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Secondary Air Components Replacement
 
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Pelican Technical Article:

Secondary Air Components Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$250

Talent:

***

Tools:

Sockets 13 10 mm, flathead screwdriver, plastic gasket scraper

Applicable Models:

BMW Z4 Coupe/Conv (2006)

Parts Required:

Secondary air pump, air valve and gasket, air hose

Hot Tip:

Replace any cracked or dry rotted hoses

Performance Gain:

Working secondary air

Complementary Modification:

Replace engine air filter

The secondary air system is used to improve catalytic converter efficiency and reduce the emission of harmful combustion byproducts in automotive exhaust. For a short period after a cold start, the catalytic converter is not hot enough to efficiently combine unburned fuel with available oxygen. An electric air pump forces fresh air into the exhaust stream just before the exhaust enters the exhaust manifold. This extra air supplies the catalyst with additional oxygen, thus speeding up the combustion of unburned pollutants and raising catalyst temperature rapidly. When the catalyst reaches what is called "light-off temperature" (approximately 400-600 degrees F or 215-315 degrees C) it is capable of self-maintaining a high temperature and the high efficiency of combustion. At that point the secondary air system may be shut off.

The secondary air system is prone to faults that illuminate the check engine light. If you have fault codes for your secondary air, check the operation of the pump. You can test the function of the secondary air components using a BMW scan tool. If you do not have access to one, you can check secondary air pump function when starting the engine. When a cold engine is started, the secondary air pump will run for a calculated amount of time. For more information on how to test the secondary air system, see our tech article on secondary air system testing. The check valve is the most common part to fail. In this tech article I will show you how to replace the secondary air pump and secondary air valve on the 6-cylinder S54 engine.

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.

The secondary air system is used to improve catalytic converter efficiency and reduce the emission of harmful combustion byproducts in automotive exhaust.
Figure 1

The secondary air system is used to improve catalytic converter efficiency and reduce the emission of harmful combustion byproducts in automotive exhaust. For a short period after a cold start, the catalytic converter is not hot enough to efficiently combine unburned fuel with available oxygen. An electric air pump (red arrow) forces fresh air into the exhaust stream just before the exhaust enters the exhaust manifold (yellow arrow). This extra air supplies the catalyst with additional oxygen, thus speeding up the combustion of unburned pollutants and raising catalyst temperature rapidly.

Working at the bottom of the pump, disconnect the electrical connector (red arrow) by squeezing the tabs and pulling it straight off.
Figure 2

Working at the bottom of the pump, disconnect the electrical connector (red arrow) by squeezing the tabs and pulling it straight off.

Next, you have to disconnect the secondary air pipe from the pump.
Figure 3

Next, you have to disconnect the secondary air pipe from the pump. Squeeze the collar (red arrows), and then pull the pipe straight off the secondary air pump to remove it.

Now it is time to unbolt the secondary air pump.
Figure 4

Now it is time to unbolt the secondary air pump. Start by removing the two 13mm nuts (red arrows) that secure the pump to the mounting bracket.

Lift the pump up with the mounting bracket to remove it.
Figure 5

Lift the pump up with the mounting bracket to remove it.

Place the pump on a workbench.
Figure 6

Place the pump on a workbench. Remove the three 10 mm nuts (red arrows). Then remove the mounting bracket from the pump. Transfer the rubber mounted over to the new pump (inset). Pull them straight off to remove it. Reverse the steps to install the new pump.

To replace the check valve, pull back the heat shield.
Figure 7

To replace the check valve, pull back the heat shield. Then disconnect the secondary air pipe from the pump. Squeeze the collar, and then pull the pipe straight off the secondary air valve to remove.

Next, remove the two 10mm nuts (red arrows) from the bottom of the check valve.
Figure 8

Next, remove the two 10mm nuts (red arrows) from the bottom of the check valve. I find it is easiest to do this using a ratchet with a 10mm universal adapter.

You can now remove the check valve from the cylinder head.
Figure 9

You can now remove the check valve from the cylinder head. Once removed, clean the sealing surface of the valve. Be sure to remove the old gasket (red arrow). Install the new secondary air valve with a new gasket and tighten fasteners. Then install the secondary air pipe. Check the operation of the secondary air components and clear the DME fault codes using a BMW scan tool.

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Page last updated: Mon 12/5/2016 02:53:56 AM