Replace Pontiac Grand Prix Exhaust

Several years ago i was in a rear end collision and the entire back half of the car was replaced at a shop.  I didn't know at the time but they ended up putting back steel mufflers and exhaust, rather then stainless steel.  It wasn't a big deal until recently when they started to rust through.  First one of the support brackets rusted and i had to reattach it with some wire and JB Weld.  Then last week the whole back half of the exhaust pipe came off. 
remove muffler, remove exhaust pipe, pontiac grand prix

Luckily they didn't fall off the car, the rubber muffler brackets were still holding them on.  But i realized that i needed to replace everything.  Here's where the pipe broke.
how to fix a rusted exhaust pipe, how to fix a muffler

I took it to an auto repair shop and they quoted me almost $700 for parts and labor.  They said that they needed to replace everything from the catalytic converter back.  $700 seemed like way too much and i figured that i could do it myself.  When i started looking at prices for the parts i realized that $700 wasn't too crazy.  Some places online were selling entire exhaust kits for close to $700.  

The best deal on the internet though to get car parts is through Advanced Auto.  If you go to SlickDeals you can always find a rebate code for  $50 off of a $100 online purchase.  Last time i got really nice brake pads for less than the cost of the cheap ones.  So i ordered 2 mufflers and the exhaust pipe from them for around $210.  I had to get the resonator pipe from eBay because Advanced Auto didn't have the right size and i could get it cheaper from eBay.  I'll explain more about that size thing later.

Here's everything except the exhaust pipe, that came a day later.
muffler, resonator, auto zone, advanced auto, order online

Here's all the new parts laid out in the driveway.  You can also see that i had to buy a 2 1/4" to 1 3/4" pipe reducer.  When all the parts arrived i realized the first problem.  The muffler pipe and the exhaust pipe weren't the right size.
pontiac grand prix exhaust, repair, replace

Here's what it looked like with the car on the jack stands and wheel ramps that Karrie got me last Christmas.  The creeper dolly i got on clearance from harbor freight a few months ago.  There's no way i could have done this without these things.
car on jack stands and wheel ramps, creeper dolly

I also realized that i would need a bunch of clamps to connect all the pipes, at least 5 of them.  It wouldn't be a huge deal as long as there wasn't a problem with everything fitting correctly.  But since i always wanted to get a cheap welder from Harbor Freight, this was the perfect excuse to get one.  I went with the popular 90 Amp Chicago Electric Flux Welder.
harbor freight welder, cheap welder, 90 amp, flux
Using a coupon i got the welder for $90 and the auto dimming mask for $60.

It was a good thing i got it too, because fitting the pipes together was a bigger problem then i first thought and clamps wouldn't have worked.

But the first thing i needed to do was to remove the old rusted exhaust pipes.  The mufflers and part of the exhaust had already rusted and i just needed to remove them from the rubber rings.

Even with the ramps and jack stands there still wasn't a lot of room under the car to maneuver. 
room under car, fix, repair, pontiac, gm car

I only had to remove 2 bolts connecting the resonator flange to the catalytic converter pipe.  After spraying some PB Blaster to loosen the bolts, the first one came off alright.  But the second one wasn't budging.  I tried tapping it with a hammer as i wrenched on it but nothing.  So i went to the Sawzall.  After cutting the bolt half way through i decided to try loosening it again, this time it came off and i was able to remove all of the old exhaust.
remove resonator bolts, pipe, rusted, how to

There was a gasket between the resonator and the catalytic converter pipe, but they also used some sort of rubber sealer.  Luckily most of it came off on the old resonator pipe which i didn't need.
clean flange, car flange, bolts, exhaust pipe

Here's the other side of that flange from the catalytic converter, all cleaned up with a wire brush
resonator flange, wire brush, leak, loud noise

Finally i had all the old exhaust taken off the car.  Here's the old and new parts side by side.
new and old exhaust, gm, ford, chrysler, repair, replace

You can see that the old resonator is slightly smaller then the new one.  I knew that this was going to be a problem, i had ordered the resonator for a 2006 Pontiac Grand Prix and mine is a 2005. 
resonator pipe repair, replace

 The reason i did that is because all the people in the comment section for the 2005 part said it was too short and they needed an extender piece.  The part they received was 28", the 2006 part was 32".  So i figured i should order the longer one and cut it down.

So i marked the new pipe as to where i wanted to cut it.  I just used a hacksaw with a new blade to cut through the pipe.
size resonator pipe repair, measure, cut

The piece on the left is the larger pipe size that i needed.
fit resonator pipe size, weld

Now i could adjust the larger pipe a few inches to get it to fit, before i welded it.

how to size resonator pipe, fit

Then like i said earlier i needed to buy a transition pipe between the exhaust and mufflers.  Even then the pips didn't fit exactly, i had to use a grinder to get one side to fit in the muffler.
pipe muffler fit, reducer pipe, size, 2 1/4"

I needed to use the vice in the basement to hold the pipe while using the grinder.  I made sure to have a bucket of water handy in case anything started smoking or caught fire.
grind pipe metal, muffler part

Here are those flanges ground down to the right outer diameter.  But after i did a dry fit of everything i found out that they were a bit too long.  So the mark on the right is where i had to cut them to length.
auto zone transition reducer pipe,

Here they are cut, the pieces on the right are the ones i needed.

how to install a muffler on a car, steps guide

Then it was time to start welding.  I had never welded before, i just bought the welder that day.  But i had watch a couple of Youtube video's so i figured i was good to go.  I took about 3 minutes to practice on some of the scrap pipe.  The Harbor Freight welder only has a Min - Max adjustment for power and 1-9 adjustment for wire speed.  So after 5 practice welds i was ready to weld up the exhaust.

weld exhaust, how to

The first welds were to attach the transition pipes to the mufflers.  The pipe on the left is how it looks like immediately after welding and the pipe on the right is after cleaning the flux off with a wire brush.  It's obviously not great for my first weld, there were a few mistakes and i'm not sure that i used the correct power setting or wire speed, but overall it turned out better then i thought it would.
how to weld, muffler pipe, exhaust

The hardest part for me on welding is going the right speed.  It seemed like i was always going too fast and had to slow down to get a good bead.  But after a few minutes i had it all welded together.
2005 pontiac grand prix exhaust, GM

I had to flip it over a few times to weld on all sides.  Then before putting everything back on the car i made sure to spray lots of WD-40 on the rubber brackets.  These are what's used to attach the exhaust to the car.  They are rubber so the vibration isn't transferred to the frame.  The WD-40 made it easier to slide the brackets onto the posts.
wd-40 rubber flange, gasket, bracket, lubricate

It was a struggle to get it all back together, i had to use 2 milk crates to support the muffler end while i bolted the front back.  But eventually it all fit properly.
install new muffler, exhaust

So all in all i saved around $250 and ended up with a new welder at the end of everything.


Unknown said...

And a back up career as a mechanic...

Unknown said...

Those Walker mufflers you replaced have a lifetime warranty now. Hope they make them outta better material than yours.