DIY owner mechanic replaces TD spheres

[Richard Eldridge]

Thanks to you guys here in this Forum, I diagnosed my 85 TD wagon's rather bouncy and un-Mercedes-like ride as a pooped set of spheres.

I replaced these without a serious hitch. It takes a 14 mm socket with a 8 to 12" extension and a rachet, a 17 mm box end and a 11mm flare nut wrench, which was not all that easy to find, but which I finally located at a Pep Boy's for $5.09 tax included. I bought a whole set of three these for $8.99, but it had only 8mm- 10mm, 12mm-14mm, and 17mm--19mm.

Each sphere is held on with three 14mm nuts screwed into lugs facing downward just forward of the axle.

Each sphere has a 17mm banjo bolt connected to a large hyraulic line and a smaller 11mm nut on a flared line that goes back to a modulator of some kind behind the axle that seems to equalize the flow to the hydro shocks.

To start, I removed all the oil I could, about a liter from the reservoir with a yardsale turkey baster, because I wanted to avoid getting all that oil leaked on me.

I bought two litres of fresh oil, and replaced about 3/4 of one l. The new oil was almost transparent, but the old stuff was about the color of log cabin syrup, and did not smell burnt or look very dirty.

The hardest nuts to remove were the 17 mm (or perhaps 16mm, the box end of my Thai-made wrench fit perfectly but the other open end seemed a bit loose. I clamped my trusty visegrip on the wrench and gave it a mighty tug and the bolt came free. It took about 20 minutes and a few choice words to convince the flare tube nut to screw in properly. I screwed it on by hand, but may have got it slightly cross-threaded on the first try. Or perhaps this was the work of some German or Turk in Sindelfingen

For some reason, the spheres were mounted with only one washer on the side with one hole and none on the other two. I put a new washer on all three lugs, since I felt that they might have been lost previously.

I filled the reservoir up and replaced the filter, and the car rose up as usual, but rides much better now. The bounciness seems to be gone.

The old spheres were marked 5/4, which I suppose means May 84, and the new ones were labeled mysteriously 09/03, which seems strange because it is July of 03 as I write this.

The hydraulic shocks were previously replaced according to the records that came with the car. It seems strange that they did not replace the speres at that time, but they didn't. They did bill the PO for two litres of hydro oil.

I suppose I could replace all the oil at a later date, but it really doesn't get hot or much of a workout. I did replace the filter, which didn't look too dirty.

To replace the filter, it will be helpful to know that it does not unscrew, but rather is hooked into a loop molded into the lid. To remove it, press the spring on the bottom toward the lid and unhook the wire eyelet on the end of the spring thingy from its loop.

The Haynes manual describes the hydro suspension on the rear of the wagon as dangerous and far to complicated for the DIY mechanic. I think they said this because they either didn't have a TD to play with or were just too lazy to try. These wagons are relatively rare.

Several colleagues have asked me whether it was a - (horrors!) a VOLVO wagon !!!

I imagine it could be dangerous to play with the hydro system if you were todisconnect the line with the motor running and the hydraulic pump working. I wouldn't do that. I even turn off the light before I change the bulb.

As I was looking at several of these wagons before I bought the best one I could find, I noticed that one had a broken shock and the hydro reservoir was missing. I think that if you overload these wagons and drive it over a rough road, you run the risk of breaking a hydro shock, which is why I decided to replace these spheres.


So thanks again to all of you for all the help in diagnosing the problem and replacing the spheres.