The way I understood it, the Bilstein bellows are thinner and less susceptible to wear from their design. The bellows in remanufactured applications are thicker for being cross ply and will wear off more. Not sure if Bilstein implies more will equate to sooner/faster.

Putting my home engineering hat on here... maybe some lubricant applied to the outside of the bellow where it comes in friction with other components will help reduce wear. I am sure getting to the bellow will not be that easy and will likely void the warranty.

 

I'm pretty sure it's simply a matter of the radius over which it is bent and compressed. It's like running a tire when it's low on air - the excessive flexing of the sidewall can lead to failure.

Soaking the outside of the air bag with rubber preservative, e.g. Armor All?, might help but won't be a definitive fix.

 

I'm having almost the same issue as the OP: compressor running most of the time when driving around town. It stops when I come I come to a stop. I don't know if it runs at highway speeds since I can't hear it. I run Xentry diagnostics on the Airmatic system and the pump quickly reaches the 16 bar spec. I don't see any appreciable drop in any corner after parking for a while and monitoring all air springs and central reservoir pressures shows they are within spec with nothing loosing pressure rapidly that should call for the pump to be active most of the time. I've tested and replaced the pump relay with no change in behavior.

In reference to @Max Blast's quote above, why is the pump speed sensitive? I know the entire system is dynamic and it's supposed to adjust to driving and road conditions but Airmatic technical info I came across suggests once the bags are up to full pressure, the central reservoir should be enough to make those minor adjustments for dynamic driving conditions. So, it seems the only time the pump should really come on is to build up pressure to raise vehicle for more clearance, after it's been parked for a while, or after the height has been substantially lowered like after you've parked or open the tail gate; and of course after extended high way driving where the vehicle naturally lowers a bit for more stability. Why would a failing pump turn on almost all the time when driving at moderate speed if there is no obvious signs of major leaks? What is it compensating for?

I suspect the pump is indeed the problem since it looks original with 130k miles on it, but I'm looking for some rational explanation for this behavior. Rear bags have Arnott from previous owner and I replaced the fronts with Arnott 15k miles ago.

OP @Brent Castel, did you ever find the root cause of your problem?

 

The system only runs the pump when the motor is running, so as to mask the noise of the pump. Not sure about the speed sensitivity.

You should be getting Airmatic errors if the pump is becoming weak - that is, taking too long to fill the reservoir.

Conceivably you have a leak at the reservoir, so after the pump fills the reservoir, it leaks back down. The reservoir is very sturdy, however, and the lines aren't exactly weak.

Failure in the valve block usually consists of "I don't know what's going on" errors from the system. I think the actual term is "implausible".

At 130k miles, you ought to have a spare pump on hand anyway.

 

My speed sensitivity comment was based on empirical evidence of how my very noisy and weak pump would always shut off when coming to a stop in normal height mode.

I am not sure how it’s mechanized but I would assume to it is minimize noise at a stop and works through the Vss and the airmatic ecu, and would rely on the central reservoir to supply pressure for height adjustments while stationary. That is, Until the reservoir pressure trips the compressor back on line.

 

Thanks eric_in_sd and Max Blast. No error on the dash which would have been a welcome indicator at this point. This is a really odd behavior - sometimes the pump comes on for about one minute and then shuts off for a few seconds (~ 5 secs) and on again to repeat the cycle for a while until the duty cycle reduces or I give up and stop listening. It's worse after cold startup and it acts like there is a massive leak somewhere or the pump is very week, yet every Airmatic component test in STAR passes. The central reservoir can hold pressure according to STAR test and so do all the air springs and automatic leak tests. When I monitor the pressure in the individual air bags while driving I don't see any rapid fluctuation or pressure drop to suggest that the pump is topping it up. There is an faint ringing noise associated with the pump noise but that could be just vibration.

What is the compressed air going to? REALLY befuddled... It's too cold out to start pulling things apart for troubleshooting or manual leak test so I'm hoping whatever it is will last until later in the spring.

I welcome other ideas about where else to look.

 

Compressor.

 

sealant worked in the rear bags but not the front. I think the shape prevented much of the sealant getting down to the fold.

I’ve just replaced all four bags with Arnott due to one being destroyed in a FOD incident, but the problem hasn’t gone away. Front end dropping overnight, compressor running all the time and noisy. Just ordered the Arnott replacement pump. Will update again once it’s installed.

 

For some reason, I read that as “Inconceivable!”.