lyonsfin

I have owned a 2009 E350 4matic wagon for about 4 years. Purchased with 130k miles now 157k miles. The rear end has always sunken down evenly after a week or so and now sometimes drops overnight. Always evenly and always back up with 1.5 minutes (or less). Are the bags leaking, a hose leaking or a valve? Replace everything or convert to coil springs?

juanmor40

Have you scanned the car for any codes?

I would approach the issue with a budget in mind. Check for leaks:
1 - If it is a hose or a valve , just fix or replace. Done
2 - If it is an airbag, then you need to work out the total replacement cost: "how many bags + labor + unknown parts when replacing" vs "coil conversion plus unknowns"

It is always best to check for leaks and find the root cause, estimate cost and weight future costs vs convenience. You gain something with coil springs as well as you loose something --> your call

E55Greasemonkey

Put some Arnott bags in the rear. Avoid the cheap ebay/Amazon ones.

tjts1

Whatever you do don't buy Arnotts. There have been so many complaints.

E55Greasemonkey

Had them on my E55 for 3 years now, no problems and the back won't drop for weeks.

rodneypierce

I've also got them in the rear of my e550. They don't leak, and they work great. As long as you don't need the adjustable suspension, as mine has had a bad resistor since nearly new.

Onyxthecat

Unrelated to the airbag system, I had the Arnott coil over set for my wagon and the rear springs sagged 3". The fronts were fine but I could not get the car to be level. The "Engineering" team attempted to help resolve the problem but then ghosted me after I sent pics of the issue. Arnott makes decent airbag replacements but, DO NOT buy the coil kit. BC Racing FTW.

tjts1

Read the w220 forum. Arnott's airbag suspension engineering is just as problematic.

Do not buy Arnott.