Questions about Repairing My Exhaust

Hi, I have a '91 Chevy Cavalier 2.2L.

As I was installing a new muffler, my catalytic converter broke off where it
meets the front/head exhaust pipe, so I removed the catalytic converter and
middle pipe, which was still attached to it. So now I need to replace
everything from the cat back.

I have a few questions about my next move:

1) Is my front exhaust pipe still useable? Here are pics:

http://mallology.lunarpages.com/chevy-exhaust.html

The front pipe is in good condition, except for the flange where it meets
the cat.

Can I just somehow knock off the flange and put a new one over the front
pipe? Or is there any other way to attach the cat to the existing front
exhaust pipe?

I don't have a welder, except for a Sears Craftsmen oxygen-MAPP gas mini
torch unit. I will buy one if I have to. Should I buy a MIG welder?

2) If I have to replace the front exhaust pipe, is getting it off from the
exhaust manifold pipe hard? I took pics (see link above). Will I need to use
an Oxy-Acetylene torch to heat up the nuts (I have all the oxy-acetylene
gauges, torches, and hoses--I just need the tanks of gas)? Or will my Sears
oxygen-MAPP gas mini torch do? Is there anything I need to know? Like will
the studs break off?

3) How does the front exhaust pipe connect to the exhaust manifold pipe?
Once I take off the nut, does the spring just pop off? Is the stud welded to
the exhaust manifold pipe flange? What are the springs for? Where can I get
the new springs and nuts? PepBoys didn't have them last time I checked. Do I
have to go to the dealer?

4) What if the studs connected to the exhaust manifold flange are too rusty
to put the new nuts on? Do I then have to replace the exhaust manifold too?
I hope not!

Thanks for any help! And sorry for so many questions!

Julie P. wrote:

> Hi, I have a '91 Chevy Cavalier 2.2L.
>
> As I was installing a new muffler, my catalytic converter broke off where it
> meets the front/head exhaust pipe, so I removed the catalytic converter and
> middle pipe, which was still attached to it. So now I need to replace
> everything from the cat back.
>
> I have a few questions about my next move:
>
> 1) Is my front exhaust pipe still useable? Here are pics:
>
> http://mallology.lunarpages.com/chevy-exhaust.html
>
> The front pipe is in good condition, except for the flange where it meets
> the cat.
>
> Can I just somehow knock off the flange and put a new one over the front
> pipe? Or is there any other way to attach the cat to the existing front
> exhaust pipe?
>
> I don't have a welder, except for a Sears Craftsmen oxygen-MAPP gas mini
> torch unit. I will buy one if I have to. Should I buy a MIG welder?
>
> 2) If I have to replace the front exhaust pipe, is getting it off from the
> exhaust manifold pipe hard? I took pics (see link above). Will I need to use
> an Oxy-Acetylene torch to heat up the nuts (I have all the oxy-acetylene
> gauges, torches, and hoses--I just need the tanks of gas)? Or will my Sears
> oxygen-MAPP gas mini torch do? Is there anything I need to know? Like will
> the studs break off?
>
> 3) How does the front exhaust pipe connect to the exhaust manifold pipe?
> Once I take off the nut, does the spring just pop off? Is the stud welded to
> the exhaust manifold pipe flange? What are the springs for? Where can I get
> the new springs and nuts? PepBoys didn't have them last time I checked. Do I
> have to go to the dealer?
>
> 4) What if the studs connected to the exhaust manifold flange are too rusty
> to put the new nuts on? Do I then have to replace the exhaust manifold too?
> I hope not!
>
> Thanks for any help! And sorry for so many questions!
>

The studs should screw into the exhaust manifold and replacements are
readily available at any good auto parts store. (I'm actually surprised
Pep Boys didn't have them, even though they're not a good auto parts
store. They should be in the "Help" rack in blister packs, along with
new nuts and springs.) The tricky bit is unscrewing them from the
manifold without breaking them off, which will probably necessitate
R&Ring the manifold, thus leaving you open to the possibility of
breaking off studs in the head... you see where this is going don't you?
(don't feel bad, I just went down this road on my '55 Studebaker. You
are not alone <G>)

Should you decide that the flange is too bad to reuse... (really the
only way to tell is to try to bolt your new exhaust on and see if it
leaks. You have nothing to lose by doing this except for the gasket at
the front of the cat.)

Start soaking the studs NOW (both at the nut and where it screws into
the manifold) with a good penetrating oil such as PB Blaster, Kroil, or
Wuerth Rost Off. WD-40 ain't gonna do **** for you, don't waste your
time with it. Do it again every day, or twice a day if you can, until
you actually are ready to replace the studs. Try to loosen the nuts,
but if they don't give with a reasonable amount of force, don't try to
force 'em. Looking at your pics, it looks like the nuts are pretty
eroded by rust, as are the studs themselves. You may want to try to run
a die up the exposed threads on the studs so if the nut breaks free
before the stud breaks free of the manifold you can back the nut out
easily. Also you may need to use a deep socket of a size smaller than
the nominal size of the nut, and hammer it on for a good "bite." If it
should use a 1/2" socket, try a 12mm. If it should be 13mm, try 1/2".
etc. Use only six point sockets, 12 point sockets will only make your
life more miserable than it already is.

