Exhaust allergy

  • Sun 16 November 2014
  • misc

I have long joked that while I do a lot of my own car maintenance and repair work, I have an allergy to exhaust systems. This is borne mostly out of painful experiences as a teenager - exhaust is just not the sort of thing one can successfully tackle without at least a couple of specialized tools.

A couple of weeks ago the exhaust on the Toyota gave up. More precisely, the rear of the muffler that I had put on 55k miles and six and a half years ago rusted out, leaving the truck much louder. I decided with some trepidation to do the job myself, preferring to save maintenance budget for eventualities such as fixing the air conditioning.

I've developed a preference for AutoZone over Advance Auto, partially driven by local staffing choices, partially driven by a good online ordering system. Rummaging around, I discovered that a stainless steel cat-back system was available at a mere $30 premium over the cost of the default system. Cool. Anything to avoid having to do it twice (even though I don't plan to keep the Toyota for another 55k miles and six years).

I mentioned specialized tools. My pal Tan said that if it were him he wouldn't even bother trying to get the bolts loose and would just attack it with an angle grinder. Good idea. But why stop there? I reasoned that getting the old bits out in pieces would be easier than all at once, particularly getting it un-hung from the aged rubber hangers. So in addition to the angle grinder I got the Sawzall out.

A word is probably due about the blade I used. Milwaukee didn't make my Sawzall; I have a 25 year old Makita knock-off. But they all take the same blades, so you can use a Milwaukee blade in mine, no problem. Milwaukee has a line of blades called The Torck - metal-cutting demolition blades. I've used them to cut pipe and to shorten a 19" relay rack, so why not tailpipe? Joe-Bob says check it out.

With some effort I ground off the bolts and cut out a section of the tailpipe. Still couldn't get the flange fitting to the catalytic converter apart. Odd. Then I looked closely and realized it was welded. Not gonna come apart. I have vague memories of Tom at Fix Your Toy telling me that there was an issue with the rear flange on the catalytic converter and that he'd welded it rather than replacing the cat... and that it would hold on for some indeterminate period of time before needing replacement.

So here I was with the flange and the remainder of the tailpipe welded to the catalytic converter. I don't have a spare catalytic converter on the shelf, and the cat itself is fine - it's just the output flange that's welded to the remainder of the exhaust system. Time for Plan B. There's intentionally a lot of dimensional slop in exhaust systems so I figured we could deal with the cat-back part being shifted 3/32" to the rear. Got the Sawzall back out and cut off the remainder of the old system's pipe as close up to the flange as I could and then spent 10 minutes with the angle grinder getting it down and as close to flush to the flange as possible. In the end I got a nice smooth flange, the "back" of the flange from the old exhaust system. I was now able to bolt to the "wrong" end of, still nicely welded in place to the catalytic converter.

New tailpipe in. Bolts in. They were almost too short, so I skipped on washers. I put anti-seize on them. Tan reminded me that stainless needs anti-seize on it when assembled if you want a prayer of disassembling it again. Stainless is much more prone to galling than low or medium carbon steel, almost as bad as aluminum.

Anyway, I've got the Toyota back. It wasn't that bad. At this point I might just be motivated to track down the exhaust leak in the Ford. Maybe after I fix the passenger side power window.