I've had a qualified muffler shop repair this issue three times. I have a bonez cat and the stock exhaust manifold. It just keeps blowing gaskets. I've used three replacement mazda gaskets, sandwiched them together with muffler weld... and they stuck them on. This is the third time they do it. This time, they heated the peices up, and tightened the bolts slowly. If this time it doesnt work, what the hell can i do!?! Is it possible to weld the cat to the exhaust manifold?! Thanks
-Ross

 

I don't mean to be sarcastic, but did you try using just one gasket?

-Tesla

 

Yes... that was the first time it blew. The reason why they keep blowing (or so they say) is because the cat was taken off an fc that was rearended... so they say that it is slightly bent, as well as the flange on the cat is rippled.
Thanks

 

Then, why not get a new cat that the flange is ok on?????

 

Because rico, this is why I'm posting. To see if it's still possible to use THIS cat.

 

They should be able to cut the flange off, and weld a new flange onto it.

-Tesla

 

Or they could resurface the flange. Might just be cheaper to get a new cat though....

 

ya i'd say it's best to just trash that cat and get a bonez one if possible. or you can take out some agression and bash that cat straight and flat.

james

 

If it were me I would take the cheap way out.

Go to auto parts store and pick up some Exhaust Weld. Its in a glue type of tube and dries hard as a rock. Slop that glue stuff all over the flange and call it a day. You can even try to make that stuff into some sort of gasket if you are willing to take the thing off and spread some where a gasket should go.

 

Thanks for the suggestions guys. The muffler weld that you were talking about has been used ... not sparingly... and the exhaust has blown out again, right at the gasket. So once again, i ask.... is it possible to weld the flange directly onto the manifold? It IS a bonez cat. that's why i dont want to "trash" it
thanks
-Ross

 

Do not weld it to the manifold. Doing so would make it very inconvenient when it needs to be removed (ie. for clutch replacement). Plus, the manifold is cast iron and the flange is steel...Very difficult to weld those two metals together.

Best bet is to have the flange on the Bonez cat resurfaced or replaced, as well as the flange on the manifold resurfaces. Any automotive machine shop will be able to do it for a few dollars.

 

But these guys are a bunch of friggin idiots. To this day, i've invested over $100 to have the gaskets replaced over and over and over again. And all they say is "well its not our fault!!"... so i'm kinda fucked here... i don't want to get a new cat. i'd rather have the flange resurfaced. I don't really care if i weld that peice on. I mean if i have to remove it, i'll just remove both the cat and the manifold in one peice... no?

 

oh yeah, my clutch is new, so i'm not too worried about that

 

Quote:
Yes... that was the first time it blew. The reason why they keep blowing (or so they say) is because the cat was taken off an fc that was rearended... so they say that it is slightly bent, as well as the flange on the cat is rippled.
Thanks

I know you probably don't want to do this, but maybe the easiest thing would be to get a new cat. Then you would know for sure that all the pieces were mounting flush. Hell you could even have the muffler place just put in a straight pipe instead of the cat. You could start breathing fire!!

 

It is really no big deal to weld a new flange on...Midas or any other muffler shop can do it in 5 minutes or less. I'd try that. If you keep having the problem, have a shop resurface the flange on the manifold as well...

Just don't weld. Trust me on this. The weld will not be very good, and at some point you will have to remove it...At which point you will suddenly realise why it was a bad idea.

 

alright but i'm tired of wasting money on this. if i weld it, it will be permanent (which is what i want). I'll try another muffler shop for sure. I'm tired of these morons.
Thanks
-Ross

 

But you keep missing the fact that it is steel being welded to cast iron. These are VERY different metals, with very different welding processes. The joint will not be very good, and may simply fall apart or start to leak again in a few weeks....

BTW, have you seen the Ottawa pictures thread in the Canadian Forum? I believe your car is there somewhere.

 

Grr aaron!!! you make life difficult!!! if it wasnt for your wicked mp3 player, i'd have to kick your ***
I'll find a shop tomorrow to weld a new flange on :P
If not, **** y'all, i'm welding a 4-inch-thick bead onto the joint
thanks
-Ross

 

Aaron, your site is down buddy, i tried getting those pics, but get yer server working first i hope you took some pics of my system

 

LOL....Hmm...The site is working now...Probably something temporary...I only got two pictures of your car...One from the side, one of the engine bay....I wish I had taken more pictures of EVERYTHING!

 

I was having almost exactly the same issue on my T2! I have a downpipe, then there is a crappy mazda pipe between it and the Bonez cat, and then my N1 catback. It kept popping leaks right between the downpipe and the crappy mazda pipe. Romeo at T&R noticed that the flange on the crappy mazda pipe was bent, so to fix it, he threw away the crappy mazda pipe, hacked the flange off my cat, and then welded a beautifully sculpted piece of pipe onto the end of my cat, running to the downpipe with the flange re-attached on the end.

The car is much quieter now, and runs better. Idle is improved, especially. It finds the 750rpm mode much sooner now, it used to take a long time and a bit of hard driving to make it idle there instead of 1000-1500.

Also, it sounds badass! No more screeching wooshing sound coming from under the car at WOT...