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?

__________________
hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

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.

__________________
1968 230S Automatic, Elfenbein
1975 O309D Executive Westfalia Camper Bus, Blau/ Weiss
1972 280SEL 4,5 Dunkelrot
1966 VW Type 34 "Grosser" Karmann-Ghia
1963 VW 1500 Variant Pearlweiss
1969 VW Variant Automatic, Perugruen
1971 VW Squareback Automatic, Clementine Orange
2001 E320 4Matic Wagon- Our belated welcome to the 21st century! Polar White
1973 280SEL 4,5 Sliding Roof "The Bomb", Dunkelblau.