How to remove the power steering pump on a w140 1995 S420

[slsproducts]

How to remove the power steering pump from a w140 1995 S420.

Since it took me 13 hours to do this, I figured I would write up what I did right to save everyone else hours of frustration. There are no pictures since I was too busy MF'ing the unknown German guy who had the bright idea to install this thing this way, so I apologize.

Remove the fan shroud so you have access to the 15mm nut on the tension pulley.

Crack the 3 - 13mm bolts loose from the PS pulley. Gently turn the tension pulley counter clockwise to loosen the belt and remove it from the tensioner and PS pulley.

Remove the PS pulley.

Remove the distributor cap case cover (2 plastic tabs/hooks. The cover goes over them).

Remove the coil wire (center).

Remove the wire connected to the CPS? (going through the metal bracket)

Remove the metal bracket holding the reservoir to the head (2 - 6mm allens and 2 - 10mm hex heads)

Remove the distributor cap by loosening the 3 - 5mm? allens. They will not fall out of the cap.

Carefully move the cap and wires to the intake manifold (out of the way)

Remove the distributor cap case. 3 - 5mm allens. You will probably need an allen wrench unless you have a 3-4 inch allen socket for the one hidden on the bottom under the distributor cap location. You will have to pull forward and turn the case counter clockwise to get the thin part inbetween the PS reservoir so you can remove it.

You will have access to the high pressure hose but if you remove it now, you will have a mess under your car. You don't want it dripping on you so hold off on removing it.

Now the fun stuff... There are 3 bolts holding the PS bracket to the motor. There is 1 - 6mm allen on the front side and 2 - 13mm hex heads on the back side.

Pictures of the removed pump and bracket can be found here. 400E Power Steering Pump

Just below and to the left of the reservoir, you will find the allen head bolt. It is hard to see. Remove it.

If you have a thin ratchet, use it. If you are like me and you do not, use a 13mm socket and a regular ratchet and break the bolt on the right side loose (where the guy's middle finger is pointing to in the picture in the thread above). Your ratchet will probably hit the exhuast manifold. I had to use a pivot joint to remove the bolt. Since the pivot was at almost a right angle, it would jam every 1/2 turn.

Now for the bolt you can't see. I used a 13mm socket - 3/8" pivot joint - and 17 inches of extensions to get to and remove this bolt. I placed my work light top side and illuminated the back side of the PS bracket. I was able to get a "line of sight" to the area, where the bolt was supposed to be, from the driver's side of the oil pan.

I manuevered the socket contraption up into the area from the side of the oil pan. I was able to see the socket, and almost the bolt, when I moved just in front of the cross member. I took a wild guess at the socket being on the bolt head firmly. I then attached my ratchet and broke the bolt loose.

After loosening the bolt all the way, I left the socket and extensions attached to the bolt. I left the bolt in the mounting hole. If I would have removed it, I would have had a hell of a time getting it back in.

While you are under there, loosen up the PS return line hose clamp. When you seperate it, you will have some fluid come out.

Go top side and loosen the high pressure hose. (17mm or 11/16)

Pull the assembly forward and up. You will have to remove a ground wire (10mm) from the rear of the bracket before you can pull it all the way out.

When you are reinstalling your bracket, attach the allen bolt in the front and the hex head on the right rear. Do not tighten them up until you get the impossible to see hex head in and tight. Don't forget the ground wire.

I hope this saves someone a whole hell of a lot of time. Thank you emerydc8 for the pictures of the bracket. I would not have found the bolt without your pics. As far as I can tell, they are the only ones on the internet.

[whunter]

Added to Steering:

[Andras]

Thanks for pointing out where the mounting bolts were hiding. I spent several evenings removing the pump.

[emerydc8]

I didn't know it at the time (six years ago), but there was a much easier way to reseal my power steering pump. The front of the pump will come off just by removing the six 13mm bolts on the front. That way, you can access the pump radial seal (the most likely to leak) without taking the whole pump or bracket off.

If you have a tandem pump (self leveling system), you have to take the whole pump off to seal it, but you can still take the whole pump off without removing the bracket by removing the two Allen bolts on the back of the bracket and two 13mm bolts on the front. Here is an excellent writeup by Gerry VZ on removing the tandem pump, which applies equally to the non-tandem pump on the 400E/E420.

Power Steering Pump Leak Investigation

If you really need to remove the bracket, it makes it much easier to get to that 13mm bolt on the back if you take the front exhaust manifold elbow off. I think it is held on with 10mm bolts and they can be accessed from the top of the engine compartment. Although you can't see the manifold bolts from there, you can feel for them and remove with a 1/4" drive ratchet. I reused the paper thin metal gasket that goes on the manifold elbow and had no problem with exhaust leaks.

[benz.rebuilder]

Thanks for the information... I am trying to order a seal kit for the leaking ps pump on my 1995 S420... How do I know which pump I have and which kit to order... The only number I can find on the pump is 768 501 121... Thanks in advance for helping out

[emerydc8]

That is the ZF part number. Get some brake parts cleaner and clean the tag up so you can see the Mercedes part number below it. Look at the tag in the picture. Do you have self-leveling on your car?

[SCLASS600]

HOW TO DO YOU REMOVE THE RESEVIOR FROM THE PUMP WITH OUT DAMAGE