B pipe replacement and rusted nuts

Hello. I have a 1995 Accord Ex (F22B1) that needs the B pipe and
muffler replaced. I have the required parts and gaskets, but am having
a problem removing the nuts that connect the existing cat and B pipe.
The nuts are substantially rusted, and I don't have a metric or
standard socket that will fit securely over it. The nut appears to be
13mm, but the rust is preventing the socket from fitting over it.

So, what is the "standard" procedure for removing these nuts? Muffler
shops must deal with this every day. Most of the rusted bolt/nut
threads I've read seem to either say "cut it out" or make the
assumption that you can get a good socket over the nut or bolt head.

If I can't figure this out I think my only option would be to replace
the cat and B pipe as a single unit since I can't seperate them.
Hopefully someone with experience can help me out. Thanks in advance.

 

Try the penetrating oil "PB Blaster" first. Around $4 for a
large can at places like Autozone and Wal-Mart. Soak for at
least an hour. Repeat application. This, with a large
breaker bar and/or a hammer applied to the wrench end, has
worked on every exhaust system nut/bolt I've had to remove
on my 91 Civic, from those at the manifold to those on the B
pipe.

You can't get any socket over the nuts? Try a little
persuasion with a hammer.

A compressed air driven angle die grinder ($6 to $20 at
places like Autozone, Harbor Freight, Pep Boys) may also be
used to cut such nuts off. Get a "cutoff wheel," not a
grinding wheel, for it. Of course this assumes you have a
half decent home air compressor, say 100 psi at 4 CFM. Try
to cut in a direction that loosens the bolt or nut. I have
had a lot of success with this on the tricky control arm
bolts and nuts.

A lot of people recommend applying heat with a torch. Check
the archives for more on this.

 

catalytics are expensive.

use a nut splitter or a cold chisel to remove the rusty nut,then clean up
the stud's threads and use a new nut.If you can get a Dremel hand grinder
with a cut-off disc in there,that can start a nice cut for the chisel to
finish.
(back when Craftsman was tops,they used to make a nice set of thread-
chasers to clean up rusty/dinged bolt threads.I have a set for US threads.)

I suspect shops have air-powered chisels,making it a lot easier.

 

Thanks for the responses so far. If I can't hammer the socket over the
nut and were to instead cut off the rusted nut and bolt with a dremel
tool, would I be able to replace the bolt coming from the cat or is it
spot-welded to the cat? The service manual isn't clear, and I haven't
yet taken the heat shield off the cat to inspect the cat-side of this
joint. Because maybe the bolt should be replaced anyway, since it also
apears a bit rusty?

 

See if the exploded parts drawings at www.slhondaparts.com
offer any insight.

 

It's probably a stud welded to the cat. The best way to do this, given my
experience doing exhaust work, is to heat the nut up. Most mechanics would
use a small tip on their oxy-acetylene torch. However, you might be able to
get by with a MAPP gas torch (just make sure that it's one that puts out a
nice conical flame, I've seen some which produce a very diffuse flame which
isn't what you want most of the time). Heat up the outside of the nut until
it's red and then turn it with a socket. Use an impact type socket or you
can risk taking the temper out of a chrome socket and then it could easily
break the next time you use it.

With regards to the nut size, Honda usually doesn't use 13 mm sized
fasteners. It was probably a 14 mm at one point. I suggest using a special
"twist" socket that works great for stripped or rusted nuts/bolts. You can
find some examples at http://tinyurl.com/hrp8a and
http://tinyurl.com/kg9td. They are worth their weight in gold when it comes
to removing rusted or stripped nuts.

Eric

 

I was able to complete ths job today, so thanks to all who gave their
advice. As I mentioned before, the problem I was having was removing
the rusted nuts off the bolts that connect the catalytic converter and
the b pipe on my wife's 1995 Honda Accord EX. Here is how I got them
off:

1) liberal dose of PB blaster. 2) put on a small nut-cracker that I got
from Autozone for 8 or 9 bucks. I torqued the nut-cracker until the
chisel penetrated about 3/4 the way into the nut so I wouldn't hurt the
bolt. I think this process deformed the nut just enough for the PB
blaster to work its way into the threads. 3) finally, I put my ratchet
on there and the nuts broke on the second or third hit with a hammer. I
know hitting the ratchet handle with a hammer is likely to ruin the
ratchet, but I didn't have a breaker bar and the ratchet still works.

An interesting side note, it seems that the nuts are not 13mm or 14mm.
They seem to be somewhere in between, as the 13mm didn't fit over the
new replacement nuts, and the 14mm had some slop in it. I also tried
standard sockets without an exact match. Perhaps they purposely do this
so the 14mm socket will "always" fit over the nut even if it is rusted.
I guess this is a good design, especially if you are using an impact
gun.

Anyway, the job is done, and I saved myself about $100 by doing it
myself. Thanks again for everyone's input.

 

Nice update.

I tried one of the Autozone nut busters (with the chisel, to
be torqued into place) on a lower control arm castle nut
this past summer and got nowhere. Maybe my technique is
poor, though. The Autozone clerk warned me that it was not
guaranteed to work, and I could even bring it back.

I would be surprised if the OEM nut heads were non-metric.

My exhaust system has been worked over so many times (by
places like Midas) and then by myself, that most of it is no
longer OEM. I have had to disassemble the joint between
muffler and cat converter for other jobs a few times now.
Getting the bolts and nuts free is easier every time. I do
keep a tube of anti-seize handy, recognizing that
technically, the torque should be higher when using the
stuff.

 

Yeah, the Autozone nut buster ("OEM" brand) worked insomuch that I was
able to get the nut off. But it defintely did NOT "bust the nut"--at
best it dented it. The chisel also kept spinning around instead of
staying in a vertical position, which was very annoying. Fortunately
enough for me what it did manage to to do seemed to be enough for the
PB blaster to work, at least that is my theory.

 

Perhaps your sockets were not truly 13 or 14mm.
I have a couple of different socket sets,different brands,and the "same"
size sockets fit tighter or looser than the other,on the same nut.