When the chosen day comes to actually remove the pipe from hell, use the
torch, Luke. Heat is your friend when it comes to exhaust fasteners.
It actually helps to have a helper at the ready with an appropriately
sized socket, extension, ratchet etc. (and some mechanic's gloves or
heavy leather gloves) to get right on that nut as soon as you move the
torch out of the way. Once you've got the pipe removed, if the studs
are still in the manifold, run a die all the way up and see if you've
got enough thread to give a good bite on a nut. If you don't, you're
going to have to repeat the torch process with the stud and some good
vice-grips instead of the socket. Heat the nut and/or manifold, as
appropriate, not the stud itself (although you can't help but heat it
up, concentrate your heat on the piece with the female threads.) When
the metal is glowing a dull red, that's when you act. I've also had
minor success when trying to remove studs from cast iron laying a cheap
candle on the metal and letting the melted wax "wick" into the threads
like a penetrating oil, and also with slapping an ice cube on the studs
immediately after removing the heat to "shock" the metal.

Now that you know how to get the pipe off, the question is, is it
cheaper to take it to a muffler shop and have them weld a new flange on
it for you, or just buy a new pipe? Call your FLAPS and get a price on
the pipe, it might be worth it to just replace it and save yourself the
hassle. You're probably going to have to go there to get new studs,
nuts, and gaskets anyway.

Since you're right there anyway and you're never going to have easier
access, consider replacing the O2 sensor, unless it was just done recently.

Do I need to say that on any exhaust job, LIBERALLY use anti-seize paste
on all fasteners to prevent future issues? It looks like the cat has a
bolted flange, I'd use stainless steel hardware there (with anti-seize,
of course - it's required for stainless even though it doesn't rust, it
can gall) if you can get it. Only gotcha is the O2 sensor - you should
use anti-seize paste on the threads, but be very careful not to get any
on the part of the sensor that projects into the manifold, that can ruin
in in short order.

good luck,

nate

(can you tell I love exhaust work?)

PS - this is what happens when you absolutely loathe exhaust work

http://home.comcast.net/~njnagel/55coupe4.html

$600 for the pipes, mufflers and clamps plus I had to replace my pass.
side exhaust manifold. But I will never touch the f'ing thing again.
(I've already replaced the one mild steel pipe in the pic with a
stainless pipe. The guy that made the system traded me even up for the
one I couldn't use even though the mix-up was totally my fault. Very
nice guy and you can see why I'm willing to pay his prices.)

--
replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel

"Nate Nagel" > wrote in message
...

> The studs should screw into the exhaust manifold and replacements are
> readily available at any good auto parts store. (I'm actually surprised
> Pep Boys didn't have them, even though they're not a good auto parts
> store. They should be in the "Help" rack in blister packs, along with new
> nuts and springs.)

Thanks so much Nate for such a detailed reply!

Yeah, they had those blister packs, but the counter wasn't too helpful in
finding the right ones for my car, nor was the info on the packs themselves
(either that, or the pack I needed was out of stock).

The tricky bit is unscrewing them from the
> manifold without breaking them off, which will probably necessitate R&Ring
> the manifold, thus leaving you open to the possibility of breaking off
> studs in the head... you see where this is going don't you? (don't feel
> bad, I just went down this road on my '55 Studebaker. You are not alone
> <G>)

does it stop at the head? Or is there any chance of the bolts getting
stuck in the engine block?

>
> Should you decide that the flange is too bad to reuse... (really the only
> way to tell is to try to bolt your new exhaust on and see if it leaks.
> You have nothing to lose by doing this except for the gasket at the front
> of the cat.)


Well, the holes/bores where the bolts would go on the existing flange are
open (look at pic 1 from my original link), so there is no way to securely
attach the cat. Unless I were to use nuts, and screw them on tight enough to
the remaining flange so the cat would not come loose? Part of the face of
the nut would rest against the flange then, and the other part of the nut
would be exposed. Would this provide for a secure fit?

>
> Start soaking the studs NOW (both at the nut and where it screws into the
> manifold) with a good penetrating oil such as PB Blaster, Kroil, or Wuerth
> Rost Off. WD-40 ain't gonna do **** for you, don't waste your time with
> it. Do it again every day, or twice a day if you can, until you actually
> are ready to replace the studs.

I was afraid you were going to say that! The problem is I drive this car
daily, so I need to get this fixed pretty fast, so I don't get run out of
the neighborhood for noise pollution.

Try to loosen the nuts,
> but if they don't give with a reasonable amount of force, don't try to
> force 'em. Looking at your pics, it looks like the nuts are pretty eroded
> by rust, as are the studs themselves.

If I got the nuts off, could I leave the studs on and just use new nuts?

You may want to try to run
> a die up the exposed threads on the studs so if the nut breaks free before
> the stud breaks free of the manifold you can back the nut out easily.
> Also you may need to use a deep socket of a size smaller than the nominal
> size of the nut, and hammer it on for a good "bite." If it should use a
> 1/2" socket, try a 12mm. If it should be 13mm, try 1/2". etc. Use only
> six point sockets, 12 point sockets will only make your life more
> miserable than it already is.
>

Thanks for this detailed advice! I'm wondering what would an exhaust shop
do? Do they worry about breaking the studs off, or do they use some sort of
trick?

> When the chosen day comes to actually remove the pipe from hell, use the
> torch, Luke. Heat is your friend when it comes to exhaust fasteners. It
> actually helps to have a helper at the ready with an appropriately sized
> socket, extension, ratchet etc. (and some mechanic's gloves or heavy
> leather gloves) to get right on that nut as soon as you move the torch out
> of the way. Once you've got the pipe removed, if the studs are still in
> the manifold, run a die all the way up and see if you've got enough thread
> to give a good bite on a nut. If you don't, you're going to have to
> repeat the torch process with the stud and some good vice-grips instead of
> the socket. Heat the nut and/or manifold, as appropriate, not the stud
> itself (although you can't help but heat it up, concentrate your heat on
> the piece with the female threads.) When the metal is glowing a dull red,
> that's when you act.

So I should do it at a dull red, and not wait for cherry/bright red?

