Parts Catalog Accessories Catalog Tech Info Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Exhaust System Center Catalytic Converter Replacement
 
Bookmark and Share

Pelican Technical Article:

Exhaust System Center Catalytic Converter Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$200

Talent:

**

Tools:

13mm socket and wrench

Applicable Models:

BMW Z4 Convertible (2003-06)
BMW Z4 Coupe (2006)

Parts Required:

Exhaust system, exhaust mounts, gasket and exhaust clamps

Hot Tip:

Work with a cool exhaust

Performance Gain:

Replace worn muffler system

Complementary Modification:

Use performance muffler

The exhaust system wears out or rusts and becomes leaky with age. A leaky exhaust can be a severe health hazard to passengers if odorless CO or other exhaust gases find their way into the cabin. A leaky exhaust system is usually far noisier than an intact one. Finally, bear in mind that the catalytic converters and oxygen sensors, an integral part of any modern automobile exhaust system, are critical to the emissions control system of the vehicle. Generally speaking, a vehicle with defective exhaust system fails most annual state safety and emissions tests because of the safety hazard, excess noise and emission control failure.

A damaged catalytic converter or failed oxygen sensor mostly cannot be diagnosed visually. Before you remove the exhaust system, use a BMW scan tool or equivalent to download fault codes and determine if there is any reason to suspect the failure of these major emissions control components. The oxygen sensors, particularly those downstream of the catalysts, may be easier to remove once the exhaust system is off the car.

When removing the exhaust system and particularly if you are going to store it while other repairs are taking place, be sure to protect the oxygen sensors and their electrical leads. Do not drag the exhaust system on the ground carelessly.

On the BMW Z4, you can replace the rear center Y-pipe and the H-pipe with the catalytic converters. The mufflers can also be replaced separately as well as the front (warm up) catalytic converters.

This article will illustrate how to replace the center exhaust system with the center catalytic converters.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Raise and support rear of the vehicle on jack stands. See our Pelican Parts Technical Article on Jacking Up Your BMW.

On the BMW Z4, you can replace the rear center Y-pipe (purple arrows) and the H-pipe (red arrows) with the catalytic converters.
Figure 1

On the BMW Z4, you can replace the rear center Y-pipe (purple arrows) and the H-pipe (red arrows) with the catalytic converters. The mufflers can also be replaced separately as well as the front (warm up) catalytic converters.

Start by removing the rear body braces (red arrows).
Figure 2

Start by removing the rear body braces (red arrows). Remove the two 8mm fasteners (yellow arrows). Then remove the two 13mm Nuts (green arrows). Then remove the four 16mm fasteners (purple arrows). Support the braces as you remove the final fasteners and remove them from the vehicle.

Then, remove the exhaust support.
Figure 3

Then, remove the exhaust support. First, remove the four 13mm fasteners (purple arrows). Then remove the four 16mm fasteners (red arrows). Support the bracket as you remove the final fasteners and remove it from the vehicle.

To replace only the Y-pipe (red arrow), remove the mufflers, see our tech article on mufflers removing.
Figure 4

To replace only the Y-pipe (red arrow), remove the mufflers, see our tech article on mufflers removing. Then, counterhold the 13mm bolt (purple arrows) while removing the 13mm nuts (inset). These fasteners are always quite rusty on my area. I prefer to remove the exhaust as a unit, then separate the pipes.

To remove the front H-pipe (catalytic converters) or the entire exhaust as a unit, remove the four E12 Torx fasteners (red arrows), counterhold the 14mm nuts (purple arrows) when loosening them.
Figure 5

To remove the front H-pipe (catalytic converters) or the entire exhaust as a unit, remove the four E12 Torx fasteners (red arrows), counterhold the 14mm nuts (purple arrows) when loosening them.

Support the exhaust with a jack, use a block of wood between the jack and the exhaust.
Figure 6

Support the exhaust with a jack, use a block of wood between the jack and the exhaust.

Slide the front pipe toward the rear of the vehicle to detach it from the headers (red arrow).
Figure 7

Slide the front pipe toward the rear of the vehicle to detach it from the headers (red arrow).

Working above the muffler near the rear chock, remove the two 13mm muffler mounting fasteners.
Figure 8

Working above the muffler near the rear chock, remove the two 13mm muffler mounting fasteners. Support the muffler from below when removing. There is a 13mm fastener that runs through the mount (purple arrow), however this fastener is always rusty and easier removed with the exhaust out of the vehicle. Left side shown, repeat step for right side.

Working above the muffler near the center of the rear bumper, remove the two 13mm muffler mounting fasteners.
Figure 9

Working above the muffler near the center of the rear bumper, remove the two 13mm muffler mounting fasteners. Support the muffler from below when removing. There is a 13mm fastener that runs through the mount (purple arrow), however this fastener is always rusty and easier removed with the exhaust out of the vehicle. Left side shown, repeat step for right side.

You may have to wiggle the exhaust out of the exhaust manifold connections.
Figure 10

You may have to wiggle the exhaust out of the exhaust manifold connections. If stuck, raise the exhaust slightly. Then pull the exhaust off toward the rear of the vehicle (red arrow).

Once the exhaust has been removed, you can replace the front cats or repair the system as needed.
Figure 11

Once the exhaust has been removed, you can replace the front cats or repair the system as needed. Line up new parts with old, and mark where you will cut. Use a pipe cutter to cut the pipes. Then remove any sharp edges from the pipes. To replace the center mounts, remove the 13mm fasteners and replace with new.

Once the exhaust has been removed, you can replace the front cats or repair the system as needed.
Figure 12

Once the exhaust has been removed, you can replace the front cats or repair the system as needed. To separate the Y and H-pipes, remove the six 13mm fasteners (purple arrows). Be sure to install the pipe support (red arrow) when assembling, replace if damaged.

Install new parts using exhaust clamps.
Figure 13

Install new parts using exhaust clamps. Then reinstall the exhaust system. Be sure to replace the front flange gaskets (red arrows) and the flange fasteners if they are not in good shape.

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Privacy Statement]
 [Contact Us] [About Us] [Shipping] [Map to our Location] [Careers]

Copyright © Pelican Parts Inc.

Page last updated: Fri 12/9/2016 03:02:07 AM