Ralph - You may find something about this in the archives. I seemed to remember someone talking about driving a screwdriver into the front seal and prying it out then carefully driving in a new seal. I've copied a post that I found about that from the old original Mercedes Mailing List archives. The manual shows special tools to do this but there is often a good work around if one doesn't have the specific tool. I figured it would just be my luck to damage something using the screwdriver method so I decided to just dismantle and re-seal the pump on my '81 SL a few years ago. It wasn't too difficult of a task. Refer to 46-720 of the manual. The only problem I had was removing the big aluminum "closing" plug enclosing the volume control assy. I didn't have a wrench big enough and the metal that makes up the wrenching flats of the plug is rather soft and be easily rounded off. Don't ask how I know that. BTW, the closing plug is not available as a separate replacement part either, RATS! Actually there is probably no reason to remove the plug unless you need to clean out contaminants that may have found their way into the pressure regulator. So if your system is working OK, but just leaking at the seal, there is probably no reason to mess with the plug. Also, if you do decide to strip down the pump and replace all the soft parts, when replacing the back cover of the pump, even with lubing the O-ring really well, I had to use my dead blow hammer to seat the cover. I couldn't just push it home with my fingers. I thought I had something in the way or interfering for a while but finally decided it was just a tight fit around the O-ring.
Barry Re: Replacement of Power Steering Pump Radial Seal 500SEL Wolfgang Henke ([EMAIL PROTECTED]) Sun, 2 Mar 1997 15:44:51 -0800 I replaced the power steering pump radial seal on the 500SEL today. Comments are added below. Wolfgang > "Lewis A. Shadoff" <[EMAIL PROTECTED]> > With George Murphy's encouragement, I tackled this job today. > > The 126 Chassis and Body Service Manual indicates several special tools are > used (puller for the pulley, seal puller for the seal, seal installing > tool), but George said, "You don't really need them. You can make a seal > installer from some Saran pipe; you can get the seal out without the > special tool; you can get the pulley off." Well, he was right! > > Here's the procedure I used (based on the manual): > > 1) Remove the lid, compression spring and filter. (The innards of my pump > do not look like the photos. I have a plastic sleeve over the spring held > on with a 10mm nut) > > 2) Remove the oil with a syringe. I have a 50cc plastic syringe with a > short length of tubing on it to suck out fluids. (I have used an ear > syringe in the past.) I used an EZBleed vaccum pump (with 100 ml flask) which I also use to troubleshoot power door lock problems. > 3) Loosen the hoses. (17mm and 19mm open-end wrenches) > > 4) Loosen the nut on the pulley (7/8 inch wrench) You need to push on the > belts while loosening the nut in order to keep from turning the pulley. I used a 22 mm open wrench. > 5) Loosen the three nuts holding the pump. > > 6) Swivel the pump by means of the belt-tensioning screw to loosen the > belts. My pump was different from the photos. Instead of a gear on a > tensioning screw, there was a hex-head bolt which tensioned the belts. I > loosened it and removed the belts. > > 7) Remove the three nuts and remove the pump. In order to do this I had to > remove the charcoal cannister mounted on the radiator shroud to make room > for the pump to move forward. > > 8) Remove pulley. The pulley is made to accept the special tool. None of > the pullers I had would grab the slot. I used my 6 inch long 1/2 inch > drive extension and a plastic mallet, hitting the back side of the pulley > to drive it off the tapered shaft. Hit once and turn the pulley 180 > degrees and hit again. The third time it popped off. Now remove the > Woodruff key on the shaft. Judicious tapping with a screwdriver and > plastic mallet will get it out. I dont have any pullers and in order to get the pulley off I screwed the nut back onto the axis to protect the axle and then while holding the pulley and pump in one hand used a couple blows onto the axle with a metal hammer. Three blows and it came off. A plastic mallet would not get it off, blows seemed not sharp enough to break oxidation/crystals between pulley and tapered axle. I let WD-40 soak in before. > 9) Remove the seal. I made a tool to attempt this out of a cheap > screwdriver. I put the tip on an anvil and hit the end with a hammer to > bend the tip to a 90 degree angle about 1 mm from the tip. This can be > tapped into the seal to grab the inner metal part. I then hit the handle > of the screwdriver to pull out the seal. Well, the handle came off. So, I > bent the other end to 90 degrees about 1 inch from the other end, grabbed > it with pliers and tried hitting this with the hammer. It wasn't going to > come out that way. I tried this unsuccessfully as well. > I then just levered the screwdriver against the pump body trying to use > the 1mm tip to get the seal out. It went through the metal of the seal, > but it looked like the seal moved a little bit. I rotated the tool a > little to bear against a nearby section of the seal and levered again. > After doing some serious damage to the seal, it finally let go. You have > to be careful not to scratch the shaft or pump body where the seal goes. I poked a hole into the metal part of the seal and used a regular medium size screwdriver to level the seal out. Seemed easy that way. > The rubber parts of the seal were brittle and fell into many small pieces > some of which were in the cavity where the seal was. I cleaned this up > using Q-tips. Yes, the seal was brittle instead of pliable (rubber parts). > 10) Install new seal. I used a 1/2 inch drive 1 inch socket as a mandrel > and plastic mallet to drive the seal into the pump body. My 1 inch socket was not deep enough and also slightly larger than the outer diameter of the seal. Instead I simply used the old seal and two large washers together with the 1 inch socket to drive the new seal in. > I took this opportunity to clean the pump. I replaced the lid, put bits of > rag in the holes for the hoses and Gunked it and the pulley and hosed them > off and dried them. > > 11) Install pulley. Replace the Woodruff key and slip on the pulley. > Replace the washer and nut and tighten to 37 lb.ft. There is a place to > put a wrench on the pulley to hold it. I didn't have a big enough wrench, > so I used an adjustable wrench made to remove fittings for plumbing drain > pipes. > > 12) Install the pump. Slide the pump over the three bolts, replace the > nuts, tension the belts, and tighten the nuts. > > 13) Install the filter and tensioning spring, fill with oil. Start up and > turn the wheel from lock to lock to get out bubbles. Top up the oil. I forgot the purchase a new filter, mine needs replacement.. > Total time 2.5 hours. > > > > Lewis A. Shadoff BS, PhD, Lake Jackson, Texas -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Ralph W Sent: Saturday, March 31, 2007 10:40 AM To: Mercedes List Subject: [MBZ] 123 steering pump rebuild My pump in the '83 coupe is leaking out the shaft. Anyone done this rebuild? Is it as simple as getting a pully puller and pulling the pully and replacing a seal. I have an old spare pump but this is the second leaky pump I've encountered and would like a long term fix if it's easy to do. TIA Ralph W.