I've also had
> minor success when trying to remove studs from cast iron laying a cheap
> candle on the metal and letting the melted wax "wick" into the threads
> like a penetrating oil, and also with slapping an ice cube on the studs
> immediately after removing the heat to "shock" the metal.

Wouldn't the wax drip down though to the ground, and not into the bore for
the studs? And wouldn't using ice only make the metal more brittle?

>
> Now that you know how to get the pipe off, the question is, is it cheaper
> to take it to a muffler shop and have them weld a new flange on it for
> you, or just buy a new pipe?

Is my current flange welded on (it is an original factory pipe form 1991!)?
Can you buy new flanges at auto parts stores?

Or could I just weld the cat to the existing front exhaust pipe flange? This
would seem a lot easier than risk breaking the studs in the exhaust
manifold.

I don't mind the challenge, it's just that I don't want to end up having to
replace the manifold and the cylinder head as well! And I want to be up and
running (quiet) again soon.

Call your FLAPS and get a price on
> the pipe, it might be worth it to just replace it and save yourself the
> hassle. You're probably going to have to go there to get new studs, nuts,
> and gaskets anyway.

Thanks. To me it's not so much the price that matters (I could just take it
to Midas and have them do everything for $400 I bet), it's more that I want
to learn to do this myself, and also know that it was done right. So I'd
rather invest the money in a MIG welder or something like that.

>
> Since you're right there anyway and you're never going to have easier
> access, consider replacing the O2 sensor, unless it was just done
> recently.
>

Is there any chance of that breaking off if I heated up the manifold?

> Do I need to say that on any exhaust job, LIBERALLY use anti-seize paste
> on all fasteners to prevent future issues? It looks like the cat has a
> bolted flange, I'd use stainless steel hardware there (with anti-seize, of
> course - it's required for stainless even though it doesn't rust, it can
> gall) if you can get it. Only gotcha is the O2 sensor - you should use
> anti-seize paste on the threads, but be very careful not to get any on the
> part of the sensor that projects into the manifold, that can ruin in in
> short order.
>
> good luck,
>
> nate
>
> (can you tell I love exhaust work?)
>

Thanks Nate! I wouldn't have know to use stainless steel. Can you get
stainless steel at Home Depot or other hardware stores?

> PS - this is what happens when you absolutely loathe exhaust work
>
> http://home.comcast.net/~njnagel/55coupe4.html
>
> $600 for the pipes, mufflers and clamps plus I had to replace my pass.
> side exhaust manifold. But I will never touch the f'ing thing again.
> (I've already replaced the one mild steel pipe in the pic with a stainless
> pipe. The guy that made the system traded me even up for the one I
> couldn't use even though the mix-up was totally my fault. Very nice guy
> and you can see why I'm willing to pay his prices.)
>

Very nice webpage! How did you lose all braking power? The Studebaker
doesn't have dual diagonal brakes?

And at least you have a paved surface to work on! I had to roll around in
the mud today!

Julie

Julie P. wrote:

> "Nate Nagel" > wrote in message
> ...
>
>
>>The studs should screw into the exhaust manifold and replacements are
>>readily available at any good auto parts store. (I'm actually surprised
>>Pep Boys didn't have them, even though they're not a good auto parts
>>store. They should be in the "Help" rack in blister packs, along with new
>>nuts and springs.)
>
>
> Thanks so much Nate for such a detailed reply!
>
> Yeah, they had those blister packs, but the counter wasn't too helpful in
> finding the right ones for my car, nor was the info on the packs themselves
> (either that, or the pack I needed was out of stock).

Ummm... yeah. I couldn't tell you either, never having worked on a GM
of that vintage. Hopefully someone more knowledgeable can reply.

>
> The tricky bit is unscrewing them from the
>
>>manifold without breaking them off, which will probably necessitate R&Ring
>>the manifold, thus leaving you open to the possibility of breaking off
>>studs in the head... you see where this is going don't you? (don't feel
>>bad, I just went down this road on my '55 Studebaker. You are not alone
>><G>)
>
>
> does it stop at the head? Or is there any chance of the bolts getting
> stuck in the engine block?

Eventually you'll get to the lug nuts <G> (BTDT... right now chasing a
tranny leak has me electrolytically derusting my heater assembly. Don't
ask.)

>
>
>>Should you decide that the flange is too bad to reuse... (really the only
>>way to tell is to try to bolt your new exhaust on and see if it leaks.
>>You have nothing to lose by doing this except for the gasket at the front
>>of the cat.)
>
>
>
> Well, the holes/bores where the bolts would go on the existing flange are
> open (look at pic 1 from my original link), so there is no way to securely
> attach the cat. Unless I were to use nuts, and screw them on tight enough to
> the remaining flange so the cat would not come loose? Part of the face of
> the nut would rest against the flange then, and the other part of the nut
> would be exposed. Would this provide for a secure fit?

Yeah, just use some thick flat washers. It looks like that was intended
to be a bolted connection to begin with, or else the threaded bit is in
the cat's flange not the pipe's flange. It really doesn't look THAT bad
to tell you the truth although I'd be tempted to try to smooth up the
mating surface with a flat file. If you have the cat already take a
look at that to see if those holes are tapped and if so you're going to
need to buy bolts to match those threads. If not you can use whatever
fits the hole snugly. (keep in mind for any rough hole size there's
going to be four different sized bolts - metric/SAE and coarse/fine
thread - that fit about right, but if the hole is tapped only one will
actually work.) I don't think the little slits on the outside of the
holes are any cause for concern, I believe those were there when the
pipe was made to allow for thermal expansion/contraction - you can get a
serious temperature differential between the pipe and the outside of the
flange when the cat really gets cookin'.

