I have a 2014 W212 wagon that has been pretty flawless for the last 6 years with 190k miles. However it developed a weird symptom when sometimes it will lose the rear suspension air pressure while parked. Sometimes it will keep pressure for a week without even turning the car on, sometimes I come back to completely deflated shocks after a 30 minute stop.

I'm thinking it has to do with just which way the compressor stops as its intermittent and it affects both sides. Any idea what it could be? I am looking to DIY the solution but I don't want to buy a ton of parts...

 

Hey Greg, long time. Attached bulletin may apply.

 

Long time indeed!

I don't think my VIN ( WDDHH8JB5EA924144 ) is covered by the bulletin.

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May not be applicable for defective part(s), but certainly applies for pressure line(s) and moisture.

 

Are you saying if there is moisture they might goodwill it on a 190k mile car?

I guess only one way to find out. My fear is that I take it and they tell me I need to replace everything for $$$.

 

No, offering starting points to diagnose.

 

Got it! I was hoping this was a somewhat frequent issue, but looking at past posts it does not appear to be the case. Most people have it drop all the time, or it won't inflate at all, or it's just a small drop, but haven't seen many where it will retain pressure one week and lose it all the next.

guess I'm buying some leak detecting foam as a starting point. Thanks!

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I had an issue with my Airmatic that acted like what you explain. I just had it first in rear and then in front.

In don't know if your car has more than one level setting. Mine has Sports, Comfort and Raised positions. If I left the car over night in Sports (lowest) position I would find the car down on both sides in the morning but if I left it in either of the other two positions the car would not be down all the way. Just lower on one side.

This made it look strange but it really was not. The lowest position is so low that when one air spring leaks the other side goes down all the way with it because the spring does not have enough stroke to create enough air pressure in one spring to keep the car up on either side and it looks like both air springs leaked out but only one does.

I first changed the valve body hoping it had a valve seating problem as it looked acting randomly. Leak in a spring would leak the same way all the time was my thinking but new valve body did not help, After valve change I realized that the left rear air spring was the problem and went ahead and changed both. This fixed the issue.

And believe this same happened with the front air struts just a couple of weeks later. Fix was the same, i.e. replaced them and all has been good ever since.

If you have different level settings in yours do a simple test. Leave the car in lowest position and see if it goes down every time. Then leave it in highest position and observe what happens. If highest position does not go all the way down it would show one side slightly lower but still up. This would tell about spring leak or it also could be leak on tubing, valves or fittings, which is not very likely.

 

Since it’s a wagon, it should be much easier to troubleshoot with only the two rear air springs.

 

Another good thing to keep in mind is that the Air Springs for the rear of these are CHEAP CHEAP now... $125 on fleaBay for the pair and can be replaced easily.

Our wagon was sitting down on the right side so I ordered up a pair and replaced them in the driveway. This is a simple job and only requires a few tools. A Jack, lug wrench, 10mm open end wrench for the air line on top, Needle nose pliers to help remove the lower control arm plastic cover snap thingys, a large flat screw driver or small pry-bar, a decent sized hammer to bang upwards on the bottom of the plastic air spring base from below the lower control arm (a friction fit but they will be rusted in place haha) and a 2' carpenter clamp... the kind that has a pistol grip and can reverse the end so it works as a spreader bar to push the suspension downwards from the upper wheel well to make room to yank out the old airspring.

Before you rush to replace the airsprings though, test for a leak in the 4mm air lines (common) Start the vehicle and let the compressor build up pressure in the system. Shut the vehicle off then immediately listen carefully under the back of the wagon for an air leak. Hissss. The wagons don't have an air tank so this opportunity will be short. Have jacks ready to deploy to lift the rear vehicle if need be to better isolate the location of the air leak. Take the compressor dirt cover off as needed. Lower the vehicle off the jacks and repeat as necessary as many times as it takes to find the leak in the lines. I found a small pin hole leak in the 4mm air line under one of the black plastic Ty-wrap hold down supports about 10" forward of the compressor.

Bought a CHEAP CHEAP repair kit on Amozone for $11 that comes with hose and a bunch of couplings and connectors. Shazam, fixed for the next 80K miles.

"Tailonz Pneumatic Hose 4mm or 5/32 OD 2.5mm ID Polyurethane PU Air Hose Pipe Tube 10 Meter 32.8ft Clear "

 

FYI under further inspection, the leak was caused by the compressor cover pinching the 4mm air lines against the vehicle uni-body as they head towards the Air Spring. You can trim a slight "U" on the edge on the cover where the lines pass by so they don't get chafed there again.