Air suspension again

[sweeper]

So, since fixing the leaking line to l/h front all appears well with the suspension staying up overnight or several nights, but I have noticed the compressor to be running more often than I would expect it to, noticeable by the blow off sound as the pressure limit is reached and the compressor turns off, I suspect maybe another leak. this time on the line to the reservoir. So this morning I started it up and as expected the car didn't have to level and the compressor didn't run so it's not lost reservoir pressure overnight, I activated the rise function and the compressor started a second or two after the car started to raise and as expected it soon reached pressure and the distinctive blow off sound was heard, as it lowered there was a slight hiss as it started to lower and then quite quiet as it dropped to correct level.
It may be just that the vehicle is adjusting a lot due to temperature etc. and of course rising after high speed lowering, it's just odd as I didn't notice it previously. does anyone else notice this on the cars with Airmatic?

 

[RhodieBill]

I would say from my own personal experience is that if the vehicle is staying up - (average drop over 24hrs is +/- 2-3 mm) - overnight and longer but the Pump is running longer and also noisier more likely it is the Pump getting worn.
There is a Pipe running from the Pump to the Filter which can and from experience does split over time allowing in unfiltered Air into the Cylinder of the Pump damaging the Bore and Ring. This doesn't take long as it runs in a relatively dry environment with no lubrication.
It might be something to check and change the Filter while you're at it - a few of quid from Mercedes.

My damaged Pump due to split Pipe. The straight part is to the open air, the squigly length goes to the Pump, (where mine was split). And all this is under the car in front of the Front Wheel Inner Arch. I'm sure they could have located it in a better location!!!

Also you can see that the Filter had been installed the wrong way around! (And the car had a Mercedes FSH). Makes one wonder!

 

[sweeper]

well the pump is really quiet, you can barely here it as it only runs with the engine running, you just here it pfewf (not sure how to spell it) once it switches off, as I understand the valve to the reservoir closes and the pump vents to atmosphere thus allowing venting through the compressor to drop car if needed, I also assume when the car needs to lift the valve to compressor will shut and the reservoir will open allowing pressure to build in the valve block, as reservoir pressure drops the compressor will kick in opening the valve allowing pressure to build in the valve block raising the vehicle and refilling the reservoir, your filter maybe correctly fitted as the air passes both ways, each time it drops at speed it will vent through the compressor, either way it won't make much difference.

Anyway i intend checking this and also checking for leaks between valve and reservoir just becaiuse the area the pipe had worn thorugh travels the same route as the pipe to reservoir.

 

[RhodieBill]

The Filter, according the fitting instructions in the Box of the replacement, is supposed to be fitted with the Arrow on the Filter showing direction of Airflow, (to the Pump). The one I removed clearly shows the Arrow pointing in the wrong direction.

 

[sweeper]

In this instance it makes no difference which way round the filter is fitted as the air moves in both directions, all of the air that goes in also comes out via the filter. Also agree it seems more logical to point arrow towards compressor, my pipe was split and this is why I heard it so much, the hose and filter act as a really good muffler for the released air, found a damaged pipe to the reservoir also, The car isn’t sitting correctly and often raises one rear too high, so I’ve just fitted new rear level sensor along with an adjustable link of my own design with a stud with left and right hand threads, new ball ends etc I’ve set these at normal length ready for a calibration but that is not needed, I measured ride height using a app on iPhone and the rears are in spec ( I have access to a calibrated level surface) got the angle settings from wis the ride is much better but I still think the rear shocks are a bit thumpy on certain pot holes so maybe I need to replace them? Next though is to fit adjustable level sensor links to front and play a bit to see if I can lower it a little keeping the angles within spec as there is a bit of tolerance and give the car a better stance

 

[Oldspanners]

From what I can remember the air coming back to the pump shouldn't be vented directly to the atmosphere but is diverted back through the drying bed in the pump. It's explained somewhere on Youtube if I can find it again I'll post it.
As above check the pipe and fit a new filter it doesn't take long for grit to destroy a pump.

 

[sweeper]

Why is the pipe to the compressor so poor quality? I bet the one I fitted lasts forever. It’s a bit of old bctr hose I used to use as garden hose and is thirty years old at least, but it fitted and was all I had at the time

 

[RhodieBill]

I don't think you can honestly compare the pretty harsh environment that tube has to endure to your garden hose, even if it is left outside, which I doubt it is.....