How to: Replace Muffler 3.4l

Well my muffler broke off from the center pipe and I decided to replace the whole thing rather than have it welded back together. It was fairly rusted. Couldn't find a write up on here so here's how I did it. (Also posting this so you all can tell me what I did wrong.)

You'll need a new muffler, I ordered this one: Bosal 294-237 for the 3.4l 4x4 extended cab, federal emissions. Partsgeek.com shipped it USPS for just $15. Another site I tried to buy from wanted $120 to ship it freight.

You'll also need a new gasket for the connection to cat. Fel-Pro 61039 fit nicely even though is says 95-99 on package. A new gasket for the O2 sensor: Bosal 256-603.

You'll need new hardware to bolt the center pipe onto the cat. The old hardware on mine was so rusted and corroded I had to unbolt the cat, pull the whole thing out and cut the bolts off with a grinder. This caused some very slight damage to the exhaust mount bracket but had to happen.

The bolts I pulled out of the connection from the center pipe to the cat seemed to be M10 - 1.25 x 30 or 40mm with a 12mm hex head, 12 mm nut. The nuts from the O2 sensor were 12mm as well.
If you end up having to pull out the cat, those were M10-1.25 x 30 or 40mm with a 13mm hex (or maybe external torx?? see photo).

Tools:
A long handle ratchet or breaker bar
long (14") extension
12mm 6 sided socket
12mm combo wrench
pry bars in various lengths were very handy
Liquid Wrench
Propane Torch (optional, for stuck nuts)
Strong ratchet strap (very helpful for installing new muffler)

First, remove the bolts connecting the center pipe to the cat. You will likely need to apply liberal amounts of liquid wrench or similar as these tend to be pretty rusted/corroded. The heat shield above this spot can be bent out of the way to access the drivers side bolt, I still needed a long extension here.
(New bolts visible in this photo)

If this goes easily, this job will be a piece of cake. These (deez) nuts caused this project to take all day for me so hopefully this post will save you some time. If they're really stuck and you can't get them off after repeated soaks with liquid wrench, heating/cooling with torch, etc, it may be easier to unbolt the cat, remove the whole thing and cut them off.

Then remove the two nuts (12mm hex) holding the O2 sensor. No need to remove the wiring harness from the sensor, just tuck it up over the drive shaft to keep it out of your way. (don't go driving anywhere now)

Next, lower your spare tire if it's still under your bed, you'll need the wiggle room to remove the old muffler.

Then undo the five rubber mounts, these should be the last things holding on your muffler. A jack stand or two were very helpful holding the muffler while doing this step. One rubber piece above the end of tail pipe, two above the muffler, two by the cat.

Carefully pull the muffler and pipes out from between the passenger side wheels. Take deep breaths and go slowly.

Congrats! Your done with the hard part! Crack a cold one, the next step sucks.

My muffler was shipped USPS without a box, it was hilarious. The mail dude was not impressed as the thing extended through the cab to his dashboard. Unfortunately the damn thing had multiple shipping labels, inventory labels, etc. This step is optional but if you don't want all these stickers to burn off, get a bottle of goo gone and a plastic scraper and go to town. It took me an hour.

Now to install. If you had to remove the cat, go ahead and put it back on with a new gasket. It's the same gasket referenced earlier for the other end of the cat.

Now slide the new muffler assembly in between the passenger side wheels, carefully routing the tail pipe over the rear axle and parking brake cable. Pop your jack stands under it to hold it up where it wants to be. After this step you can go ahead and raise the spare tire back into place.

Reattach the rear rubber mount to the tail pipe.

Now bolt the center pipe to the cat. Don't forget to put the exhaust mount bracket back on at this point, and use a fresh gasket. Bend the heat shield back out to it's normal position. Attach the two rubber mounts to the exhaust mount bracket arms.

Next reinstall the O2 sensor with a new gasket and 2 x M10 - 1.25 nuts.

The last step puzzled me for a bit. The two arms from the muffler that connect to the rubber mounts are pretty close together and require quite a bit of coaxing to reconnect. If you're having trouble, use a ratchet strap connected to the muffler like so:
And routed up over the pin that holds the rubber mount to the truck. This will pull the muffler right where it wants to be. Anchor the far end of the ratchet strap to the drivers side leaf spring mount:
I suggest you use a pry bar to take some of the strain off the ratchet mechanism and to coax the arm the last little bit into place to get the rubber mount on. Lubricate the rubber with something and it will go on MUCH easier.

This is my first crack at a how to on tacomaworld. Hope you enjoyed and that this may save you some time and money.

 

Nice write-up!

 

Awesome write up. I have done you the honor of bookmarking it. I did not know that Asian Hardware pack was available. I just bought it from Amazon:

$29 General Maintenance Hardware Tech Tray (Dorman #799-305)

https://www.amazon.com/General-Main...1-fkmr0&keywords=dorman+value+pack+asian+cars