>
>
>>Start soaking the studs NOW (both at the nut and where it screws into the
>>manifold) with a good penetrating oil such as PB Blaster, Kroil, or Wuerth
>>Rost Off. WD-40 ain't gonna do **** for you, don't waste your time with
>>it. Do it again every day, or twice a day if you can, until you actually
>>are ready to replace the studs.
>
>
> I was afraid you were going to say that! The problem is I drive this car
> daily, so I need to get this fixed pretty fast, so I don't get run out of
> the neighborhood for noise pollution.
>
> Try to loosen the nuts,
>
>>but if they don't give with a reasonable amount of force, don't try to
>>force 'em. Looking at your pics, it looks like the nuts are pretty eroded
>>by rust, as are the studs themselves.
>
>
> If I got the nuts off, could I leave the studs on and just use new nuts?

maybe, maybe not. you won't know until you get there. But like I said
I would just try the pipe and see what happens. I think you'll be OK,
really.

>
> You may want to try to run
>
>>a die up the exposed threads on the studs so if the nut breaks free before
>>the stud breaks free of the manifold you can back the nut out easily.
>>Also you may need to use a deep socket of a size smaller than the nominal
>>size of the nut, and hammer it on for a good "bite." If it should use a
>>1/2" socket, try a 12mm. If it should be 13mm, try 1/2". etc. Use only
>>six point sockets, 12 point sockets will only make your life more
>>miserable than it already is.
>>
>
>
> Thanks for this detailed advice! I'm wondering what would an exhaust shop
> do? Do they worry about breaking the studs off, or do they use some sort of
> trick?
>

Probably they use an oxyacetylene torch - in skilled hands one can
probably burn enough of a busted off stud out that they can run a tap
through the hole in the manifold and reuse it. Of course the emphasis
is on skilled... in the wrong hands things can get ugly

>
>>When the chosen day comes to actually remove the pipe from hell, use the
>>torch, Luke. Heat is your friend when it comes to exhaust fasteners. It
>>actually helps to have a helper at the ready with an appropriately sized
>>socket, extension, ratchet etc. (and some mechanic's gloves or heavy
>>leather gloves) to get right on that nut as soon as you move the torch out
>>of the way. Once you've got the pipe removed, if the studs are still in
>>the manifold, run a die all the way up and see if you've got enough thread
>>to give a good bite on a nut. If you don't, you're going to have to
>>repeat the torch process with the stud and some good vice-grips instead of
>>the socket. Heat the nut and/or manifold, as appropriate, not the stud
>>itself (although you can't help but heat it up, concentrate your heat on
>>the piece with the female threads.) When the metal is glowing a dull red,
>>that's when you act.
>
>
> So I should do it at a dull red, and not wait for cherry/bright red?
>
> I've also had
>
>>minor success when trying to remove studs from cast iron laying a cheap
>>candle on the metal and letting the melted wax "wick" into the threads
>>like a penetrating oil, and also with slapping an ice cube on the studs
>>immediately after removing the heat to "shock" the metal.
>
>
> Wouldn't the wax drip down though to the ground, and not into the bore for
> the studs? And wouldn't using ice only make the metal more brittle?

The wax will get all over the place and make a mess (but hey, some
people are into that kind of thing) and yes the ice will make the metal
a little more brittle but it's already hot as heck and soft so you
weren't really going to crank on it anyway.

>
>
>>Now that you know how to get the pipe off, the question is, is it cheaper
>>to take it to a muffler shop and have them weld a new flange on it for
>>you, or just buy a new pipe?
>
>
> Is my current flange welded on (it is an original factory pipe form 1991!)?
> Can you buy new flanges at auto parts stores?

You probably can buy a new flange but it is probably welded on. You'd
likely have to go to a muffler shop to get just the flange though.

>
> Or could I just weld the cat to the existing front exhaust pipe flange? This
> would seem a lot easier than risk breaking the studs in the exhaust
> manifold.
>
> I don't mind the challenge, it's just that I don't want to end up having to
> replace the manifold and the cylinder head as well! And I want to be up and
> running (quiet) again soon.
>
> Call your FLAPS and get a price on
>
>>the pipe, it might be worth it to just replace it and save yourself the
>>hassle. You're probably going to have to go there to get new studs, nuts,
>>and gaskets anyway.
>
>
> Thanks. To me it's not so much the price that matters (I could just take it
> to Midas and have them do everything for $400 I bet), it's more that I want
> to learn to do this myself, and also know that it was done right. So I'd
> rather invest the money in a MIG welder or something like that.
>

heck yeah! I hear you there. But a good MIG will run you a couple
hundred bucks, and an angle grinder and a bottle of CO2/Argon mix is a
required accessory before you can do anything useful, along with
goggles, unless you're skilled enough to do "no-look" welding (and if
this is your first welder, you're not.) So this may be one of those
times where it's more economically reasonable to pass that up. That
said if you did have a welder and the flange really wasn't reusable, I
might try to repair it on the car like you're suggesting.

>
>>Since you're right there anyway and you're never going to have easier
>>access, consider replacing the O2 sensor, unless it was just done
>>recently.
>>
>
>
> Is there any chance of that breaking off if I heated up the manifold?

