kjbu

Hi

Want to share my experience with how to repair flex exhaust pipe between primary and mail catalysts. This flex part seems very weak and is something that will fail on your car. Mine has gone 140k km and has now failed at least 2 times.

The part is number 10 on picture in bottom.

Some sites on net mention need to lower engine to fix it. Some manage to weld a new part inside the car, very little room to work there.

This is how you can do it :

1. Put car in neutral gear and disconnect battery (IMPORTANT - you will work with tools centimeters from + terminal on starter)

2. Remove all 4 O2 sensors (was easier than expected, no/little rust)

3. Use 12mm socket to loose the exhaust part with primary catalysts from exhaust manifoil. The nuts are directed downwards and is hidden, 3 on each pipe, 6 total. Use a mirror if you can't find them. Feel them with your fingers. They was also easy to remove. You need a 12mm socket with extension on some of them, and is also good to have a 12mm wrench with ratcheting end.

4. About on the middle of the exhaust part, there are two bolts you need to remove as well, connected to engine, beside starter.

5. Lift car and place on stands.

6. Remove front driveshaft that is preventing good access to exchaust pipe below car. A torx socket is working fine, the bolts are easy to remove. Car needs to be in neutral so you can turn the driveshaft to get access to all bolts.

7. Separate the connection between flex exhaust part and main catalyst. This was the hardest part. Bolts are not bolts any more, only some rusted things. Do your magic here, took me 3 hours. It may be easiest to cut the flex pipe, but REMEMBER to mark how it's assembled so you know what angle the connection need when welded back.

8. Loosen other side of mail catalyst, and remove mail catalyst part. There are 4 bolts needed to be removed as well. You will see it easily

9. Now, get help from a friend/wife to get the part with primary catalysts out in bottom, where you removed driveshaft.

10. Take the whole part to an exhaust repair shop, instruct them to order a STAINLESS flex pipe to replace the broken flex. They need to cut the old one away and weld in a new one. You don't want to buy the whole part ($2000). New flex and welding will cost $100-$250 depending on your country. Remember to get the connection welded on with the same angle, else you will get problem when connecting main catalyst pipe.

11. On main catalyst pipe you need to remove the rusted bolts. Hammer, heat, use your magic

12. Order new seals.

13. When mounting back in car, use 8mm stainless bolts/nuts so it will be easier to remove it next time.


It took me 8 hours to get the part out of car the first time. Next time I will manage it in 2 hours.
It should be possible to fix it when it's in the car, but there are very little space to weld and you don't see much. Previous owner had a new flex welded in place, but the weld was very bad because of difficult access. Probably that's why it failed so fast. It was probably only galvanized as well.

Will add pictures later if I take some.

Shawn Stanford

Good post.

My flex pipes went at around 100k. I had my indy replace them with the Touareg pipes, which were identical. Saved me $800 on the pipes. The entire repair came to less than the cost of the Porsche part.

kjbu

Update : Assembled together an evening, took a few hours in home garage.
Everything working perfect, engine is very quiet now. Total cost for part/welding was 2000NOK ($240).

Here is picture of the exhaust with new stainless flex pipe welded in place.
Lets hope this will last longer than galvanized.

JAGMAN1

Nice job. I've done this same thing before on another vehicle. My recommendation is to order a stainless flex coupling and then take the whole thing to a welding shop. They will weld it using stainless welding wire, whereas all but the best exhaust shops will use mild steel welding wire. A welding shop will do top notch welds too. Or learn to weld in stainless yourself. This is what I did and now I have a welder.

Lastly these things usually start to fail because of sagging engine mounts. The mount sags or settles, which puts stress on the flex coupling and you get tear away.

mdistel

My 2009 V6 has developed a gurgling/puttering sound at idle from the flex pipe area but its not really loud yet. I tried listening with a stethoscope and feeling for the leak but couldn't pinpoint it. The flex pipes both show wear as the outer braiding is loose so I'm pretty sure it's them but does this sound like a reasonable diagnosis?

I started working on the 6 lower rusty bolts and got one off with vice grips as the backside rusted so bad. I'm going to cut the remaining backsides with a Dremel and flexshaft then replace with stainless hardware.

Once out I'll take to a local Porsche shop that is familiar with this repair.

Mark

mdistel

I removed the (6) 16mm nuts at the manifolds without too much trouble after removing the heat shield. One stud came out but that's not a big deal. Accessing the bracket that joins the two cats looks difficult and the bolt is rusty. 3 of the O2 sensors were easy to reach and remove, 4th I'll get from below or later.

95_993

Is there a similar DIY for CS? I hear a small leak in the flex pipe area but it looks tricky to get to all the fasteners.

mdistel

I have the cats out and the flex pipes are both in bad shape as I expected. 1 was hanging on by only a few mm so it came loose in the removal. Agree with Kjbu that removing the lower bolts is most difficult and on my 3.6 there is very little room and 3 more to remove. I used a combination of vice grips, dremel cut-off/grinding, and wrenches. I'm a bit concerned about how the alignment will be afterwards as the non-broken flex pipe can rotate so I'm not sure what the correct position is.

Shawn Stanford

Are the part reference diagrams clear enough?

mdistel

Removing the pipes is probably not the best route to go for the dual 3.6 pipes. No local shop would weld in new flex pipes out of the car. The local Porsche shop does do an in car fix without welding so I went that route. I purchased 2" x 8.5" flex pipes and had a local chain stretch the ends so they would slip over the pipes. Crush u-clamps and exhaust cement creates a solid seal. Fitting this in is very difficult due to the lack of space. This is a 10 on a 10 scale job but doing it for <$100 vs. $850 plus the satisfaction makes me not totally regret it!!