Exhaust Advise

[Chef]

My 1992 legacy exhaust is finally coming to the point where the only feasible repairs are replacement of mos tor all of the system behind the first cat. The pipe connecting the first and second cats was "repaired" by a shop not long ago, but it was a shoddy job that leaked shortly after (the guy used silicon to fill in gaps between old and new pipe).

 

I went to a shop today and was quoted about $750 (cdn) plus tax for the everything behind the first cat. I am struggling to put gas into my car these days, and may or may not keep it for more than another year or two depending.

 

So I've decided to repair the worst leaks with some cement temporarily, and get to work figuring out the least expensive means to repair this. The second cat is ok, but the pipes connected to it are getting lousy. I have access to a welder at work, but never used one before. I am willing to try and do this myself, preferably using as many flanges and as little welding as possible. I am inexperienced but handy.

 

Any advice would be welcome. I am uncertain how these systems usually are pieced together (e.g. if using male/female insertions, are they held together by some compound or just clamps?).

 

I need to keep the cats. My thoughts were to clean the ends of the cats, and weld pipes or flanges to the most convenient ends and buy the closest fitting pipes. Then use flex pipe in one or two spots to help align it all. I'll measure the dimensions of all pipes, map them out in relation to a diagram of the bottom of the car, then have a shop cut and bend any necessary pipes.

 

I am a little uncertain about how to place hangers though. Should I weld them to the pipes in the places they currently are, or is there a better (easier) method.

 

Thanks all!

 

Chef

[idosubaru]

i knew (know??) nothing about welding and did it myself a couple days after buying a welder too. it is possible. but it is also a pain.

 

i think the cheapest alternative would be to buy a good used exhaust (post a in the Wanted to Buy Forum here on this site). You can probably get one for $100 or less. i've sold exhaust parts before, that's the cheapest and easiest route in my oppinion. treat/paint the rust with high heat rust proof quality paint to at least mitigate any existing rust.

 

you should also be able to get this job done for $200 or less at an honest local muffler shop for a generic off the shelf muffler and new pipe from the cat back. $50 in parts and $150 in labor should be easily possible (if not cheaper). i threw a muffler i bought in my trunk and kept it in there for awhile and stopped at a few shops and finally found a place that said they'd do it for $35. they ran new pipe almost from the cat all the way back to the muffler and hung it for only $35. shop around and look for a place that'll weld/replace the pipe and muffler with non-OEM parts. if they're buying direct fit bolt on replacements you're going to pay high dollar. not cost effective in my oppinion.

 

if you still want to do this yourself....i bought a ton of flanges and gaskets and pipe. i took the old muffler and pipe (the one i had welded for $35 years earlier) to a shop and had them bend me new pipe where the two bends were in the exhaust. i welded one directly to the muffler and the other had flanges. i would not mess with that flex-pipe it is terrible quality. not bad for a mock-up maybe but i'd just take in the old stuff. they can bend close to that. mine is bolted to the motor and i have one hanger at the muffler, that's it. use the stock locations, i only have one hanger on my muffler and that's it. i don't use the mid-hanger because i didn't feel like welding it on, didn't seem necessary. worked fine for me. the front is held in place by the engine/exhaust manifold. get verything held up and lined up as best as you can. tack it in place and remove and fully weld all the parts. i did one piece at a time and worked my way front to back. bolted the first flange to the existing exhaust manifold flange. set the pipe about where i wanted it, then tacked it to the flange. removed the flange with pipe now spot welded to it and fully welded the flange. reattach and repeat until you're finished.

 

tips: buy extra pipe and extra flanges and take back what you don't need. make sure the pipe, muffler and flanges (mostly the muffler will be the issue since pipe/flanges are usually not stainless), make sure they are not stainless unless you want to be welding stainless yourself. stainless steel can't be welded by all types of welding machines. practice welding the pipe on some junky pipe or practice pieces and a flange, pipe is thin and you need to practice a little for yourself and to get the welder settings adjusted right for the thin pipe. pipe will melt through easily.

 

look for flanges that have good clearance between the bolt holes and the exhaust flow where the pipe will be. reason is that if it's your first time welding you don't want to be confined to making a perfect, tiny weld next to the bolt holes. what will happen is you'll make a large weld. around the pipe, then when you insert the bolt, the head of the bolt will catch on the large welds around the pipe. more clearance there will give you more flexibility, be more forgiving and less time consuming.

 

good luck and have fun!

[Chef]

Excellent, just what I was looking for! Thanks much for the detailed information. I may end up having a shop take care of this then, after I find a muffler on sale. The place I was quoted at probably does a good job, but they wanted to use all pre-fab parts etc.

 

Thanks again,

 

Chef

 

 

i knew (know??) nothing about welding and did it myself a couple days after buying a welder too. it is possible. but it is also a pain.

 

i think the cheapest alternative would be to buy a good used exhaust (post a in the Wanted to Buy Forum here on this site). You can probably get one for $100 or less. i've sold exhaust parts before, that's the cheapest and easiest route in my oppinion. treat/paint the rust with high heat rust proof quality paint to at least mitigate any existing rust.

 

you should also be able to get this job done for $200 or less at an honest local muffler shop for a generic off the shelf muffler and new pipe from the cat back. $50 in parts and $150 in labor should be easily possible (if not cheaper). i threw a muffler i bought in my trunk and kept it in there for awhile and stopped at a few shops and finally found a place that said they'd do it for $35. they ran new pipe almost from the cat all the way back to the muffler and hung it for only $35. shop around and look for a place that'll weld/replace the pipe and muffler with non-OEM parts. if they're buying direct fit bolt on replacements you're going to pay high dollar. not cost effective in my oppinion.

 

if you still want to do this yourself....i bought a ton of flanges and gaskets and pipe. i took the old muffler and pipe (the one i had welded for $35 years earlier) to a shop and had them bend me new pipe where the two bends were in the exhaust. i welded one directly to the muffler and the other had flanges. i would not mess with that flex-pipe it is terrible quality. not bad for a mock-up maybe but i'd just take in the old stuff. they can bend close to that. mine is bolted to the motor and i have one hanger at the muffler, that's it. use the stock locations, i only have one hanger on my muffler and that's it. i don't use the mid-hanger because i didn't feel like welding it on, didn't seem necessary. worked fine for me. the front is held in place by the engine/exhaust manifold. get verything held up and lined up as best as you can. tack it in place and remove and fully weld all the parts. i did one piece at a time and worked my way front to back. bolted the first flange to the existing exhaust manifold flange. set the pipe about where i wanted it, then tacked it to the flange. removed the flange with pipe now spot welded to it and fully welded the flange. reattach and repeat until you're finished.

 

tips: buy extra pipe and extra flanges and take back what you don't need. make sure the pipe, muffler and flanges (mostly the muffler will be the issue since pipe/flanges are usually not stainless), make sure they are not stainless unless you want to be welding stainless yourself. stainless steel can't be welded by all types of welding machines. practice welding the pipe on some junky pipe or practice pieces and a flange, pipe is thin and you need to practice a little for yourself and to get the welder settings adjusted right for the thin pipe. pipe will melt through easily.

 

look for flanges that have good clearance between the bolt holes and the exhaust flow where the pipe will be. reason is that if it's your first time welding you don't want to be confined to making a perfect, tiny weld next to the bolt holes. what will happen is you'll make a large weld. around the pipe, then when you insert the bolt, the head of the bolt will catch on the large welds around the pipe. more clearance there will give you more flexibility, be more forgiving and less time consuming.

 

good luck and have fun!