Not really. It gets rediculously hot in normal operation anyway. But
don't tempt fate by banging on it or anything. Actually don't even look
at it funny unless you are actually going to replace it. Murphy, ya know

>
>
>>Do I need to say that on any exhaust job, LIBERALLY use anti-seize paste
>>on all fasteners to prevent future issues? It looks like the cat has a
>>bolted flange, I'd use stainless steel hardware there (with anti-seize, of
>>course - it's required for stainless even though it doesn't rust, it can
>>gall) if you can get it. Only gotcha is the O2 sensor - you should use
>>anti-seize paste on the threads, but be very careful not to get any on the
>>part of the sensor that projects into the manifold, that can ruin in in
>>short order.
>>
>>good luck,
>>
>>nate
>>
>>(can you tell I love exhaust work?)
>>
>
>
> Thanks Nate! I wouldn't have know to use stainless steel. Can you get
> stainless steel at Home Depot or other hardware stores?

Usually yes although how good the selection is depends on the store. It
seems that they don't restock the stainless stuff nearly as often as the
regular Grade 5 stuff. I am lucky in that I live right near the
chesapeake bay and there's stores in Annapolis that cater to people who
work on boats. I buy a *lot* of fasteners at one of these places.
(about 90% of everything they stock is stainless or brass, and they
stock a lot of stuff.)

>
>
>>PS - this is what happens when you absolutely loathe exhaust work
>>
>>http://home.comcast.net/~njnagel/55coupe4.html
>>
>>$600 for the pipes, mufflers and clamps plus I had to replace my pass.
>>side exhaust manifold. But I will never touch the f'ing thing again.
>>(I've already replaced the one mild steel pipe in the pic with a stainless
>>pipe. The guy that made the system traded me even up for the one I
>>couldn't use even though the mix-up was totally my fault. Very nice guy
>>and you can see why I'm willing to pay his prices.)
>>
>
>
> Very nice webpage! How did you lose all braking power? The Studebaker
> doesn't have dual diagonal brakes?

HA HA HA HA HA HA HA! single circuit master cylinder, four wheel drum
brakes. Dual circuit master cylinders weren't introduced for another
couple years yet, and weren't mandated by law until sometime in the
mid-late 60's. Make sure the parking brake works, 'cause if the regular
brakes go that's all you got, short of sacrificing the transmission.

I'm toying with the idea of converting to a dual master, however, as
kits are available, as well as trying to decide if I'm going to keep the
(actually pretty good) drums or convert to discs in the front. We'll
see how much is left in the piggy bank after it hits the street.

>
> And at least you have a paved surface to work on! I had to roll around in
> the mud today!
>
> Julie

Ya know, some guys pay good money to watch that... can you say webcam :P

nate



--
replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel

"Nate Nagel" > wrote in message
...
> Julie P. wrote:


>
> Yeah, just use some thick flat washers. It looks like that was intended
> to be a bolted connection to begin with, or else the threaded bit is in
> the cat's flange not the pipe's flange. It really doesn't look THAT bad
> to tell you the truth although I'd be tempted to try to smooth up the
> mating surface with a flat file. If you have the cat already take a look
> at that to see if those holes are tapped and if so you're going to need to
> buy bolts to match those threads. If not you can use whatever fits the
> hole snugly. (keep in mind for any rough hole size there's going to be
> four different sized bolts - metric/SAE and coarse/fine thread - that fit
> about right, but if the hole is tapped only one will actually work.) I
> don't think the little slits on the outside of the holes are any cause for
> concern, I believe those were there when the pipe was made to allow for
> thermal expansion/contraction - you can get a serious temperature
> differential between the pipe and the outside of the flange when the cat
> really gets cookin'.

Ok, duh! I thought the metal was so rusted, that that's what caused the
slits/holes! Although if they were always there, I wonder how everything
stayed in placed (maybe the bolt heads rusted off, and/or the slits
gradually corroded and let the cat give way).

I just thought of this: I might be able to drill the old bolts out of the
existing cat, and reuse it. I would just need a new gasket and new
bolts/washers/nuts. Although it is an original cat from 1991, so might be
time to replace anyway. The middle pipe is still in good shape.

I also don't have the new cat yet, so I can't see if the bores are threaded.
My suspicion is no, since I replaced a cat for my Toyota recently, and there
were no threads.

>>
>>
>> If I got the nuts off, could I leave the studs on and just use new nuts?
>
> maybe, maybe not. you won't know until you get there. But like I said I
> would just try the pipe and see what happens. I think you'll be OK,
> really.
>

I'm too chicken! I am really worried that I would end up breaking the nuts
or getting in over my head. So I guess I will just try reusing the original
flange. Then welding if that does not work. Then only try replacing the pipe
if necessary.

>>
>>
>> Thanks. To me it's not so much the price that matters (I could just take
>> it to Midas and have them do everything for $400 I bet), it's more that I
>> want to learn to do this myself, and also know that it was done right. So
>> I'd rather invest the money in a MIG welder or something like that.
>>
>
> heck yeah! I hear you there. But a good MIG will run you a couple
> hundred bucks, and an angle grinder and a bottle of CO2/Argon mix is a
> required accessory before you can do anything useful, along with goggles,
> unless you're skilled enough to do "no-look" welding (and if this is your
> first welder, you're not.) So this may be one of those times where it's
> more economically reasonable to pass that up. That said if you did have a
> welder and the flange really wasn't reusable, I might try to repair it on
> the car like you're suggesting.
>

The thing is I already own lots of tools, including angle grinders and air
grinders/sanders. I now need just the bigger things, like air compressor,
welder, oxy-acetylene gas canisters, pressure washer, Sawz-All. I have a
lot of body repair to do anyway, like rusted out rocker panels, so I do need
to get the welder at some point.

>>
>> Is there any chance of that breaking off if I heated up the manifold?
>
> Not really. It gets rediculously hot in normal operation anyway. But
> don't tempt fate by banging on it or anything. Actually don't even look
> at it funny unless you are actually going to replace it. Murphy, ya know
>


funny.

