1992 300TE Hydraulic Leveling Thump
 

Thump... Thump... Thump... A very rhythmic Thump. It's coming from the leveling valve. Replaced it. No difference. Any ideas? It's driving both me and the owner bat poop crazy.

Any ideas? Adjusted wrong? It just started on him out of the blue one day. If I disconnect the arm from the lever, and move the valve lever UP, it stops, but not far from the top limit of travel of the arm.

Google is a dead end, and the repair manual indicates that another valve should have fixed it... but, no.

Crickets? Nobody else has run across this issue?:confused:

Maybe air trapped in the line the pump is trying to over come? Swap out the SLS valve see what happens. also could be something with the pump itself not moving the fluid right. I assume the fluid is at the correct level and is the correct type of fluid? any one side sag more then the others?

Swapped out the SLS valve already as per my original post. No air in the fluid, fluid level directly between marks on dipstick, it sits level side to side, and has no excess bounce so the accumulators are good. SLS valve swap made no difference, and that's what the repair manual led us to believe would cure it.

Thanks for the thoughts, though. I'd think that if it were the pump, we'd hear it at the pump, too. We don't- just at the valve. Other than this stupid thump, the suspension is perfect.

is it RPM dependant or Constant?

Constant.

hmm.. does holding your hand on the supply line dampen the sound at all?

Nothing dampens the sound unless I move the lever all the way up to fill position. Then it stops, but the car is way high and the shocks creak.

Have you checked the pump output? does it surge or constant stream?

Hi
certainly sounds like cavitation hammer...could be blocked filter or other restriction in the pipework if not an air leak.
Does the thumping stop with the valve fully open the other way? Might help locate where in the circuit the restriction or leak is
cheers

I'm said customer.

Where is the filter? I'll check it.

And just as a quick tidbit...I don't think it thumps whilst driving; only idle. I *think*.

If you run the arm through 'F' and 'L', the thumping stops in those positions. It also seems to stop (as to be expected from that) with a heavier load in the back of the wagon.

When I had you rev the engine, it didn't vary the thump. Maybe under load driving down the road is different. I was under the impression that it thumped all the time, no matter what.

If it actually stops with a heavier load we may just need to adjust it! Compare the ride height with the specs in the manual and see if the car is high in the rear. I thought it was kind of odd that the rod was adjusted as short as it could go.

Oh, and to readers- this is a '4Matic', which I neglected to mention.

Meh...mixed it up, filter is on power steering, none in sls:o...well it has a screen in the reservoir, thinking back

There are 2 positions for the lever, for different model fitment iirc 201 or 124?

sounds like it could be adjustment

AHA, thanks, now we may be getting somewhere! Might be a few days before this can be addressed, but will def. report back!

The 124 goes in the hole at the end of the arm. The middle hole is for the 201. The smaller first hole is used to set the arm in it's neutral position. I used a 12 penny nail as I had some on hand, but you can use whatever you have that fits snugly in the hole. FSM says it is 4mm. AFAIR and I haven't been under the car for awhile, the adjusting rod is somewhere in the middle not at either end.

FSM 32-0501 Function Description