C350e - Airmatic problem - four corners dropped

GTE

Hi all,

Seasons greetings to all. I hope everyone is having a great Christmas/New Year.

I am ending 2019 with a few problems; broken central heating, leak in the porch and now suspension problems with the wagon.

What Happened
I set off today and less than a KM of travel, about 50 metres after going over a speed bump I hear a crunching of front bumper on tarmac and then a red warning about the car being too low. I was able to pull over right away.


All four corners had completely fallen down. I then clicked the button to raise the suspension and this did not work. Forcing the engine on by going into charge mode and restarting the car didn't work either. I would always get a "Vehicle rising, please wait" warning on the screen. This was followed by the red "vehicle too low, stop" warning.


After five minutes, I started the car and immediately pressed the suspension raise button, before it had a chance to bring up the "Vehicle rising, please wait" message. Sure enough, the car raised and I was able to get it home. I parked up and I was able to cycle the suspension from normal to high a few times with no issue.

I then got back into the car a few hours later. With what little room I have in the driveway, I moved the car forward and then backward. I stopped the car with full brake with a hope to cause the issue again.

Sure enough, when I pressed the suspension raise button, the compressor kicked in but it struggled to lift the car, and actually dropped back down on all corners. After a cycling of the ignition, the car raised itself back up.

There does not seem to be an issue with the compressor. All four corners are dropping; I say this on the basis that a leak would only affect one corner at a time?

I'd appreciate any help before I send it on to a mechanic.

Happy New Year!

mullingar

Sounds like you have an air leak somewhere. Mercs are known for having premature failure of their air suspension bags in the shock absorber . Depending on the version, you could be looking at €1k in parts per air shock absorber

kirving

The car didn't drop after being off for a while, so that would suggest no leak.

On the other hand the compressor struggled to raise the car so something isn't right.

My E300 has auto-levelling rear airbags only, and one had a leak at the airbag. The anti-roll bar kept the car reasonably level so it wasn't noticeabe by eye really.

On mine, the left and right bags are linked, so the compressor jack's up the car, and a single valve releases pressure if it's too high (if I take load out of the car while it's running).

If you car is the same, and this valve became stuck open, it could cause the same behaviour?

I don't think the system will react to a ramp necessarily, and only sets the ride height when the car turns on, or a new height is selected.

Does braking cause a specific behaviour, or perhaps that's a red herring?


Edit: My airbag was in the region of €300, and took my mechanic all of 30 minutes to replace.

A crappy plastic clip that retains the top of the bag to the car has slipped out, and got caught between the plastic top of the bag and the car, and punctured the plastic top. I had noticed a rattling sound while driving over broken white lines, but the problem only became obvious after the car was off for a week at the mechanics and had lost a lot of air.

GTE

Thanks for the replies.

The car is indeed staying settled when parked.

After the initial suspension drop when I was going around the town, I got home and was able to cycle the suspension up and down and the pump did not sound like it had any issues.

This is me hoping, I admit; however, I would find it odd that all four airbags are linked. I'd have thought if one leaked, the other three would be okay to ensure the car is drive-able.

We are talking a very quick loss of suspension height here. The car had been parked for a couple of days, and there was no issue when I left. It all seemed to happen in the space of 50 metres.

The second time it happened, during my testing, it fell only when I asked the pump to raise the car. So, it seems to only happens when the compressor is active in some way.

This is wild speculation on my end!

GTE

Kevin Irving wrote: »

I don't think the system will react to a ramp necessarily, and only sets the ride height when the car turns on, or a new height is selected.

Does braking cause a specific behaviour, or perhaps that's a red herring?

The road was fairly consistently dropping and then raising. Not by amounts difficult to walk, but you can see the downhill stretch in the buildings. It was always slightly up or down hill. Perhaps it self levels in those instances.

I did hear the pump activate on the trip home, fearing the worst I pulled over. Nothing dropped but again, it was on a hilly stretch of the town.

The suspension first dropped as I went over the bridge.

The braking test I did was purely to jerk the car around, as I do not want to put it on the open road again.

kirving

bbk wrote: »

This is me hoping, I admit; however, I would find it odd that all four airbags are linked. I'd have thought if one leaked, the other three would be okay to ensure the car is drive-able.

We are talking a very quick loss of suspension height here. The car had been parked for a couple of days, and there was no issue when I left. It all seemed to happen in the space of 50 metres.

The control system in yours is certainly more complex than mine in that the front works too and you can set a height, but as far as I know, the left and right will still be linked on a single pressure relief valve.

Is yours an estate? I'm guessing here, but if it's an estate, it probably has separate valves for front and rear to allow self leveling for heavy loads. Again, pure guessing here, but the saloon could in theory has just a single valve.

Could also be an intermittent leak, but in my experience of pneumatics in automated machines (and these connections are similar), it that would be less likely.