SLS on 85 300TD not leveling
 

I sold an 85 wagon that has an excellent ride height, the accumulators have been replaced a couple of years ago but when weight is put in the back it does not level itself back out.

No leaks in the shocks. Do the pumps ever go bad? I sold the car and a mechanic in NJ is working on it. He says he has replaced the links for the valve in the back and it adjusted manually but it still would not level itself out manually with weight in the back.

Any ideas greatly appreciated!

If it levels out manually, the pump must be working. Sounds like it's something in the leveling valve itself. Did the mechanic have to push the adjusting lever out of its normal range to get the car to level manually? I don't believe the valves or rebuild kits are available anymore according to what I have read on here. Valve has o-rings that can be replaced.
I can't recall a post on a bad pump on here. Lots of other problems but not failing pumps to my recollection.

If the rear lifted when the mechanic manually moved the lever then the suspension valve is probably leaking like Kerry said. They are rebuildable. You have three options, buy a new one(lot-o-cash), buy a rebuild kit for the valve (~$125 for the kit only) from the dealer, or o-rings. I have all the o-rings you'll need to replace. If you need some let me know.

Are the valves and rebuild kits still available at the dealer?

I called the dealer a few weeks ago to find out if the rebuild kit was available and the guy said he could get one. It was well over $100 for the kit. I bought one several years ago for $75 and I thought that was expensive for the little tiny box I got. I don't know about the valve, I would assume you can get a new one. But it's going to cost an arm and leg.

If the linkage is removed and the wagon will move up and down with the lever, then the sag in the back is not being transfered to the valve. The valve lever is actuated via the position of the rear sway bar, so I guess the sway bar links could have an issue, something could be amiss with the sway bar "arm" to the valve linkage, or the linkage simply isn't adjusted short enough. I guess also the lever coming off the valve could have been mis-adjusted on the shaft that comes out of the valve. This is usually not supposed to be touched.
Shortening the adjustable linkage raises the wagon.....