>
> Usually yes although how good the selection is depends on the store. It
> seems that they don't restock the stainless stuff nearly as often as the
> regular Grade 5 stuff. I am lucky in that I live right near the
> chesapeake bay and there's stores in Annapolis that cater to people who
> work on boats. I buy a *lot* of fasteners at one of these places. (about
> 90% of everything they stock is stainless or brass, and they stock a lot
> of stuff.)
>

ok, good to know this. I'm near Philadelphia. Have to keep an eye out for
boat stores.

>> Very nice webpage! How did you lose all braking power? The Studebaker
>> doesn't have dual diagonal brakes?
>
> HA HA HA HA HA HA HA! single circuit master cylinder, four wheel drum
> brakes. Dual circuit master cylinders weren't introduced for another
> couple years yet, and weren't mandated by law until sometime in the
> mid-late 60's. Make sure the parking brake works, 'cause if the regular
> brakes go that's all you got, short of sacrificing the transmission.
>
> I'm toying with the idea of converting to a dual master, however, as kits
> are available, as well as trying to decide if I'm going to keep the
> (actually pretty good) drums or convert to discs in the front. We'll see
> how much is left in the piggy bank after it hits the street.
>
>>
>> And at least you have a paved surface to work on! I had to roll around in
>> the mud today!
>>
>> Julie
>
> Ya know, some guys pay good money to watch that... can you say webcam :P
>

No comment!

Julie

Julie P. wrote:

> "Nate Nagel" > wrote in message
> ...
>
>>Julie P. wrote:
>
>
>
>>Yeah, just use some thick flat washers. It looks like that was intended
>>to be a bolted connection to begin with, or else the threaded bit is in
>>the cat's flange not the pipe's flange. It really doesn't look THAT bad
>>to tell you the truth although I'd be tempted to try to smooth up the
>>mating surface with a flat file. If you have the cat already take a look
>>at that to see if those holes are tapped and if so you're going to need to
>>buy bolts to match those threads. If not you can use whatever fits the
>>hole snugly. (keep in mind for any rough hole size there's going to be
>>four different sized bolts - metric/SAE and coarse/fine thread - that fit
>>about right, but if the hole is tapped only one will actually work.) I
>>don't think the little slits on the outside of the holes are any cause for
>>concern, I believe those were there when the pipe was made to allow for
>>thermal expansion/contraction - you can get a serious temperature
>>differential between the pipe and the outside of the flange when the cat
>>really gets cookin'.
>
>
> Ok, duh! I thought the metal was so rusted, that that's what caused the
> slits/holes! Although if they were always there, I wonder how everything
> stayed in placed (maybe the bolt heads rusted off, and/or the slits
> gradually corroded and let the cat give way).

Bolt heads rusted off is my guess.

>
> I just thought of this: I might be able to drill the old bolts out of the
> existing cat, and reuse it. I would just need a new gasket and new
> bolts/washers/nuts. Although it is an original cat from 1991, so might be
> time to replace anyway. The middle pipe is still in good shape.

Sounds like a plan. Can you sight through the cat? If the matrix still
looks good I don't see why you can't reuse it. Shake it. Do you hear
anything rattling in there? (no = good) If the bolts go into threaded
holes and you can get a pair of vice grips on the stubs you may even be
able to back them out after heating with your torch, that way you don't
have to bother trying to drill them. Hopefully you have a tap and die
set so you can clean up the threads. If they are stripped, just go to
the bolt and nut idea. If you do use nuts, consider using brass - they
won't rust or gall, and if you have to disassemble them in the future
and the bolts/studs are rusted enough to make life difficult, you can
just burn the brass nuts right off with a torch. I know Studebaker used
brass nuts for both the manifold flanges and the carburetor base for
that reason, not sure if that caught on with any other mfgrs. or not
yet. There has been a trend in recent years towards all-stainless
exhaust systems right out of the factory, so in another 10 years someone
will probably google this discussion and laugh...

good luck,

nate


--
replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel

Nate Nagel wrote:

> Julie P. wrote:
>
>> "Nate Nagel" > wrote in message
>> ...
>>
>>> Julie P. wrote:
>>
>>
>>
>>
>>> Yeah, just use some thick flat washers. It looks like that was
>>> intended to be a bolted connection to begin with, or else the
>>> threaded bit is in the cat's flange not the pipe's flange. It really
>>> doesn't look THAT bad to tell you the truth although I'd be tempted
>>> to try to smooth up the mating surface with a flat file. If you have
>>> the cat already take a look at that to see if those holes are tapped
>>> and if so you're going to need to buy bolts to match those threads.
>>> If not you can use whatever fits the hole snugly. (keep in mind for
>>> any rough hole size there's going to be four different sized bolts -
>>> metric/SAE and coarse/fine thread - that fit about right, but if the
>>> hole is tapped only one will actually work.) I don't think the
>>> little slits on the outside of the holes are any cause for concern, I
>>> believe those were there when the pipe was made to allow for thermal
>>> expansion/contraction - you can get a serious temperature
>>> differential between the pipe and the outside of the flange when the
>>> cat really gets cookin'.
>>
>>
>>
>> Ok, duh! I thought the metal was so rusted, that that's what caused
>> the slits/holes! Although if they were always there, I wonder how
>> everything stayed in placed (maybe the bolt heads rusted off, and/or
>> the slits gradually corroded and let the cat give way).
>
>
> Bolt heads rusted off is my guess.
>
>>
>> I just thought of this: I might be able to drill the old bolts out of
>> the existing cat, and reuse it. I would just need a new gasket and new
>> bolts/washers/nuts. Although it is an original cat from 1991, so might
>> be time to replace anyway. The middle pipe is still in good shape.
>
>
> Sounds like a plan. Can you sight through the cat? If the matrix still
> looks good I don't see why you can't reuse it. Shake it. Do you hear
> anything rattling in there? (no = good) If the bolts go into threaded
> holes and you can get a pair of vice grips on the stubs you may even be
> able to back them out after heating with your torch, that way you don't
> have to bother trying to drill them. Hopefully you have a tap and die
> set so you can clean up the threads. If they are stripped, just go to
> the bolt and nut idea. If you do use nuts, consider using brass - they
> won't rust or gall, and if you have to disassemble them in the future
> and the bolts/studs are rusted enough to make life difficult, you can
> just burn the brass nuts right off with a torch. I know Studebaker used
> brass nuts for both the manifold flanges and the carburetor base for
> that reason, not sure if that caught on with any other mfgrs. or not
> yet. There has been a trend in recent years towards all-stainless
> exhaust systems right out of the factory, so in another 10 years someone
> will probably google this discussion and laugh...
>
> good luck,
>
> nate
>
>

