The entire right side of our 2006 R350 is sagging (3") compared to the left side (or maybe the left side is high?). The car does not have air shocks and a search here has come up empty.

Any ideas on what to look for?

The most common issue is the air spring on the rear to cause that sag.

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I've checked and we don't have the air spring suspension.

All R-class have rear air springs.
Fronts can be air-matic or steel springs.

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

There are no air lines running to it, nor the black air bag at the top. They all look just like normal shocks.

I'll take a picture and post it later tonight.

Edit: The dash says to check the tires and reset the Run Flat Indicator. All tires are good.

I stand corrected. It has the air springs.

I was thinking coilovers like the front.

A leaking air spring in the rear is the most likely issue.

Spraying warm soapy water on that air spring should show if there is any leaks.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I just got done diagnosing an '07 R-Class this morning! It's pretty straightforward. Remove suspect air spring. Carefully inflate w/compressed air. Hold underwater to verify leak.

You can try spraying them when they're installed, but I've found that the leak occurs under the fold, and may not be apparent. The fill n' dunk method has work best for me.

Thanks guys. My Plan was to soak the bags and associated parts with soapy water. If no leaks there, then look at the sensor, etc.

Well, I may need to take ILUVMIL's advice to remove and soak them, as I've soaked the right rear air spring with soapy water while the engine ran for 15 minutes and either didn't get the right spot or the air line is leaking before the air spring. I heard no hissing or air leaks at the air spring.

I could see the air line run into the sheetmetal above, but where does it go and where is the air spring compressor? I want to trace the lines from the compressor to the air springs

Had a thought last night. I need to support the control arm and possibly move the sensor to activate the air pump or valve to send air to the air spring.

Thoughts?

Pulled the air line off the bag, started the car and no air. Filled the air spring off my shop compressor and the bag filled up and held air. Manually adjusted the ride height sensor and air came out the hose.

Reconnected the air line to the spring and while adjusting the sensor, the spring filled up and held air.

Ordered a ride height sensor, so I'll pop that on and see what happens.

Well, I'm a little stumped.

Before replacing the ride height sensor last night, the right side air spring still held the air I filled it up from several days ago. It appears to work, but the car is still low on the right side after working on it.

Went out this AM and the right air spring was flat/no air.

Turned the car on and it pumped up, but not as high as the left side.

A few questions:
1- What causes them to bleed down? Leaks I know, but it held air for several days. Is there a check valve?
2- What is the height of the rear fender lip after starting and no load in back?

Maybe I need to bleed the left side and have it fill both at the same time.

Thoughts?

Little pin hole in the bladder.

That is why it was suggested to remove the air spring & inflate under water.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I understand the soak it in water test, but it held air, was firm and unchanged for 3-4 days. It then went completely flat in 9 hours overnight after the sensor changed and the car started. I checked it again right before I replaced the sensor to make sure. A soapy water test showed no bubbles after several hours.

Would a pin hole leak not let it fill up completely, yet leak down overnight? Seems like something would show over time and soapy water.

That said, can I pull it off with out breaking the tabs at the top?