strange noise before start

[scorpioy]

My car is 2009 3.5d. At random time, the car produce some noise as soon as I open the door before I start the car after overnight, from underneath the car, and last about 1 or 2 mins. I can't tell where exactly

Here is the video:
https://www.youtube.com/watch?v=OZhLZdFsIHg

The only thing I can guess is the air pump is doing inflation, but noise is not from the rear of the car. Can someone tell where this noise is from? Would this represent some premature failure? of the air pump?

Thanks

[mart_dev]

100% correct. The noise is from your compressor...which as it happens, is situated under the vehicle pretty much below the front seat.

If it is an ongoing thing (happens every morning you unlock the car) then it's a 99% chance your rear air springs have perished to some extent. Get them swapped out sooner rather than later.

[Xtony]

I don't have the air suspension and my X5 makes a noise as soon as I unlock it or open the door. I don't think it lasts quite as long as the noise in the video, so yours might be something different. I believe in my case, it might be a fuel pump priming.

[mart_dev]

If it is equipped with the third row seating option then it has rear self-leveling suspension...if not then I'm not qualified to say. Good catch Xtony, I'd hate to be leading the OP up the garden path because I never checked my facts.

[scorpioy]

Thanks guys. My car does have the 3rd row seats. The noise just last a few mins.

It happens maybe once in a few weeks. My question is, is this noise too loud or is it normal? If I change to a new air compressor, is it supposed to be less loud? I don't know if other people's e70 has the same behavior like this or not.

Another question is, it typically happens on a morning, after overnight cool down, why is car doing self-leveling at this time? Is this normal?

[mart_dev]

My experience was very similar (I too have 3rd row seating). It started pretty gradually with compressor engaging after an extended period of inactivity, typically overnight. Over a period of roughly 3 months it got progressively more frequent until at a stage it became very apparent that there was an air leak. As for the noise level, it sounds pretty standard on the video but that doesn't mean much I guess. From what I understand, if the compressor becomes noisy there is no doubting that there is something wrong since this is almost always as a result of a collapsed bearing (service technician's words, not mine). If you want to check for a potential leak it is very easy to do yourself although at the early stages of failure I believe it can be difficult to pinpoint.
It may help to mention that I was informed by an air spring supplier that the typical lifespan of an air spring is roughly 80-120 thousand kilometers.

[scorpioy]

Thanks mart_dev. My car is 81k km now.

How to check if air bag is leaking, as you are saying it's easy?

What parts have you replaced at the end? Air compressor and air bags?

What will the car behave after replacement of the air spring? Will the car run the air compressor only once in a few months?

[mart_dev]

Read Mujihads thread entitled REAR AIR SUSPENSION PROGRAMING near the bottom of the first page.

[ART-qitec]

OP, I urge you to take care of this right away. I had the exact same noise a couple months ago and my compressor went out while I was driving on the highway two weeks after I first started noticing the noise. This caused the rear to completely collapse and the ride was terrible and extremely bouncy/difficult to control.

The dealer recommended I change the compressor only but I went ahead and changed both the compressor and air bags as the bags have never been replaced and were only an extra $400 from my dealer. The compressor was $1100 FYI. If you were looking a lower cost option (noticed you're in Canada) you can go with Arnott. I copied the links below. The DIY was extremely easy and only basic tools are required. It took me about an hour to do with the help of my wife to guide the air springs into their slot. They also show a video on the installation for your reference.

Springs: http://www.arnottindustries.com/part...98_gid911.html
Compressor: http://www.arnottindustries.com/part...8_gid1042.html

[mart_dev]

If I may interject. Don't replace the compressor on the suspicion it may be faulty. Have a qualified technician take a listen to it first. It's neither cheap, nor is it considered to be a consumable, unlike the air springs which are ultimately going to fail at some point it every vehicle's life time. Much like conventional shocks need replacing. In the video you provided the sound seems to me to resemble any small, 12v air compressor (much like the ones most of us keep in the trunk of our vehicles for routine tire pressure correction). Unless it's running rough I wouldn't throw money at it. Like I said, get a professional to take a listen first. But definitely, don't leave it unattended.