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Power Steering Flush - Mercedes Benz
 
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Pelican Technical Article:

Power Steering Flush - Mercedes Benz

Steve Vernon

Time:

1 hour1 hr

Tab:

$26

Talent:

*

Tools:

Turkey baster or some form of sucking device, 10mm wrench

Applicable Models:

Mercedes-Benz W124 (1986-95)
Mercedes-Benz W201 (1984-93)

Parts Required:

Power steering filter and fluid

Hot Tip:

Don't open the lines

Performance Gain:

Sharper steering input

Complementary Modification:

Check your steering linkage

There are several thoughts and methods on changing the power steering fluid in a W201. Some people claim that it is a lifetime filter and fluid, to which other people ask, "Then why do they make replacement filters and fluid?" I am not a big believer in lifetime fluids and if there is a changeable filter, I am going to change the fluid as well.

If you are going to change the fluid there are two schools of thought on doing it. The first school of thought is to completely flush out the system while simultaneously adding new fluid. This involves opening the return line to the reservoir and placing a large bucket for the fluid to empty into under it while being prepared to add several liters of clean fluid into the reservoir. Have someone start the car and turn the wheel while you are pouring new fluid into the reservoir so it doesn't run dry. I do not recommend this method for a lot of reasons. First: You will use a lot of fluid. You will be shocked at how much of a volume your pump can move, and the fluid is not cheap. Second: It can get extremely messy, as everything is slippery and moving under pressure. Third: If you let your pump run dry, even for a few seconds, you can severally damage it.

I prefer the "old school" method of sucking as much fluid as you can out of the reservoir, replacing the filter and adding new fluid. The fluid will not stay perfectly clean as there is still a fair amount of fluid in the lines and pump, but if you do repeat sucking out the fluid and replacing every couple of weeks eventually you will end up with very clean fluid at a much cheaper cost. Also, the fluid has been in there for years, it can wait a few more weeks until it is all changed out.

Working on a cool-to-touch car, unscrew the cap of the power steering reservoir, it is located by the belt tensioner.

Use a turkey baster or suction pump to remove as much fluid as you can. Push the plastic stalk in the middle of the filter down and undo the 10mm nut. Remove the plastic stalk, spring and the metal filter underneath. Suck as much fluid as you can out of the reservoir, getting it as clean as possible. Install the new filter and replace the spring, plastic stalk and the 10mm nut. Fill the reservoir to the appropriate level. Change the seal on the cap and replace the cap. You can now start the car and turn the wheel side to side to get the new fluid circulating, then suck out more and refill. You can repeat this process until the fluid remains clear.

Locate the power steering reservoir by the belt tensioner (yellow arrow).
Figure 1

Locate the power steering reservoir by the belt tensioner (yellow arrow). Undo the cap, (it just unscrews) and set aside.

Use a turkey baster or fluid pump to remove the fluid in the reservoir.
Figure 2

Use a turkey baster or fluid pump to remove the fluid in the reservoir. Undo the 10mm nut and remove the plastic stalk and spring

Remove the old filter.
Figure 3

Remove the old filter.

Remove as much fluid as possible and clean the inside of the reservoir.
Figure 4

Remove as much fluid as possible and clean the inside of the reservoir.

Install the new filter, reset the spring, stalk and the 10mm nut.
Figure 5

Install the new filter, reset the spring, stalk and the 10mm nut.

Fill with new fluid.
Figure 6

Fill with new fluid until an inch from the top, then bleed the system until there are no bubbles left in the reservoir. 

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Comments and Suggestions:
taz Comments: I have added a lubrication oil which was recommended by Mercedes Benz for my automatic gearbox .my question is is it a right thing I did or I might damage something else
August 7, 2016
  Followup from the Pelican Staff: You didn't mention what vehicle you have. BUT if Mercedes recommended it, I can't see how they would be wrong. - Nick at Pelican Parts  
DanaR Comments: Wondering how to check the lwvel on my power steering pump? 1990 190e.
I noticed a small slow leak that is very possibly coming from the power steering.
Also not sure if it is related or not but about the time I noticed the leak my belt groans upon starting and only does so for about 30 seconds unless I turn the wheel...then it will continue to groan for a couple minutes.
Thanks!!
May 6, 2016
  Followup from the Pelican Staff: Fill it until it is about an inch from the top. Bleed system until not bubbles are left in reservoir. - Nick at Pelican Parts  
Merctech36 Comments: What type of power steering fluid does my car take
December 27, 2015
  Followup from the Pelican Staff: What is the year and model of the vehicle?
- Nick at Pelican Parts
 
Jacques405 Comments: Thanks a lot for this very good technical article.
I am in the middle of doing the PS flush old school style using dextron 3 auto trans fluid on my '93 190E 1,8L.
Then i discover there is a bit of a debate, some people say use auto gear box oil in the power steering, some people say use only the special fluid. What do you reckon?

Another question : My next job is the oil gear box change. What is the size of the Allen tool i will need for the drain and filling plugs?
Thanks in advance.
November 10, 2015
  Followup from the Pelican Staff: I would use the power steering hydraulic fluid the vehicle was originally equipped with. - Nick at Pelican Parts  
magician Comments: you guys are the best internet site for this car. thank you again very much gentlemen.
September 12, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
JIM Comments: Sandy,

First of all I calculate 83% check your numbers.
I have read the turkey baster method and actually running your engine both of which are kind of ludicrous and sloppy.

Why not put a pan under your return hose extend the hose if you want. Then fill the reservoir with power steering fluid and turn the pulley by hand until you get the new fluid, filling the reservoir as necessary. Then you have flushed the power steering system.
September 11, 2014
  Followup from the Pelican Staff: Thanks for adding to Sandy's comments. - Nick at Pelican Parts  
Sandy Comments: Another good guide. Thanks guys. I bought 2 litres of fluid and extracted 300mls at each partial flush so by my calculations 6 consecutive flushes with some driving in between to remix the old and new fluid means almost 90% of the steering fluid has been renewed and I have 200mls left over for future tops ups if needed.
September 7, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
rickyb Comments: thank you for all your help
July 15, 2014
  Followup from the Pelican Staff: No problem. - Nick at Pelican Parts  
shovel Comments: fantastic
November 28, 2013
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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