Air Suspension Repair - After action report

[DaHose]

Hello everyone,

I completed a repair of my air suspension, and I thought a couple of points were deserving of a write up.

To begin with, the problem started a few months back, where we noticed the compressor would run-on after we had parked the car. At one point, the right rear had completely collapsed, while the left held air. I tested with soapy water, and found no leaks on any lines or fittings, and after I pulled fuse 79 to reset the EHC system, things were working normally. That only lasted for about a week though, and then both sides completely collapsed. At that point, I could not reset and get air, so I tore into the whole system. I will also start by saying that I purchased a scissor lift this past summer. Without that lift, this repair would have taken at least twice as long. If you can make a lift fit in your work space/garage, DO IT!!!!

I don't have a ton of pictures, and honeslty I don't believe this thread needs them. If you are not capable of removing the bolts that hold on the cover for the air system, and replacing the compressor without explicit instructions, then you probably need to take your car to a shop.

The replacement compressor I ordered from Arnott came with a new air valve, new hoses, a new bracket, and with lifetime warranty.

e61aircompressor.JPG


You need access to the connection between the hose coming off the compressor, and the intake filter. That requires you remove the passenger rear wheel, and inner liner. I forgot to order a new filter, but my existing one was in great condition, so reused it. To mount the new compressor, I just removed a cover piece under car, directly below the battery area. The tools I needed were 1/4 ratchet, metric sockets (8 &10), and a 10mm wrench. Replacing things is really intuitive. Here is what you see when the cover comes off the underside, and in the wheel well.

e61aircompressorlocation.JPG e61compressorfilter.JPG

Mounting the pump was easy, and the new pump came with push-in style fittings. However, the original hoses had threaded connectors, and a bulge on the end meant keep you from slipping the connectors too far up. I cut the ends off the existing hose, right before the bulb end. That was easy enough to do with a shop knife. If your hose is straight, just take off the threaded fitting, and make sure there are no nicks in the hose. Cut some off if need be to ensure a clean surface.

With the pump replaced, I now needed to reset the EHC, and that is the big reason why I am writing this up. The Bentley book is the next best thing to the OEM shop manuals when it comes to understanding an E61. However, the Bentley tells you that the relay for the system is the one closest to the rear of the car. That was a bold faced LIE!!!! The Arnott pump came with a new relay, and the picture they included said the relay furthest from the rear (the light green one) was the EHC relay. By using my INPA laptop, I was able to run tests on the system, and figured out that the Arnott document was right. The green relay plug (circled in red) needs to be replaced with the one Arnott provides.

e61aircompressorrelay.JPG

The Bentley also says that fuse 79 is the EHC power supply, but 30 minutes of not being able to reset the EHC made me question that. I also realized I was getting a tire monitor system error. Poking around the fuse block, I discovered that the 40A fuse at position 72 was blown. That is when it dawned on me that fuse 72 FEEDS THE DAMNED COMPRESSOR!!!! GRRRRRR!!!!!!!! Stupid Bentley manual left that out! I figured that the motor must have pulled too much current when it seized, blowing the fuse. So if you notice that both your EHC and tire monitor went on the fritz together, check fuse 72. The picture below shows you fuses 72, and 79 (cirled in red).

e61aircompressorfuses.JPG

A final, tricky thing to know is that when the system fails, it could go into economy mode. That basically shuts things down, so you need to TURN OFF economy mode. You do that by firing up INPA, going to the E60 section, selecting the chassis functions, and working with the 1-way air system. Once I turned off economy mode, I tested and heard the compressor kick in. At that point I put everything back together, and lowered the car. When I turned on the ignition, the system inflated just fine, and everything seems ok now.

Considering that I was replacing the pump, the relay and the solenoid valve, I figured it was silly not to replace the air springs if they were affordable. Suncore sells the pair of bags for $110, but despite my ordering online on a Sunday, they took three days to process it. I will have to wait 1-1/2 weeks to get them. I pulled my air springs, and fortunately they didn't leak, so I put them back on while I wait for the new ones.

The big takeaways on this one are that the Bentley tells you the wrong relay, and that economy mode kicks in when the compressor fails. Just be sure you have access to an INPA system to test, and reset, and things should be fine.

Jose