Loud clunking sound from rear when going over road turtles... ABC Valve Block?
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
Loud clunking sound from rear when going over road turtles... ABC Valve Block?
Took the S500 for a test drive; window open, enjoying life. When going over road turtles (those yellow reflective markers) I noticed a loud sort of clunking from the rear (noticed on the outside of the vehicle, not the inside).
It doesn't always appear when going over bumps but road turtles seem to trigger it. It sounds a bit like loose heat shielding, but a cursory check didn't show anything like that.
I've also noticed the rear starting to sag slightly when sitting, but not all the way down, just more than it used to do.
Could this be a bad rear ABC valve block? Anyone have these specific symptoms? Anything obvious to check before I go through the chore of rebuilding the valve block (already have a kit handy)?
It doesn't always appear when going over bumps but road turtles seem to trigger it. It sounds a bit like loose heat shielding, but a cursory check didn't show anything like that.
I've also noticed the rear starting to sag slightly when sitting, but not all the way down, just more than it used to do.
Could this be a bad rear ABC valve block? Anyone have these specific symptoms? Anything obvious to check before I go through the chore of rebuilding the valve block (already have a kit handy)?
Out Of Control!!
Joined: Apr 2019
Posts: 11,993
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
clunks *over turtles only*
I have the exact same thing in the front specifically with those turtle reflectors...
I attribute it to compromised Sway Bar bushings.
I attribute it to compromised Sway Bar bushings.
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
Out Of Control!!
Joined: Apr 2019
Posts: 11,993
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
The old ones are built better, the new ones are all crap. There are like three manufacturers worldwide. They cost significantly more than flooded. If they run dead even once they're toast. They can't be revived through electricity, nor through fresh acid or water.
Out Of Control!!
Joined: Apr 2019
Posts: 11,993
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Cell balancing helps recover from deep discharge to some extent.
I find the Mercedes "drain while parked by CAN-B" to be abnormally aggressive at draining any type of battery flat. It's best to use a CTEK or equivalent float charger.
