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Exhaust System Replacement
 
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Pelican Technical Article:

Exhaust System Replacement

Nick Czerula

Time:

2.5 hours

Tab:

$200

Talent:

***

Tools:

Set of sockets, pipe cutter, flathead screwdriver, pry bar

Applicable Models:

BMW Z3 (1996-02)

Parts Required:

Exhaust system, Exhaust gaskets, Exhaust fasteners, Rubber exhaust insulators

Hot Tip:

Work with a cool exhaust

Performance Gain:

Replace worn exhaust system

Complementary Modification:

Use performance exhaust, replace oxygen sensors

The exhaust system wears out, 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 that form an integral part of any modern automobile exhaust system are critical parts of the emissions control system of the vehicle. Generally speaking, a vehicle with a defective exhaust system will fail most annual state safety and emissions tests because of the safety hazards, excess noise and emission control failure.

When replacing your exhaust system, you can remove or replace the front or rear sections separately. Once the exhaust system has been removed, repairs or modifications can be made. Keep in mind that a number of other repairs such as driveshaft replacement, transmission removal and fuel tank removal require that the exhaust system be completely removed from the vehicle.

Damaged catalytic converter or failed oxygen sensors generally 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 if 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.

To avoid marring the paint and trim, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying out body or interior items.

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 you're 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. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

When removing the exhaust system, have new fasteners, gaskets and rubber insulators on hand. These parts wear out just like the exhaust system and help to complete the repair.

Raise and support the vehicle on jack stands. If you raise just the rear, you should have enough space to work at the front of the exhaust. If not, raise the front of the vehicle to work on the front, and then raise the rear of the vehicle when removing the exhaust system. See our tech article on jacking up your vehicle.

Working at the center of the exhaust system, remove the fasteners that connect the front and rear sections (green arrows).
Figure 1

Working at the center of the exhaust system, remove the fasteners that connect the front and rear sections (green arrows). Be careful when loosening these bolts as they tend to break. I like to spray them with penetrating oil and clean the end of the bolt thread with wire brush before removing. I use a ratchet with a 12mm socket and a 13mm wrench.

This photo shows the bolts, one broken and one in reusable shape.
Figure 2

This photo shows the bolts, one broken and one in reusable shape.

Next, working at the rear of the exhaust, locate the rubber insulator at the left side of the muffler (green arrow).
Figure 3

Next, working at the rear of the exhaust, locate the rubber insulator at the left side of the muffler (green arrow).

Disconnect the rubber insulator from exhaust using a pry bar (green arrow).
Figure 4

Disconnect the rubber insulator from exhaust using a pry bar (green arrow). I spray the insulators with soapy water to help them slide off.

Next, working at the rear of the exhaust, locate the rubber insulator at the right side of the muffler (green arrow).
Figure 5

Next, working at the rear of the exhaust, locate the rubber insulator at the right side of the muffler (green arrow). Disconnect the rubber insulator from exhaust using a pry bar. I spray the insulators with soapy water to help them slide off.

The rear section is about ready to come off.
Figure 6

The rear section is about ready to come off. Now is the time to support it from below, usually under the muffler using a jack or jack stand. Once the exhaust is supported, use a flathead screwdriver to lever off the final rubber support at the inlet pipe to the muffler. Lower exhaust and remove from your vehicle. Be careful, the muffler is heavier than you think. If only replacing the rear section, install the new unit and tighten fasteners. If removing the complete exhaust system, continue following the steps below.

Before removing the front section of exhaust, you either have to disconnect or remove the oxygen sensors.
Figure 7

Before removing the front section of exhaust, you either have to disconnect or remove the oxygen sensors. If you want to remove them, see our tech article on oxygen sensor replacing. To disconnect, see the next step.

Pull sensor wiring out of mounting clips on heat shield (green arrows).
Figure 8

Pull sensor wiring out of mounting clips on heat shield (green arrows). Then disconnect electrical connector by pulling straight apart. (yellow arrow) Repeat these steps for the front oxygen sensor. Rear shown in photos.

Working at the front of the exhaust system, remove nuts that connect exhaust system to exhaust manifold (green arrows).
Figure 9

Working at the front of the exhaust system, remove nuts that connect exhaust system to exhaust manifold (green arrows). Be careful when loosening these nuts. I like to spray studs with penetrating oil and clean the end of the stud with wire brush before removing. Depending on your region, these can seize up. If they break, don't worry. You can remove the studs by hammering them out and replacing with new studs. You can see my vehicle has replacement bolts in place. This is OK too, as long as they are the tightened properly. Support exhaust system from below using a hydraulic floor jack or jack stand.

Now the exhaust support has to be disconnected.
Figure 10

Now the exhaust support has to be disconnected. If you are only removing the exhaust, remove the two 13mm fasteners from the bracket (green arrows). These are always easier to remove and do not break like the clamp side. Take note of the rubber insulator location before removing. If replacing exhaust, remove 13mm exhaust clamp fasteners (yellow arrows), then swing clamp down to open.

This photo shows the orientation of the rubber insulators.
Figure 11

This photo shows the orientation of the rubber insulators. The insulators should be between the two brackets and between the nuts and the bracket on the transmission (green arrows). Lower exhaust and remove from vehicle. You may have to wiggle exhaust out of exhaust manifold studs. If stuck, raise exhaust slightly, then pull exhaust off toward rear of vehicle. Install new parts using exhaust clamps then reinstall exhaust system.





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Page last updated: Fri 12/2/2016 03:05:53 AM