I just went back and looked at your pics a second time and yes the
flange is rusted, those slits are larger than they should be. That said
unless it is completely screwed and/or you're like me and want
everything to be absolutely perfect, if you have doubts about the
ability of bolts to hold without slipping out of place, just tack weld
some thick flat washers to the backside of the flange.

I don't mean to be cold here, but you did say this was a cavalier. Now
you may be attached to this car, and want to drive it forever, but it's
never going to be a classic and nobody's going to make fun of you for
doing a "frugal" exhaust repair on it, so long as it holds together and
doesn't leak.

Were it *my* car I would probably replace the pipe, because I'm anal
retentive about my cars. BUT if you choose to do so be aware you are
running the risk of making more work for yourself by dealing with those
nasty, evil looking studs and nuts.

nate

--
replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel

"Nate Nagel" > wrote in message
...
> Julie P. wrote:
>
>> "Nate Nagel" > wrote in message
>> ...
>>
>>>Julie P. wrote:
>>
>>
>>
>>>Yeah, just use some thick flat washers. It looks like that was intended
>>>to be a bolted connection to begin with, or else the threaded bit is in
>>>the cat's flange not the pipe's flange. It really doesn't look THAT bad
>>>to tell you the truth although I'd be tempted to try to smooth up the
>>>mating surface with a flat file. If you have the cat already take a look
>>>at that to see if those holes are tapped and if so you're going to need
>>>to buy bolts to match those threads. If not you can use whatever fits
>>>the hole snugly. (keep in mind for any rough hole size there's going to
>>>be four different sized bolts - metric/SAE and coarse/fine thread - that
>>>fit about right, but if the hole is tapped only one will actually work.)
>>>I don't think the little slits on the outside of the holes are any cause
>>>for concern, I believe those were there when the pipe was made to allow
>>>for thermal expansion/contraction - you can get a serious temperature
>>>differential between the pipe and the outside of the flange when the cat
>>>really gets cookin'.
>>
>>
>> Ok, duh! I thought the metal was so rusted, that that's what caused the
>> slits/holes! Although if they were always there, I wonder how everything
>> stayed in placed (maybe the bolt heads rusted off, and/or the slits
>> gradually corroded and let the cat give way).
>
> Bolt heads rusted off is my guess.
>
>>
>> I just thought of this: I might be able to drill the old bolts out of the
>> existing cat, and reuse it. I would just need a new gasket and new
>> bolts/washers/nuts. Although it is an original cat from 1991, so might be
>> time to replace anyway. The middle pipe is still in good shape.
>
> Sounds like a plan. Can you sight through the cat? If the matrix still
> looks good I don't see why you can't reuse it. Shake it. Do you hear
> anything rattling in there? (no = good)

Well, it's sitting outside right now. I'll take a look tomorrow in the
daylight with a flashlight. My guess is that it's pretty shot, as are the
bolts. I remember there was some rattling and blockage about 4 years ago, to
the point the car was not driveable. I let it sit for 6 months and the
problem went away! So, I think I probably should replace it.

If the bolts go into threaded
> holes and you can get a pair of vice grips on the stubs you may even be
> able to back them out after heating with your torch, that way you don't
> have to bother trying to drill them. Hopefully you have a tap and die set
> so you can clean up the threads.

Another purchase I need to make! I have a cheap $10 metric set, but I just
can't seem to justify spending $80-$100 or so on a good set (tungsten?),
given how little I would be using it. Maybe once I get my air compressor?

If they are stripped, just go to
> the bolt and nut idea. If you do use nuts, consider using brass - they
> won't rust or gall, and if you have to disassemble them in the future and
> the bolts/studs are rusted enough to make life difficult, you can just
> burn the brass nuts right off with a torch. I know Studebaker used brass
> nuts for both the manifold flanges and the carburetor base for that
> reason, not sure if that caught on with any other mfgrs. or not yet.
> There has been a trend in recent years towards all-stainless exhaust
> systems right out of the factory, so in another 10 years someone will
> probably google this discussion and laugh...
>


very good idea! I think I will seriously have to find a boating store around
here. Dealing with rusted or seized nuts and bolts is always a pain. I do
always use anti-seize compound liberally though.

J.

"Nate Nagel" > wrote in message
...

>
> I just went back and looked at your pics a second time and yes the flange
> is rusted, those slits are larger than they should be. That said unless
> it is completely screwed and/or you're like me and want everything to be
> absolutely perfect, if you have doubts about the ability of bolts to hold
> without slipping out of place, just tack weld some thick flat washers to
> the backside of the flange.
>

Yeah, I am actually feeling much better about things now. I'm sure if I
tighten the nut enough, that should hold; otherwise, I'll have an excuse to
buy a MIG welder.

