1993 W124 300D Draining/Replacing Power Steering Fluid - PeachParts Mercedes-Benz Forum

i-osprey · #1 09-04-2009, 12:16 AM

What exactly is the procedure for draining the old power steering fluid?

I have a replacement filter that I will install after I have ran it for a while with the new fluid and old filter.

I also have quart of MB PS fluid, not synthetic.

Is this enough fluid to do a complete refill?

Olivier · #2 09-04-2009, 06:00 AM

There was a DIY around that I followed. It was like this:
Pump the fluids out of the resevoir, fill it up with new fluid.
Start the car, lock the wheels on both sides.
Stop the car.
Empty the reservoir again. Fill it up with new fluid.
Start the car, lock the wheels on both side
and repeat the procedure untill the fluid left in the resevoir is clean/ new

#3 09-04-2009, 07:51 AM

I'm sorry, but Oliviers method will require a TON of fluid and will never really get the system clean.

I call the following method the ASE method because it is the method around which questions on the ASE test are asked. You will need five fresh quarts of power steering fluid, a drain pan, a way to suck out the old fluid from the reservoir and enough tools to disconnect and replace the power steering return line from the reservoir. The steps are as follows:

o Remove the reservoir cap and suck the fluid out of the reservoir.
o Disconnect the return line from the reservoir and lower it into a drain pan below.
o Open three quarts of fluid and have them ready to pour in and fill the reservoir.
o Instruct an assistant that when they start the engine they should start turning the wheel back and forth lock to lock while watching for the signal to kill the engine.
o Once the engine is started, begin with the fresh fluid and keep the reservoir from going empty until all three quarts have been poured through and the reservoir is empty. At that point signal the assistant to kill the engine.
o Reconnect the return line and fill the reservoir, then signal the assistant to restart the engine and start turning lock to lock again while you fill the system until it will take no more fluid.
o Replace the reservoir cap and dispose of the fluid in the drain pan.

DO NOT USE ANY SOLVENTS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! USE ONLY CLEAN P/S FLUID FOR THE FLUSHING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

And that's all there is to it. It doesn't take very long at all to do this and as a result you will have a completely clean P/S system. If you are doing this on an MB, it would be a great time to change the filter at the bottom of the reservoir. Many other brand cars don't have a filter though.

Good luck,

sixto · #4 09-04-2009, 11:27 AM

Either Larry is an optimist or I need a bigger pulley on my PS pump. My system will flow a gallon of PS fluid in a matter of seconds. I barely keep up fill the reservoir.

I started on a system with ATF and even after a number of flushes pale yellow Febi fluid still turns pink. I flush first with bulk PS fluid (clear) then finish with 2 quarts of what I want to leave in there.

Larry, will there be a thorough flush using cranking speed rather than idle speed?

Sixto
87 300D

Jeremy5848 · #5 09-04-2009, 11:37 AM

I agree with Sixto. I found that the PS pump moved the fluid so fast that I could not keep up and ended up pulling air into the system. I went through most of a gallon of fluid before I got the system purged and full of clean fluid.

I suggest one of three alternatives:
(1) use Sixto's idea of cranking the engine while making sure the STOP lever is firmly pressed down so the engine can't fire.
(2) loosen the appropriate belt and spin the PS pump pulley by hand
(3) use a clamp on the return line so the escaping fluid is reduced to an amount that you can keep up with.

Options (1) and (2) and maybe (3) will require jacking up the front of the car so the front wheels are off the ground. Turning the wheels from side to side will thus be much easier.

Jeremy

Olivier · #6 09-04-2009, 02:15 PM

the trick is not letting the engine running. It did worked, no need for tons of fluids. The pump top up the top of the reservoir, this is why you keep on taking the top fluid.
Olivier
Got the DIY, here we go guys

http://www.benzworld.org/forums/w210-e-class/1413826-photo-diy-power-steering-fluid-change.html

i-osprey · #7 09-05-2009, 01:08 AM

Thanks for all the replies.

I have a new filter and gasket and will do the above recommended procedure since I won't have a helper and it sounds like it would have been dicy anyway.

I will get some cheap, bulk power steering fluid, suck out the reservoir, refill, run for a while driving and turning wheel lock to lock, repeat.

I'll post my results.

My fluid is very dark and cloudy so I suspect it is well over due.

