Hi there -

2006 W220 S65 with 100,000 miles. As it says in the title, the car will sag when left to sit. Sometimes overnight the sag will happen, other times it takes several days to a week. I know that sagging over several days/week is normal but it's the random overnight sag that has me scratching my head. No visible leaking fluid anywhere, no errors on the dash and the fluid itself has been regularly changed and filter replaced.

I'm looking to sell this car for a friend, but no way can it be sold if the ABC system isn't sorted. I'm comfortable working on these systems myself so any DIY suggestions are welcome!

thanks!

There's a TSB on this... I've posted it before... search ABC TSB... first step is change fluid and filter... as you've indicated, if it sags after a week no issue, overnight is an issue... what you've described is the valve block needing a rebuild (or replacement -- $1800 part, hence the rebuild)... the internal O-Rings need replacement after a while... could also be dampers passing nitrogen but more likely the block.

However, most people buying these cars used at this point know all of this... I think it's certainly worth new fluid and filter, but I don't know that I'd bother with replacing dampers and valve block for a car I'm selling... I'd just live with the price deduct.... if you want to keep the car it's worth fixing... if not it's just money... it's a 65 so ABC is the least of it's problems.

GL

maw

Thanks much! I have the TSB and did know about that. How can I tell if it's the front or rear valve block that's in need of a rebuild?

I'm comfortable doing the rebuild myself with the $75 kit from X8R Ltd (https://www.x8r.co.uk/). I'll be selling this car for someone else, so want to get top dollar for him

That's a good question... if it's sagging on the front driver it's one block, if on the rear driver it's the other... not sure which is which though... I didn't know it was Front v Rear blocks as opposed to Left v Right, so you're ahead of me on this... if after top dollar, then the fluid and filter should be done, as should the accumulators, as should the valve blocks, as should the ignition coils and voltage regulator... shall we continue?

Jokes. GL

maw

I assume nothing major changed from MY’03 to MY’06.

Front valve block controls both the left and right front shocks. The valve block is located in front of the left front wheel.

Rear valve block controls both the left and right rear shocks. The rear valve block is located in front of the left rear tire.

Sometimes you only see sag of only one corner, Eg only the right front. Then, your problem is in the front valve block, assuming the shock itself is not leaking. Sometimes you see both fronts leak down, which suggests the front valve block has more than one leaky solenoid inside.