I am about to reseal a Vickers power steering pump on my 380sl. How easy is this job once I get the pump out of the car. Any special tools that I need?

DIY Resealing Vickers Power Steering Pump W124

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2012 E350
2006 Callaway SC560

I just did a leaking radial seal on my 400E. No special tools required for the job. Some of the mistakes that I learned from:

1. Mark the cam insert and pressure plate before you separate it from the front of the pump (the cam insert encompasses the daisy wheel and paddles). The pressure plate, shown in picture 3, sits on top of the cam insert and has that weird looking seal on it. It is only connected to the cam insert and front of the pump with two small pins and it may even come off as you separate the pump halves. The cam insert is actually sandwiched between the pressure plate and front of the pump. The two small pins have a groove on one end. Note which side goes through the cam insert towards the front of the pump and which side goes into the pressure plate. I think they are idiot-proof so as to prevent an incorrect installation anyway. Also, there is a directional arrow on the cam insert that should match the direction of rotation of the pump. You might be able to install this backwards, but MB may have made this idiot-proof too (good for me).

2. There are 10 paddles on the daisy wheel and some of them will fall out when you separate the cam insert from the daisy wheel if you are not extremely careful. You need to make sure the rounded edges (there are square and rounded edges on these paddles) go towards the outside so they run up against the inside housing of the cam insert. The square edges go toward the center of the daisy wheel, towards the radial shaft. If you get the paddles in backwards, you may have no power assist once you get it back together. I used a piece of cardboard and drew a circle with ten slots around it. I inserted the paddles exactly as they came off the wheel so I could get them back in correctly.

3. When you look at the front half of the pump there will be a radial shaft that the pulley mounts to and it will go into the front of the housing and will be retained at the back by the daisy wheel held in by a small c-clip (picture 4 shows the daisy wheel and c-clip with the paddles already removed). You may have some difficulty getting the clip off. I used a small screwdriver and found that it actually worked better than the c-clip tool from Sears. The Sears tool did work better on the reinstallation of the clip. Just get underneath one side of the clip with a small screwdriver and work it off. Once you get it off, you will be able to remove the daisy wheel and pull the shaft out the front. You can pry the old radial seal out with a screwdriver. I installed the new radial seal with a socket and hammer. Just note how far into the housing the old radial seal was installed so you put the new one in the same position.

4. Watch out for the pressure control valve which is inserted into the back half of the pump. (The second picture shows the back half of the pump with the retainer for the pressure control valve and spring.) The retainer clip holds a 4 inch spring behind it and it is under pressure. The clip will come flying off if you disturb it and the spring behind it will go flying across the room (ask me how I know). Pay attention to how the small retainer clip (a circular clip with 4 legs) is installed. If it's just the radial seal that's leaking, you may decide that you don't even want to take the control valve out. There are no seals in it anyway.

Here are some pictures I took of mine. Yours may be different--especially if it's a tandem pump. Make sure you check the repair manual for your specific model as it may be very different from mine.

Attached Thumbnails

         

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles