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Pelican Technical Article:

Power Steering Pump Removal

Kerry Jonsson

Time:

4 hours4 hrs

Tab:

$410

Talent:

***

Tools:

5mm, 6mm Allen head, 10mm, 13mm socket with ratchet and extensions, 17mm wrench, Phillips head screwdriver

Applicable Models:

Mercedes-Benz R129 (1990-02)

Parts Required:

Power steering pump, aluminum washers, power steering fluid and filter

Hot Tip:

Use a suction tool to draw fluid out of the reservoir before removing

Performance Gain:

Power steering assistance, quiet noisy pump

One of the major accessories that run off of the accessory drive belt is the power steering pump. The power steering pump is unique on your vehicle because of all the components in the car the power steering pump produces the most pressure of any system. It is not unusual for a power steering pump to produce 2000 to 3000psi while under load from the vehicle turning. On certain Mercedes Benz models this pump also provides hydraulic pressure for suspension and braking systems as well. In the case of our 1990 -1998 Mercedes Benz 500SL, SL500 it is used for power steering. The power steering pump has the reservoir built into the pump and has a replaceable filter in it. In this tech article we will go over all the necessary steps to replace your power steering pump.

In order to replace your power steering pump you are going to need to remove the accessory drive belt. See our tech article on replacing the accessory drive belt for further instruction on removal. You do not have to take off the cooling fan and shroud to perform this task but it does give you more room to work. We have removed these parts for photographic purposes.

ThisPicture illustrates the left side of the engine.
Figure 1

ThisPicture illustrates the left side of the engine. Remove the three 13 mm fasteners (green arrows) that mount the power steering pulley to the pump flange. The pulley will spin freely while trying to remove the fasteners. You can use a screwdriver to hold the pulley still by placing it between two mounting bolts while you loosen the third as illustrated here. You can also use a strap wrench and wrap it around the pulley to hold it still.

Remove the pulley from the power steering pump.
Figure 2

Remove the pulley from the power steering pump.

Use a 17 mm wrench or line wrench and loosen the power steering pressure feed hose.
Figure 3

Use a 17 mm wrench or line wrench and loosen the power steering pressure feed hose.

This photo illustrates the front of the power steering pump and reservoir housing.
Figure 4

This photo illustrates the front of the power steering pump and reservoir housing. To remove the power steering pump you need to separate the entire housing assembly from the block. You can start by removing the four 13 mm fasteners (green arrows) that secure the front of the power steering pump and the hose clamp (yellow arrow)

Lift the hose up to unseat it from the power steering pump.
Figure 5

Lift the hose up to unseat it from the power steering pump.

To remove the entire housing remove the three 13 mm mounting fasteners (green arrows) and one 5mm Allen head fastener recessed in the bracket (yellow arrow).
Figure 6

To remove the entire housing remove the three 13 mm mounting fasteners (green arrows) and one 5mm Allen head fastener recessed in the bracket (yellow arrow). The housing can now be rotated downward away from the block.

Remove the tie down (green arrow) that holds some electrical wires to a bracket on the power steering pump housing.
Figure 7

Remove the tie down (green arrow) that holds some electrical wires to a bracket on the power steering pump housing.

With a Phillips head screwdriver remove the reservoir return pipe hose clamp and remove the hose from the line.
Figure 8

With a Phillips head screwdriver remove the reservoir return pipe hose clamp and remove the hose from the line.

Position the power steering pump so you are looking at the back of it.
Figure 9

Position the power steering pump so you are looking at the back of it. Remove the 10 mm fastener that holds on the ground strap (green arrow). Also remove the two 6 mm Allen head fasteners (yellow arrows) that hold the back of the power steering to the housing. You should now be able to remove the power steering pump from the housing. Installation is the reverse of the removal steps. Position the power steering pump in the housing and tighten the two Allen head fasteners that attach from the rear. Attach the 10 mm bolt that holds down the ground strap. Attach and tighten the hose and clamp for the reservoir return line. Position the housing off against the block and tighten the four fasteners that hold it on. Remember one is a 6 mm Allen head fastener recessed in a hole under the power steering reservoir. Install and tighten the four bolts that hold the front of the power steering pump to the housing. Fit the pulley and install the three mounting fasteners. Install and tighten the accessory drive belt and any other components you removed to finish this job. Make sure the power steering reservoir is full of the proper power steering fluid before starting the engine. You will need to turn the steering wheel from lock to lock to bleed the air out of the system and let the car sit while the air bubbles come out of suspension of the power steering fluid. Repeat this until the power steering pump is quiet when turning the wheel.

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Comments and Suggestions:
Xe Comments: The explosion diagram doesn't show the reservoir that is on my 1996 SL 500. Is there a gasket between the reservoir and the unit?
July 7, 2016
  Followup from the Pelican Staff: Yes, I believe so.

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Darren Comments: There is a bolt on the back of the bracket that is barely visible from the underside. It is sandwiched between the AC line and the PS return hose. 13mm head. Good luck is all I can say.
January 26, 2016
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it. - Nick at Pelican Parts  
Phil Comments: I'm following the Power Steering Pump Removal procedure in your Technical Articles section for the 90-92 Mercedes 500SL.
After taking all the bolts out and checking the procedure numerous times to see if I left anything out, I can't seem to get the pump and bracket to budge. I took the 3 bolts and 1 hex bolt pictured in Figure 6 out. I also had the 4 bolts out in Figure 4 still couldn't budge the bracket but put them back because that opened up the pump and didn't seem to be long enough to be bolted to the block. I don't want to break anything by using a pry bar so I just wanted to ask if there were any other fasteners that you may have missed in the article. I can't find any. Or do I just have to break that thing loose with a pry bar. I'm frustrated
Anyway, I hope you can shed some light because I'm dead in the water.
Some BenzWorld Forum people are saying that there is a E12 fastener that can only be gotten from underneath but they had newer cars with a different bracket. I'm uploading a picture of the bracket on the 90-92.

By the way, I could be wrong but, in Figure 4, you have the bottom green arrow pointing to the bracket bolt and not one of the 4 pump housing bolts.
Also, in figure 6, my car had a 5.5mm Allen head fastener.

Any help would be greatly appreciated.

Thanks
Phil
pdesimone@comcast.net
732-864-5299
June 6, 2015
  Followup from the Pelican Staff: See attached exploded diagram. I think there is a bolt in the back you may have missed. - Nick at Pelican Parts

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