Exhaust System/Exhaust Manifold Removal and Replacement
 

GrimmSpeed DIY Guide Series
Exhaust System/Exhaust Manifold Removal and Replacement
Updated 6/7/12

Click here to download this DIY in a printable .PDF format

Introduction: This guide will illustrate the basics of the BRZ/FR-S exhaust system as well as demonstrate removal and replacement of all exhaust components.

Tools: The tools listed below are suggested for this task. Optional tools are noted.
- Jack, jack stands or lift
- 3/8in drive ratchet
- 3/8in extension
- 14mm, 12mm, 10mm sockets
- 10mm deep well socket (optional)
- Phillips screwdriver
- 14mm wrench
- O2 sensor wrench

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Tips: In low-torque applications, we like to use long tools (extensions, deep well sockets, etc) to keep from busting our knuckles worse than we already do.

Procedure:
1. Begin by collecting your tools, safely jacking up your car and popping your hood. Consult your owner’s manual for preferred methods.

2. The first step will be to gain access to the entire exhaust system. This requires the removal of both panels below the car. We’ll remove the aluminum skid plate first. Use a flathead screwdriver, 10mm and 12mm socket along with your ratchet and extensions to remove six (6) plastic clips, four (4) 10mm bolts and eight (8) 12mm bolts. Use your screwdriver to pop the center part of each clip up about 1/4in before pulling the entire clip out. When you’re on your last bolt or two, be ready for the plate to fall. It’s not too heavy, but it can be sharp.

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3. Next, remove the seven (7) 10mm bolts holding the second underbody panel to the chassis. Set both aside.

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4. Now that the entire exhaust system is exposed, take a minute to identify each piece. Starting at the motor, the components of the system are exhaust manifold > crosspipe > forward midpipe > aft midpipe > axle back/muffler. The catalytic convertors are located in the exhaust manifold and forward midpipe. The forward midpipe also houses a resonator, not to be confused with the catalytic convertor.

5. These steps can be done in a number of difference sequences. We picked the one that seems to be the easiest. The first connection that we’ll loosen is between the crosspipe and the forward midpipe. Use a 14mm wrench to loosen and remove the two (2) bolts. Conveniently, there are weld nuts on the back side, so just be sure to put the bolts someplace where they won’t be lost.

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6. Next, remove the 14mm bolt holding the forward midpipe to its hanger.

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7. Using your 14mm socket and wrench, remove the two (2) 14mm spring bolts connecting the forward midpipe to the aft midpipe. Once these are loosened, they’ll no longer be in tension, so no need to worry about them flying away.


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8. Next, we’ll remove the muffler from the car. The muffler is held on by two (2) 14mm bolts and four (4) rubber hangers, one on each corner of the muffler. Start by removing the bolts and then remove the muffler from its hangers, one at a time. I find that twisting the rubber hanger off of the muffler is the best way to get it started. Be ready when you’ve got it loose, as the muffler is a bit heavy.
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9. Now that you’ve got the muffler and the forward midpipe off the car and set aside, removing the aft midpipe is as easy as pulling it off of its hanger and setting it aside as well.

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10. The exhaust manifold and crosspipe are the two remaining components in the exhaust system. We’ll tackle the crosspipe first. This smaller pipe runs over the subframe and is a bit tricky to remove. First, remove the two (2) 14mm nuts connecting the crosspipe to the exhaust manifold.

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11. Now that the crosspipe is loose, we’ve found it easiest to remove the heatshields from the pipe in order to snake it out without damage to the finish on the firewall and subframe. The heatshields are held on by four (4) 10mm bolts and a clamp with a single 10mm nut. Remove the fasteners along with the four heat shields.

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12. With the crosspipe shields removed, the crosspipe has room to be snaked out. It’ll take some trial and error, but trust me, it’ll come out. You’re going to want to pull back and up on the pipe while turning it slightly counterclockwise. We’ll be putting together a video as well that will help. Once that’s out, go ahead and set it aside.

13. The next (and last) step is to remove the exhaust manifold. This is actually pretty straight forward. First, disconnect the two O2 sensor wire connectors in the engine bay. You’ll also need to use a screwdriver to pry the tree clips free so that the sensors can be completely removed. Some people will leave these in and spin the sensors out with the wire still attached. We prefer not to stress the connections like that. For re-assembly, not that the longer sensor harness goes to the rear-most sensor and the connections are color coded

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14. Next, use your O2 sensor wrench or socket to remove both sensors from the exhaust manifold. If you’ve disconnected the harnesses from the car, this step is optional, as you’re able to remove the exhaust manifold with the sensors still installed.

