A couple of weeks ago, the 280SL's power steering box started leaking. It quickly went from annoying to serious. The source of the leak was easy to find - the weep hole on the bottom cover of the pump as discussed in this post:
http://www.sl113.org/forums/index.php?topic=18777.0Here is how I fixed this leak. I did this repair with the box in the car, but for the pictures I used a spare box in the vise.
I ordered the seal kit from SLS as shown in the above post. With shipping, it was more than $60. I believe that the seals needed are as follows:
Small cover seal: 000 997 72 45
Large cover seal: 002 997 23 45
Recessed seal: 002 997 25 45
Optional steering shaft seal: 002 997 59 46
First, I suctioned as much fluid as possible out of the reservoir. I removed the Pittman arm (32 mm socket and puller), and the six screws holding the bottom plate on. The cover can then be loosened by gently tapping a small chisel or similar between the cover and the case. Have a large pan handy to catch the fluid and go do something else for an hour while the fluid drains. When the fluid stops dripping, the cover can be removed. The bottom of the box is shown in picture 593. Then the round cover to the left is removed with a pair of pliers. Now the fun begins.
The seal that is the primary culprit is inside the recess under the cover. See picture 595 which shows the recess and the seal removed. It needs to be removed with a dental pick. Here is the set of picks that I used:
http://www.amazon.com/gp/product/B00X9JE7LM?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s01The angled pick on the right is the one that worked best for me.
There are two problems. First, access to the seal is obstructed by the spring assembly. Second, if the seal is leaking, it has become hardened, making it very difficult to get under it with the pick. I ended up poking at it until it broke and finally came out. Putting the new seal in was much easier - coat it with a little silicon grease and tease it in with the pick. Then smear a little grease on the round cover (after cleaning it, making sure that the small hole is clear), and install it.
The two seals in the large cover are much easier. See picture 592. Remove the old seals. Clean the cover and put a little silicon grease on the seals and press them into the grooves. If desired, the steering shaft seal can be replaced by removing the snap ring and forcing the old seal out with a small screwdriver. The new seal can be pressed in using a 30 mm (I think) socket as a mandrel. Then install the cover, taking care to tighten the screws evenly. Finally, re-install the Pittman arm, nut, and cotter key.
Then fill the reservoir halfway with ATF and with the front wheels off the floor, gently turn the wheels back and forth, adding fluid as air escapes and the fluid level drops. Finally, start then engine and repeat the process until no more bubbles in the reservoir. Put the cover on the reservoir and you should be good to go.
