even see the nut. As AudiAllTheWay wrote, you have to make yourself a few extensions connected to each other, and then you can unscrew it. Before all this, I sprayed it with a mixture of acetone and automatic transmission oil 1:1, it really helped me. Greetings from Poland

 

Hey!Yes, removing the cats on your Q5 3.2 FSI is doable, but it takes a bit of patience and the right tools, Usually, the last nut is the trickiest, Try using a long socket wrench with an extension or a swivel joint, Raising the car can also make things easier, If you feel stuck, don’t worry – maybe it's best to leave it to a pro.No need to get frustrated.Every modification brings new experiences, so give it another shot, and you’ll definitely find a way!

 

Which heat shield are you referring to? The smog valve shield or the smaller one under the cat? The smog valve shield I can’t get out due to one bolt on the bottom end that is covered by the Cat.

Once you have the upper part of the exhaust removed do you disconnect the bottom end of the downpipe as well?

Thank you all for the help. I was ready to tow this thing to the scrap yard yesterday. Today, I will try again.

Would it be worth it to delete/gut the cat before I reinstall it all? Is there any MPG or HP gain or does it just sound better?

 

The combi-valve heat shield likely cannot be removed as one bolt is buried. It is clear the combi shield was installed then the cats were mounted on the engine and then the drivetrain was installed in the chassis during factory assembly.




Get your hands on any 12mm wrench you can find. For coming in from underneath in-line with the downpipe using a few long 3/8” drive wobbly extensions, I cut down a 12mm deep socket to just the right depth so the socket accommodates the stud length yet fully lands on the nut. Another useful trick is wrap a universal swivel with electrical tape to stiffen it and use it between socket and extensions. It was a two person job with one guiding from up top to ensure socket lands and one underneath turning the ratchet.





IMHO there is very little gain to gutting the cats unless perhaps they are melted and plugging the exhaust. You might shave 1/10th second on 1/4 mile race track with gutted cats making it somewhat mute for daily street. In my part of the world, if a police cruiser is behind you in traffic and smells the horribly stinky catless exhaust fumes then they pull you over and issue a mandatory fix-it ticket with a due date for reinspection. If you fail to follow thru with repairs then they revoke your vehicle registration. Also the catless vehicle will fail emissions testing and could make vehicle resale more difficult due to stinky exhaust along with failed Safety Inspections.

 

I don't know how to explain it, I mean the cover that is above the axle shaft. An example of a cover serial number is 8K0 407 722.

 

In this 1.59 minute sample video you can see this cover and part of the catalytic converter (this is the right side from the passenger side)

 

It is possible, I did once in order to replace the upper timing chain tensioners and the guides but I would not do it again. If you have to work on the timing then I would just remove the engine. As others said, you will have to remove the front wheels so you can gain access to the bolts that are securing the heatshield to the transmission. Once the heatshields are removed then you will have more room to access the nuts.
What worked well for me were the swivel head sockets and long extensions. From what I remember, you need both the shallow and the deep style of swivel head sockets. As you unscrew the nut, the deep one becomes too long to allow you to remove the nut.
The picture below shows the passenger side (bank 1), you can easily see the nut that is completely blocked in your picture.