Foz

So I bought the exhaust system with catalytic converter for $50 (pic below). I have a neighborhood friend mechanic who does small jobs for good prices who was going to bolt the new exhaust on for a few bucks.

BUT, the car being 26 years old, the bolt head just snapped off when he went to remove the Euro exhaust system. So the estimate jumped to $130-$160 to drill out the bolts and hook everything up.

Three questions:

1) Why doesn't anyone use stainless steel bolts when assembling exhaust systems? I don't mean an entire stainless steel exhaust system, but even just the bolts would seem to prevent some of this rusting/freezing/breaking that is so common with exhaust systems.

2) What are current best practices for putting an exhaust system back together? Is there some kind of good name-brand anti-sieze that everyone uses?

3) Are the nuts connecting the exhaust manifold to the Y pipe welded to the flange (see attached Factory Service Manual pics)? If I decide to do this myself, what exactly am I going to need to do? Just break the bolt heads and nuts off, hammer the bolt shaft out, and put new hardware on? Or am I going to have to drill & retap? I haven't done much with exhaust systems before. How big a job is this for a non-master mechanic?

PorKen

The exhaust manifold to Y-pipe fasteners are through bolts and nuts, not studs. Just put new M8x35 bolts and nuts on there. (Heck, you could use 5/16" bolts if you don't tell anyone! )

Garth S

The crusty bolts are generally mild steel, and can easily be twisted until they fail. If that doesn't work, a Dremel cut-off wheel, zip disc on a grinder, or hacksaw blade are all capable.
If you plan ahead, a trip to a garage to have an acetylene cutting tourch make a quick pass will save a lot of work ...
I too agree with putting everything back together with stainless hardware - it has subsquently always come apart easily .

weirdscience

I use copper grade antiseize on all exhaust hardware. Generally Ive found any antiseize wont last on manifold or header hardware because of high heat, you just have to recoat them from time to time when your under the car doing maintenence. On the rest of the hardware it usually lasts. I do exhaust swaps and installs in my shop all the time and charge by the hour. A system like yours should only take a shop 1-1.5 hrs. There can be problems with frozen hardware but a good shop knows how to remove them quickly with an acetelyne torch and/or the proper removal tools. If you do it yourself be well prepared with new hardware ( to replace broken ones if it happens ), gaskets, PB Blaster penetrating oil (works the best) and plenty of hand tools (metric).

weirdscience

If you use stainless steel hardware, use plenty of copper grade antiseize. Stainless on stainless will gaul up and seize the first time you try to take them apart....Good luck

Foz

weirdscience: Is there any reason not to use nickel-grade anti-seize? It seems like both copper & nickel-grade anti-seize would work with stainless steel, but nickel-grade has a higher working temp (2600F vs. 1800F).

Did some more research and found out this important point -- If you use stainless steel, do not use anti-seize containing graphite:

"The use of graphite is also limited by its tendency to facilitate pitting corrosion in some stainless steels, and to promote galvanic corrosion between dissimiilar metals." --Wikipedia

"NICKEL-RICH™ is our highest temperature rated anti-seize and lubricant. It contains no copper or graphite (graphite carbonizes above 550 degree F and weakens stainless steel.)" --RectorSeal

"Nickel is the preferred anti-seize for use on stainless steel since nickel prevents stainless galling better than any other anti-seize. Nickel also has the highest temperature rating of any anti-seize." www.sacskyranch.com/antiseize.htm

RyanPerrella

Foz

good anti-seize points there, i had no idea there were any real differences in the stuff

JEC_31

Damn, I love this forum. It's so educational!

I only wish I had read this before I DIY'd my daily beater's complete exhaust system with stainless bolts and no anti-seize - oops. Hopefully the poor little Honda will rust into pieces before I have to work the exhaust again.

Imo000

When working on my exhaust I found SS bolt to be too soft. They would easily stretch and the next time they have to come off they would just snap like regular mild steel bolts. Because of this I didn’t find the need to use SS and just simply replaces the old exhaust bolts with new mild steel ones.

weirdscience

Nickel grade will work also, Ive always used copper grade with good results. You can also use copper nuts as on the 911 heat exchanger studs...

Foz

Garth: Thanks for the great tip about using the Dremel -- Slow & uses up cut-off wheels like they were going out of style, but a lifesaver.

So I broke, ground, or Dremeled off the nuts, and broke off one of the bolt heads, but I am not able to pound out the bolt shaft with a hammer. Either the flange is threaded (seems to be unlikely) or the threads have frozen/merged into the passageway.

What are my options at this point? Do I have to drill out the bolt shaft, or can I saw off the Y pipes, stick a screwdriver between the exhaust manifold flange and the Y pipe flange and pry them apart? Please see attached pic.

Any and all suggestions appreciated.

JEC_31

Looks pretty dry in that pic.

Get some good penetrant-lube, either PB Blaster or Aerokroil (sp?). WD-40 is OK in a pinch, but is perhaps half the strength. Soak liberally, wait, soak again, then hammer away.

Good luck!

Foz

Indeed, I haven't used any penetrating oil yet. My bad. But the original shop did put a tiny bit on the nuts and also tagged it for a sec with an acetylene flame before they broke off the first nut and raised their estimate.

What exactly does this mean? Do you mean cutting the hardware off with an oxy-acetylene cutting flame, or just tagging the hardware with a mild flame to thermal cycle the hardware? If it is the latter, then can I just use a propane or MAPP gas torch to do the same thing? (Avoiding the fuel lines of course)

Shane

Exactly why I don't use SS hardware. Once the nut gauls onto the bolt (fused together) You are stuck with the dremel, unless you have a plasma torch. Oxy-acet won't do anything to the SS bolts but continue to fuse it together.