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Subject: Secondary emissions air pump replacement procedure Author: DavidC (moderator) : member since December, 2003 : 12931 posts Posted on: 2005-03-01 14:37:47

Symptoms
A loud noise from the front right side of the engine bay (a 1998 BMW 750iL with 67k miles), very much like a vacuum cleaner sound. The noise would start about 10 seconds after a cold start and last for approximately one minute. It was much more noticable from the inside of the car.

Solution
Replacement of the secondary air pump of the emissions system. See part #1 in the ETK diagram (emission control air pump). The pump is located behind the right (passenger-side) front bumper.

This article will show you, step by step with photos, how to remove the airbox, remove the front bumper and replace the secondary air pump.

Tools You'll Need
socket wrench
6mm hex screwdriver
6mm closed-end wrench
8mm socket
10mm socket
T50 torx bit
philips screwdriver
Secondary air pump (BMW part # 11 72 1 435 410), $330 after CCA discount from The BMW Store.


Start by removing the foglights. Insert a small screwdriver into the upper hole next to the inner edge of the foglight. Press inward to release the foglight.


Disconnect the wiring harness from the foglight.


Remove the two 8mm bolts in the front side of the front wheel wells. Repeat for the other wheel.


Carefully pry the plastic away from the edge of the bumper.


Remove the two screws from the plastic cover below the engine/bumper area.


Using a T50 torx bit, unscrew the bolts that secure the bumper to the frame. There are two bolts, one on each side inward of the foglights as shown.


Now the bumper can be pulled forward. It's helpful to have a second person as the bumper is large and somewhat unwieldly. If you have park distance control (PDC) sensors, they will have to be unplugged before completely removing the bumper.


Here's a view of the PDC sensor from within the bumper using a mirror. Disconnecting the wires is very difficult but, fortunately, removing the entire sensor from the bumper strip is easy. Just spread the two tabs holding the sensor and pull the sensor out (toward the rear of the bumper) of the hole. Each sensor only has enough wire to reach it's particular hole, so there's no chance of mixing them up during reinstallation. It helps to have a second person to pull out the sensor while one of you spreads the release tabs.


Pull the bumper completely off the car. If you have headlight washers (as we do in this car), just turn the bumper to the side so that we don't disturb the tubing for the washer system.


The object of our exercise, the glorious secondary air pump!


Remove the air intake tube.


Disconnect the two electrical connections to the air pump, then unscrew the hose clamp for the lower hose (standard BMW 6mm hose clamps).


Now remove the upper hose.


The bolts holding the secondary air pump to the frame are below the air filter box, so it must be removed.


Remove the two 8mm bolts as shown.


And the third bolt on the side.


Now the air pump can be lowered to access and remove the final hose clamp.


Slide the post out of the rubber grommet to complete the removal of the air pump.


A view of the new secondary air pump after installation.

Reinstall the air filter box, front air intake, PDC sensors (if you have them) and finally, the bumper. You're done! The entire procedure took about 3 hours.

David Cecil
Lexington, KY
Titanium silver '01 750iL, 92k miles
Oxford green '97 740iL, 184k miles
Alpine white '92 750iL, 95k miles (for sale)
Charcoal gray '86 735i, 101k miles (for sale)

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The 7 Series E38 Forum | Message Thread:

• Secondary emissions air pump replacement procedure (pic) (url) - DavidC 2005-03-01 14:37:47 (58958 views)
  • Don't forget to replace the EGR valves, too! (url) - DavidC 2007-04-27 12:48:45 (2159 views)
    • Do I have this on my 97 740il? (nt) - alexe 2009-09-03 16:28:39 (580 views)
  • More info in a followup thread found here. (url) - DavidC 2005-12-09 12:19:44 (1798 views)
  • Re: Secondary emissions air pump replacement procedure - mortyk 2005-03-01 20:42:45 (1845 views)
  • Nice! Any other symptoms like SES, check engine or the like and - Magnum 2005-03-01 16:02:59 (1587 views)
    • There were no other symptoms and the SES light didn't illuminate (yet) - DavidC 2005-03-01 20:49:41 (1671 views)
      • Interesting, because after this post I listened to my car upon start up - Magnum 2005-03-01 21:41:59 (1461 views)
        • Yes, a slight noise outside is normal, but not a loud noise that drowns - DavidC 2005-03-01 23:02:43 (1347 views)
  • Damn. That's the longest extension I've ever seen! - sealbeach740 2005-03-01 15:39:53 (1226 views)
  • Great write up! What is the purpose of this air pump? (nt) - silber98 2005-03-01 14:56:31 (1840 views)
    • Re: Great write up! What is the purpose of this air pump? - jbarton750 2005-03-01 15:46:41 (1996 views)
      • My Volvo has a similar pump... - txdarth 2005-03-01 18:45:50 (1552 views)
  • David, do the V-8 4.0 liter have this pump also? - Gary 2005-03-01 14:42:51 (1300 views)
    • Re: David, Great Article & Good Job!!! (nt) - HighLine740iL 2005-03-01 18:16:42 (1155 views)
      • Re: David, Great Article & Good Job!!! - 81xavieromar 2006-02-28 18:19:11 (927 views)

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