How to get back plate off power steering pump - PeachParts Mercedes-Benz Forum

rhodes2010 · #1 05-19-2006, 10:58 PM

I have the power steering pump out of W126 and W123.
Have pulley off.

All the listed instructions on this site say:
1. Remove back cover.
2. Remove pump guts.

I removed circular spring clip from back, but cover does not want to budge or come off.

I did tap on front of shaft thinking this would dislodge rear cover.

Can anyone advise to remove rear cover ?

Thanks.

TheDon · #2 05-19-2006, 10:59 PM

is there a seal? maybe if you rap on the joint with a flat head and a nice lil tap with a hammer.. and a tap not a bang

rhodes2010 · #3 05-20-2006, 12:57 AM

Oh... this is fun !

So a bump and a little turning with a chisel on the inside edge and it sort of pops out.

And I think I am done - but wait. THen I figure out how to get the next plate out (pain).

And finally - I got the vanes all out and have them carefully placed aside in the outer ring (keep the vanes in the same direction).

So - here I am pump housing basically empty.
I STILL CANNOT GET THE SHAFT OUT !!!
I thought the shaft comes out so I can pull the seal out.

Any thoughts ?
Do I just tear the seal apart with the shaft in ?

If so, why did the posts say to get it all apart first ?

Hit Man X · #4 05-20-2006, 02:40 AM

On my Vickers pump, there were two internal o-rings on the backing plate area. I used a big ol' C-clamp to compress it, then pop that retaining ring out. Believe me, this tested my wits BIG time.

I had no reason to remove the shaft, my front seal wasn't leaking (I planned to replace front seal) and after my PS pump ordeal (don't ask)... I will cross that bridge when I come to it. Better to leave it alone.

My SDL pump needs a rebuild but I haven't figured out how to remove it yet let alone tear one apart...

rhodes2010 · #5 05-20-2006, 11:17 AM

My pump worked fine, it was only the front seal that was leaking (a little).

All I need to do was the front seal.

Can someone advise as best way to remove the front seal ?
The shaft is still in.

Hit Man X · #6 05-20-2006, 02:07 PM

For the front seal you need a special tool to yank that pulley. I believe the member "strife" on here has one. I made a thread regarding it a while back and he offered to let me borrow the tool.

Once you remove the old seal, installation should be easy with a deep socket and tapping it into place...

rhodes2010 · #7 05-20-2006, 08:44 PM

The pulley is off, no problem there.
Putting seal IN, no problem there.

Would like a little advice on getting the seal OUT.

Hit Man X · #8 05-20-2006, 09:32 PM

Ooooo, I see now.

I know there is a seal puller shown on that braingears site, but I'd just use a pick to get it out versus purchasing that tool you'd probably use once.

kip Foss · #9 05-20-2006, 10:46 PM

I just over hauled two of mine and they are not that difficult.

Clamp the pump in a large vice with the shaft pointing down. Put a large C clamp from the end of the drive shaft to the back cover. Be sure to leave the pully nut in place and just even with the end of the shaft to prevent thread damage.

Screw it in until the back moves in enough to get a screw driver behind the spring clip that holds the back in place. Pop out the spring clip. Remove the clamp. Make sure that the back come up evenly. Check the distance between the back of the pump and the top edge of the back to make sure it is even all the way around. Turn the pump over and rap it hard on the work bench. The back should fall out. There is only a single thin O-ring holding the back in place. Once the back is off the pump rotor should just fall out. Be careful. There are about 6 or 7 blades in the rotor that will also fall out. Try to keep them in the same slots.

As I remember you can drive the shaft and bearings out the back by hitting on the pully end of the shaft. The seal can then be removed out the front. Mercedes offers a seal and O-ring kit for these pumps but be sure to get the pump model no. before you go to the MB shop. The bearings are available at any big bearing supply company.

When going back together be careful with the back cover and the O-ring. Use some lubrication and be careful not to cut the O-ring. I tested mine by getting an old power steering hose from a junker and connecting it to the out put side of the pump and hanging the other end back in to the reservoir. Install the pulley and spin the pump using an impact wrench on the pulley retaining nut. I also connected a guage to the out put hose and checked the pressure. Mine ran about 1,000 psi at the speed of the impact.

These pumps dont really wear out but the seals do leak. There is a relief valve internally on the side of the pump. No need to mess with it since there is really no way to adjust it, and no need to try.

Off the car, repaired and back on should take 4 hrs. if you have all the parts ready. It is not a very complicated job.

MonsieurBon · #10 05-20-2006, 11:55 PM

I just replaced the front seal on my ZF p/s pump. Remember to remove the key from the keyway! We were working too fast (friend's wife and kids hanging around) that my buddy started tapping the shaft through with the key still in place. It damaged the shaftway, and then we LOST the key when he was prying it out. We replaced it with a similar piece of metal, and the front seal went in just fine and hasn't leaked since.