Octan3

Hi guys, so I bought a car and the rear airbags deflate together at the same rate over a few hours. the previous owner took it to Mercedes and I read their story they diaged it to be the air block/solenoid and had done their soapy water test, they referenced a bulletin from Mercedes to say if rear axle airbags deflate to do a quick check of a few things and then replace the air compressor and air solenoid block. Well I replaced the block last night, all be it with an aftermarket one from amazon which has good reviews. Swapped it out and let the car fully air up. sprayed with soapy water all over the fittings, No air leaks found then parked it for the night.

This morning, again. Rear airbags were deflated.

I've owned the car a week and it's both of them together, ones not higher or lower, I don't suspect a leaking air bag/s.

Any thoughts on further diag and direction? Thinking what are the odds of it doing the same thing with a new block. Doubt somehow the cars computer is doing it?

EDIT/UPDATE: It was both rear airbags.

juanmor40

Keep testing with soapy water at different junction points after the air solenoid block.

There are hoses/connections for:
1 - Front air bags (if present)
2 - Rear air bags
3 - Reserve tank
4 - T-splitter at the back, see over the rear subframe

Anywhere there is a connection, there is a chance for a leak. Since both are deflating, I would definitely check the T-splitter.

Though not for your specific vehicle, here is someone's else summary for the W220 platform. The important part is the line of thought used to solve problems.

Octan3

Thanks! I didn't know there was a t splitter, I seen 1 line per air bag into that valve/solenoid. Block labeling them for each corner of the vehicle. Front end is good. Will check!

juanmor40

There are so many variations on the airmatic installation, that depends on platform and year.

But the common principle is soapy water and search for connections. Sometimes is at the top of the airbag where the hose comes in; however, for both to deflate both have to be damaged.. Unlikely in common situations, but possible.

ChrisHimself

12k a year avg x 9 years youre probably closing in on 100k when the first rear air springs go out. The air springs have less of a service life than the front struts so I think we have to inspect and listen for any air escaping. The amount of air escaping is pretty small though so you'd have to get lucky finding a physical anomaly it or unfortunately throw parts at it. The rear air springs are either easy and an hour if you have technical experience, or 3 hours a corner if youre paying for the job.

If it was the compressor you can usually hear it while it's on its last legs. Compressors tend to die prematurely when they have electrical faults, or they've been operating for so long trying to fill bags up that they physically melt. Then you'd be able to find this via Xentry. Mercedes dealer likes to sell them together as a unit cuz well, money but I seldom in my professional experience have to replace the pump and valve block.

Octan3

Thanks for the info guys! I'll do some further tests and check overs and report back what I find! I'm a HD-commercial truck mechanic however the previous owner of this car paid mercedes to diag it and they said the valve block, I figured hey since both appear to go down together, makes sense I guess.... But deff more to this story than that. Could very well be that both rear airbags are leaking coincidentally. Much like having a vehicle come in with both headlights out... you think everything but the bulbs but I have had for some reason the 1 time both bulbs were gone lol.

ChrisHimself

yeah if theres two people i don't trust when it comes to cars, it's the previous owner, and the dealership lol

the previous owner will tell me the dealership changed the battery and i'm looking at a 12 year old battery that stranded them every. single. time. another hilarious one is that they "just had the oil changed the other day" and the engine cooked off a full quart of sooty used oil, and their filter is crushed to bejeezus when i remove it so it'd been in there a while, and it is very, very difficult to crush a Mann filter.

the sooner you take over repairs for the car, the sooner you can enjoy the pleasantries of mercedes ownership. I have a huge soft spot for E550's. They practically cost as-much as AMG cars but have nicer interiors, comfort, and are easier to live with mechanically since they often share parts with the 350 series of cars.

Octan3

For sure, The fella showed me the dealer invoice so I figured id roll with it.

A lil update: I Clamped off/blocked the air lines not far up from the air solenoid which would then completely isolate the bags from it. (I should of done that first) and they both deflated over night still, deff an issue upstream. I did a quick visual on the airbag lines and did not see any sort of T, appears like a direct run from airbag to the solenoid though they run under some of the exhaust heat shielding. This evening I will plan to spray it with soapy water every where.

juanmor40

Octan3

Great video that fella made and he's super insightful.

Another update: Last night I Sprayed the lines down and the airbag fittings with very soapy water, could not see any leaks, I really paid close attention to the fittings into the air bags, again no air leaks. I clamped the lines again just before the airbags. Unfortunately they still deflated, Looks like I need 2 rear airbags.

Car only has 59k miles on her lol.

Aussie_E350_Wag

eBay has plenty of new bags for a fraction of the GENUINE cost, I've done one of my wagons rear bags and no issues for 12,000km so far for less than $200 I'm happy.

Octan3

thanks for the info! I'm glad to hear haha I by chance ordered an ebay set yesterday. I think shipped to my door around $220 canadian for both sides. Much better than $700 if they last. It Wont be here til around july 5th ishhh. Once I have them in and such I'll report back on how I made out.

Zynthe

We dont drive the same year E550, but which Ebay seller did you go to? I want to see if they have rear bags for a 2011.

Octan3

​​​​​​I looked up the oem part number then put it into the eBay, search, there's a few on there selling but they all look the same with roughly same prices, just went with a seller with high rep/sales.



Here the listing I bought from

https://www.ebay.ca/itm/Pair-Rear-Le...-127632-2357-0

Arrie

Which height do you leave the car parked, SPORTS or COMFORT?

In my car it caused a bit of confusion as sometimes rear of the car was all the way down but then at times it was not. I found out it depends on what height I left the car when I parked it. In SPORTS it went all the way down both side but in COMFORT it did not, just left side was all the way down but the right side was up some.

I think this behavior comes from the fact that in COMFORT mode springs are high enough to develop enough pressure in just one spring to keep the rear of the car from going all the way down when with SPORTS setting springs are too short for this and both sides go all the way down.

I think you have a leaking spring.

Octan3

Ive been driving it around in comfort mode. but in either mode it never made a difference, I did diag it to be both rear air springs, in a few weeks when they arrive I'll get them in and update the results

Octan3

Update:

The bags finally came in and I installed them last night. For the most part they were identical but the bottoms that go into the control arm was a bit different, all the youtube videos showed the factory ones had that ribbed moulded plastic maybe an updated design? however my factory ones had the plastic moulded smooth bottoms, these ones had the plastic ribbed bottoms. However the circular base that sits into the lower control arm was the same size there for its centered and wont move anyways.

So long short of that is they're fine.

Replaced them last night, quick drive then parked the car in the garage, came in this morning and they did NOT deflate... Yay... I'd say that's a battle won, Time will tell how long they last. I see no reason why they shouldn't last another 60k miles. a few people on FB have had them for years with no issues and mentioend they were identical to the arnotts anyways so who knows.

Arrie

Your car is coming to 10 years old or could already be 10 years old for the manufacturing date so the air springs to start leaking is a normal problem to have. You should go ahead and order the parts for front as they will go soon now, guaranteed!!! Better to change them out before the problems come...but you'll probably wait until they do leak...and tell us how you changed them out for the fix, right? These air springs do not go by mileage. They go by age that it takes for the rubber to dry rot and start leaking.

Our E-class is not that bad for the leak as you can drive the car with leaking spring. You just see the car down in the mornings, but it raises back up when you start it up. My S-class is different. I got a leak in front and the car dropped down and did not come back up. Hard to drive car like that but I did for 350 miles to get it home for repairs.

Octan3

Yeah I mean your not wrong on the age idea and the fronts, but if they did start to leak it'll be a small leak very likely like the rears, and yeah eventually rhe computer throws the fault and no longer bothers to air up, I had to clear the code 3 times or so the past few weeks to Driving it. I'll end up holding off and review it next summer,

pierrejoliat

Actually my dear friend, my 220 was only leaking from one rear airbag, the other just was incapable to hold the car up by itself, I don't know if the 212 is different somehow, but I had to watch the car closely to see the left was slightly lower first, then the car would sag down to even later, in my case on the 220, when it was going down overnight, I didn't get to see one side was going down ahead of the other, just saw both down until the leak got bigger, {faster}

pierrejoliat

In my case it was the leak was folded in sport, so it leaked more, in comfort, the bag was more inflated and the tear was flat.