Exhaust leaking after replacing rear muffler

[ThinkPad]

---- SOLVED ---- I have let the dealer replace the muffler for an original one instead of my aftermarket one: http://www.yarisworld.com/forums/sho...1&postcount=13


Our Yaris '06 failed technical inspection because the rear muffler was quite crispy and rotten through on some points.

I replaced it (quite an easy job to be honest). However, the original muffler had the nuts welded onto the flange. The new muffler came without nuts and had just holes for the bolts to be put through.

I bought a new set of bolts together with some copper nuts and a new donut gasket. However, i couldn't get these new bolts and nuts fitted as tight as the original bolts were. Result is that the exhaust is leaking between the two flanges with sometimes a squeaky noise (i first thought the accesory belt was squealing).

The check engine light also came on, i plugged in my OBD-reader and it came up with error P0420 ("Catalyst System Efficiency Below Threshold Bank 1".). I suspect that this has to do with the leakage. I cleared the error and drive down the highway, but the light stayed away

I looked up some diagrams, but it seems that the nuts can't be ordered separately. Anyone with ideas how to solve?


Flange of the original muffler, with the nuts welded to it


Flange of the new muffler, with the new bolts and nuts

As you can see, the springs were much more compressed in the old situation. I cannot tighten the new bolts any harder because the thread isn't long enough it seems.