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15. You’ll need to use your ratchet, extension and 14mm socket to remove the six (6) nuts. Be careful when you’re close to the end, as this piece has some weight to it. Once this is removed, you’re all done (or halfway done, at least).

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Closure: Reassembly or installation of aftermarket components will be just about the same as disassembly. As always, questions, comments and suggestions are welcome!

- Matt

Rockin. From the community to you. Thank you!

Excellent! thank you!:happy0180:

Big thanks guys! These guides will be a massive help to myself and others.

:clap:GrimmSpeed:clap:

Added this to the DIR Directory:
http://www.ft86club.com/forums/showthread.php?t=7365

you guys are too good!!! :thanks:

sticky this

Iloveyou

very helpful guide... thanks for sharing

Alright, so I've gotten almost everything off and I only have the crosspipe to go. I have one of the bolts connecting it to the manifold off and got about half way through on the other and now it will not budge (and the nut is starting to strip). Anyone have any advice?

I think u can try banging it or buying that spray thatll loosen it up. maybe some wd40? or some kind of lube? (lol)



Do any of these bolts have to be torqued a certain amount? should i just tighten it as much as i can by hand? have a torque wrench available but didnt see any number on here

Anyone have an answer? I tried looking in the owner's manual but didn't see anything at a glance

just tighten them by hand, but dont go extremely tight or they WILL break. trust me I know from personal experience :lol:

Yep I just learned that lesson from trying to tighten down the spring bolt on the mid pipe and front pipe. Now I have to rig it and hope the Subaru dealership have some on hand tomorrow.

What did you install a Header and front pipe? thankx for the right up/

For the front pipe, how much torque should be applied to the nuts?

Overpipe to Front pipe - 31.3 FT LB
Front pipe to Exhaust Pipe - 14.3 FT LB

What about header torque?

You're my HERO!!!! Thanks!

Having just done the header swap in my driveway, I have a note about O2 sensors

The rear sensor is easier to remove on the car with wire harness intact
The front sensor wire is easier to unclip and then remove sensor while header is off the car

Especially if you don't have a O2 socket handy

Thanks much for posting this DIY

what are the easiest way to take out the front flange bolt that connect to the overpipe? Its too tight, couldnt loosen it I try and no luck so far.. suggestion would be great. I'm installing my front pipe/test pipe from MOtiv Concept.

Problem solve

@GrimmSpeed, I found when putting in my manifold that I needed a deep socket 14mm to tighten down the header nuts, so that's a necessity. Never found a need for a deep socket 10mm in this installation.

Is the only way to install an over pipe seriously to jack up the engine?

NO! I was able to do it by taking the heat shields off first.. Check out steps 11 and 12.

^+1 take the heat shields off and it's easy to snake the OP towards the rear.

Sent from my SAMSUNG-SM-N900A using Tapatalk

We did get it out that way. I was asking about putting an aftermarket one back on. We did finally get it in without moving the engine.

Yeah. . aftermarket OP is even easier to install since you don't have to deal with the heat shields. Just have to twist it around until you get the right angle.

Well we had a hell of a time getting it in.

Anyone could tell me that the torque specs are for the header to head nuts? Thanks

I may be way off, but 22 ft-lb IIRC

That's what I thought, any difference if using a thicker gasket like the grimmspeed? Thank you though.

Does anyone know what type of bolts and nuts go into the stock mid pipe and axle back? I know that there should be four total but I don't know the exact measurements. Any ideas?

Dumb questions:

Not familiar with the connectors that lead to the O2 sensors. How do you disconnect them without breaking something? What do you squeeze or where insert flat head driver tip?

Is it safe to spray releasing agent on the O2 sensors while they are still in the exhaust manifold and remove the sensors with an open wrench (without contaminating the sensor tips)?

Thx

Check what size the O2 fittings are and buy a socket made for removing them. They have a slot for the wire to go through. A wrench might not be enough to get them out, but you can try it first if you want.

Thanks, via Google search if O2 sensor socket is necessary a lot of people said the got away with an open wrench.

Still prefer not to risk breaking the wire connectors if anyone can tell mw what you do to disconnect them.

It's just like any other connector.
You push the tab down and pull.

Tab on the top? With a screw driver?

Screwdriver or your finger. Whatever is easiest.

Just figured it out. Push down on the ribbed tab on top, out it slides. Sure beats breaking stuff.

Next challenge how to remove the cable tie down clips without breaking them. My gut feeling is push tabs together with screw driver.

I was so good at fixing solid state pinball machines. Lots of electro-mechanical stuff. Automotive is still a learning curve and I refuse to learn the hard way.