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Discussion Starter · #1 ·
Discovered a faint rattle coming from one of my converters last week and sure enough this week I get the CEL for efficiency below threshold. I have a 99 V6 Tip with 122K.

I've done searches to find the best replacement option and there seems to be very limited info on these boards (which surprises me because I know there are many Passats with more than 122K). So far, in spite of the steep price, dealer converters seem to be what to go with (I'll be installing myself). It seems the only direct fit replacements are OEM or a brand called DEC. While the DEC units are less than half the price, I have no insight as to what kind of quality they are and I know firsthand how bad aftermarket converters can be. The last thing I want to do is go through all the work of changing them and find they don't satisfy the OBD2 system.

I did hear that OEM converters for the Canadian market are available for less and would work but I don't know how to get them without going to Canada.

Anyone have more information or other alternatives? Also, is there anyone here that has tackled the replacement on a V6 Tip that has insight in to what is involved? It doesn't look easy and it appears at least the subframe has to be dropped.

Thanks in advance.
 

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Are you certain that you need new converters?
Have you been under there to take a look?
If the rattle you are describing is an exhaust leak then you might not have to replace you converters.
I think the most likely problem is either that you need a new O2 sensor or that you need the emmissions reflash or the exhaust leak could be causing the emmisions cell but i don't think that means you have to replace the cats.
http://www.passatworld.com/forums/showthread.php?t=190147&highlight=sharky+atq+p0431

The flex bellows fail frequently on these cars and could be the source of the exhaust leak.
On my 2000 v6 140k in the same year I had to do both the reflash and replace both flex bellows.
The exhaust leak could be causing the emmisions cell but i don't think that means you have to replace the cats.
let us know what you find out.
 

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Discussion Starter · #3 ·
Glucks, I wish you were right. When I started to hear a faint rattle I put my ear near the converter and that was it alright. After that the rattle got worse very quickly and the CEL for lack of converter efficiency came on. I have since bit the bullet and picked up new OEM converters. I'll be starting the job soon so I'll post my experiences. Thanks.
 

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I had an S4 in the other day for a timing belt and he had the same problem. He was only at 110K (on the original timing belt too).
 

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The flex bellows fail frequently on these cars and could be the source of the exhaust leak.
On my 2000 v6 140k in the same year I had to do both the reflash and replace both flex bellows.
The exhaust leak could be causing the emmisions cell but i don't think that means you have to replace the cats.
let us know what you find out.
I just had one of my flex bellows fail today. What was your fix? I'm thinking I should be able to have a shop weld new ones in.
Curious to hear how yours was fixed.
 

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ive got that stupid emmisions workshop code comes up everytime i drive with 127k v6, but it doesnt really affect gas mileage or anything i still get like 25 highway
 

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I just had one of my flex bellows fail today. What was your fix? I'm thinking I should be able to have a shop weld new ones in.
Curious to hear how yours was fixed.
I took the down pipe with cats out myself, chopped the old flex bellows out, and had my brother weld in some new ones. The job was a pain in the ass. but I wasn't interested in paying someone $700 dollars to do both flex bellows. The quote I got was $350 a side and I couldn't find a shop willing to do it with the down pipe still in the car. others have managed to find somebody to wled on the car which will save you a ton of money. if you know a good muffler shop you might be in luck
 

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vwfleet is a rattling converter a known sign of it's failure? I have never heard of that. I had assumed their failure is generally due to being plugged up which is evident through smell, performance and CEL.
 

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Discussion Starter · #10 ·
Glucks said:
vwfleet is a rattling converter a known sign of it's failure? I have never heard of that. I had assumed their failure is generally due to being plugged up which is evident through smell, performance and CEL.
Yes, I think it is a pretty common converter failure. My neighbor had it happen on his 98 Accord and after telling various other people about my situation, they pipe up with something like "oh, I had that happen on my 198x or 199x whatever vehicle". I'm not entirely sure what happens, by my guess would be that the ceramic material that borders the outside skin eventually degrades from all the heat-cool cycling. It then gets loose inside the can.

I started the job last night and got the left side converter almost replaced. It wasn't nearly as bad as I feared. I wasn't sure if I could snake the pipe with it's big flange on the end out past the auto transmission mounting area, but it did just barely make it.
 

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Discussion Starter · #11 ·
Job Finished!

Ok, I finished the job. Things I learned: 1)The subframe does not need to come down to replace the converters even on V6 w/tiptronic. 2)Remove the heat shields above the inner CV joints, the drive axles, and the heat shields above the transmission mounts. 3)The left cat is easier to replace than the right. Access from above that is needed for removal of the oxygen sensor and/or the top nut on the downpipe flange is obtained on the left by just moving the coolant tank out of the way. On the right side you need to remove the plastic intake tube from the throttle body. It's also more difficult to get at the top exhaust nut and the oxygen sensor on the right side pipe. 4)Having a crowfoot type oxygen sensor socket was a life saver.
 
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