AutoZone has the cat in stock, but it will take a week or so to get the
pipe.

I'm wondering: AZ wants $60 for an Arvin cat with lifetime warranty, but
Advance Auto Parts and NAPA have them for around $140, with 5 yr warranty
(at least for Advance-theirs is a Walker). Are these more expensive cats
really any better?

I am asking since I have gone through two cheap mufflers in 4 years now,
although both were lifetime warranty. It's good to get the free
replacements, but having to replace them every two years is a pain.

Or maybe I am hanging the muffler wrong? It fit over the existing exhaust
pipe a good two inches and I clamped it tight, but I know my car originally
had a "counter weight" over the middle pipe, which rusted off in 1997.
Perhaps the lack of that weight is causing more stress to be put on the
muffler to middle pipe joint?

> I don't mean to be cold here, but you did say this was a cavalier. Now
> you may be attached to this car, and want to drive it forever, but it's
> never going to be a classic and nobody's going to make fun of you for
> doing a "frugal" exhaust repair on it, so long as it holds together and
> doesn't leak.
>

Oh trust me, my car is no beauty. The paint is all peeling off and there are
rust holes everywhere! The interior roof covering is falling down and you
can see the springs in the driver seat. Would make a good candidate for
MTV's "Pimp My Ride"!

> Were it *my* car I would probably replace the pipe, because I'm anal
> retentive about my cars. BUT if you choose to do so be aware you are
> running the risk of making more work for yourself by dealing with those
> nasty, evil looking studs and nuts.
>

You are right. Maybe once I get more experience I will be more willing to
take the chance and tackle bigger jobs. But I might actually be setting
myself for more work later on since the studs in the manifold may become
even more rusted and likely to break than if I replaced them right now.

J.

In article >,
"Julie P." > wrote:

> Hi, I have a '91 Chevy Cavalier 2.2L.

Answers in line...

> As I was installing a new muffler, my catalytic converter broke off where it
> meets the front/head exhaust pipe, so I removed the catalytic converter and
> middle pipe, which was still attached to it. So now I need to replace
> everything from the cat back.
>
> I have a few questions about my next move:
>
> 1) Is my front exhaust pipe still useable? Here are pics:
>
> http://mallology.lunarpages.com/chevy-exhaust.html
>
> The front pipe is in good condition, except for the flange where it meets
> the cat.

The flange has had it. No "ifs" "ands" or "buts."
Grab a Channel Locks pliers of suitable size and give the front
pipe a squeeze in various places, if there is any give, the pipe
is junk also. If the pipe proves sound, lop the flange off with
a hack saw (or buy a saws-all), cut it close as you can to the
flange, nice and clean and square. Measure the pipe outside
diameter and note it.
Take your old cat-con into the parts store, tell them you want
one long enough to accommodate the piece you lopped off in the
correct diameter to fit the front pipe. IOWs, there is nothing
that says you -have- to have the flange connection on the front
of the cat-con, a pipe on pipe slip connection will work fine,
you just need the cat-con to be a little longer to make up for
the part of the pipe that you cut off and to have a pipe inlet
instead of the flange inlet.

> Can I just somehow knock off the flange and put a new one over the front
> pipe? Or is there any other way to attach the cat to the existing front
> exhaust pipe?

Too much work for little if no gain.

> I don't have a welder, except for a Sears Craftsmen oxygen-MAPP gas mini
> torch unit. I will buy one if I have to. Should I buy a MIG welder?

Of course you should buy a MIG welder, but don't kid yourself
into thinking that you'll ever get a weld to stick to that rusted
flange. You can't weld rust, no way, no how so forget it.
Use the MIG for what god intended, i.e., broken bolt removal!

> 2) If I have to replace the front exhaust pipe, is getting it off from the
> exhaust manifold pipe hard? I took pics (see link above). Will I need to use
> an Oxy-Acetylene torch to heat up the nuts (I have all the oxy-acetylene
> gauges, torches, and hoses--I just need the tanks of gas)? Or will my Sears
> oxygen-MAPP gas mini torch do? Is there anything I need to know? Like will
> the studs break off?

It's gonna be a bi**h no matter how you slice it. You'll need an
oxy-acetylene torch to (first) heat the nuts bright red and
(second) to blow out the stud holes when (not if) the studs break
off flush in the manifold. Salvaging the original exhaust parts
on a 14 year old car is damn near impossible, do-able but like
Nate said, you better not mess up.

> 3) How does the front exhaust pipe connect to the exhaust manifold pipe?
> Once I take off the nut, does the spring just pop off?

Yup.

> Is the stud welded to
> the exhaust manifold pipe flange?

After 14 years, it is now.

> What are the springs for?

They allow the pipe to give and pivot as the engine twists in its
mounts. Other brands use an accordion type pipe that eventually
fatigues and needs replacement.

> Where can I get
> the new springs and nuts?

NAPA, CarQuest or any other -real- parts store. I buy them all
the time, they should be listed in the exhaust parts catalog.
NAPA shows the springs as part number 35281 and the bolts as part
number 35282, both are line code EXH.
BTW, I found those part numbers while sitting in my living room,
so PBBBBBTTTTT!!! to Poop Boys!

> PepBoys didn't have them last time I checked. Do I
> have to go to the dealer?

Probably obsolete at the dealer, any half assed parts store
should be able to cross reference those two NAPA numbers above.

> 4) What if the studs connected to the exhaust manifold flange are too rusty
> to put the new nuts on? Do I then have to replace the exhaust manifold too?
> I hope not!

No, there isn't anything that can't be torched out or drilled out
given enough patience and the correct tools.

> Thanks for any help! And sorry for so many questions!