Cr from Texas · #8 09-05-2009, 01:51 AM

Quote:

Originally Posted by Jeremy5848

I agree with Sixto. I found that the PS pump moved the fluid so fast that I could not keep up and ended up pulling air into the system. I went through most of a gallon of fluid before I got the system purged and full of clean fluid.

I suggest one of three alternatives:
(1) use Sixto's idea of cranking the engine while making sure the STOP lever is firmly pressed down so the engine can't fire.
(2) loosen the appropriate belt and spin the PS pump pulley by hand
(3) use a clamp on the return line so the escaping fluid is reduced to an amount that you can keep up with.

Options (1) and (2) and maybe (3) will require jacking up the front of the car so the front wheels are off the ground. Turning the wheels from side to side will thus be much easier.

Jeremy

Does method (3) create a potential of damaging any components by restricting the flow? Seems to me that would increase the internal pressure of the system. Was that a tested method or just an "off the top of the head" response? If it's a good method, one could easily clamp in a ball valve at the end of the disconnected return line.

Olivier · #9 09-05-2009, 04:39 AM

Quote:

Originally Posted by i-osprey

Thanks for all the replies.

I have a new filter and gasket and will do the above recommended procedure since I won't have a helper and it sounds like it would have been dicy anyway.

I will get some cheap, bulk power steering fluid, suck out the reservoir, refill, run for a while driving and turning wheel lock to lock, repeat.

I'll post my results.

My fluid is very dark and cloudy so I suspect it is well over due.

You don't drive the car

, the car stay stationary. What you do is just empty and replaced the old fluids that come back on top of the reservoir from the pump after locking the wheels both side.

#10 09-05-2009, 08:32 AM

Do you guys really think that I have never personally used this method before?

I have used this method dozens of times. Yes, the fluid goes through rapidly, but three quarts will flush the system adequately.

If you prefer taking longer to do the process, simply don't turn the steering wheel lock to lock.

Do you guys think that the ASE would prefer this method if it were not effective?

drgreenthumb · #11 09-05-2009, 09:16 AM

Quote:

Originally Posted by LarryBible

I'm sorry, but Oliviers method will require a TON of fluid and will never really get the system clean.

I call the following method the ASE method because it is the method around which questions on the ASE test are asked. You will need five fresh quarts of power steering fluid, a drain pan, a way to suck out the old fluid from the reservoir and enough tools to disconnect and replace the power steering return line from the reservoir. The steps are as follows:

o Remove the reservoir cap and suck the fluid out of the reservoir.
o Disconnect the return line from the reservoir and lower it into a drain pan below.
o Open three quarts of fluid and have them ready to pour in and fill the reservoir.
o Instruct an assistant that when they start the engine they should start turning the wheel back and forth lock to lock while watching for the signal to kill the engine.
o Once the engine is started, begin with the fresh fluid and keep the reservoir from going empty until all three quarts have been poured through and the reservoir is empty. At that point signal the assistant to kill the engine.
o Reconnect the return line and fill the reservoir, then signal the assistant to restart the engine and start turning lock to lock again while you fill the system until it will take no more fluid.
o Replace the reservoir cap and dispose of the fluid in the drain pan.

DO NOT USE ANY SOLVENTS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! USE ONLY CLEAN P/S FLUID FOR THE FLUSHING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

And that's all there is to it. It doesn't take very long at all to do this and as a result you will have a completely clean P/S system. If you are doing this on an MB, it would be a great time to change the filter at the bottom of the reservoir. Many other brand cars don't have a filter though.

Good luck,

This is what I did and it worked very well. The only variation was I didn't have an assistant so I engaged the engine stop so it would not fire. As I was cranking the engine I turned the steering wheel lock to lock. It was easy to keep up with filling the reservoir. I strongly recommend finding an assistant so you are not cranking the engine so much.

I did not start with cheaper fluid before I poured in the MB fluid. I am not sure what the alternative would be to just flush the system. I don't think the MB fluid can be mixed with other ps fluids. It is the same fluid Audi uses. The MB fluid is re-labeled Pentosin 11S BTW. The pentosin quart will cost half of what the MB quart will.

i-osprey · #12 09-05-2009, 06:53 PM

Well, the MB fluid I have is not synthetic and is yellow.

Also, I only have one quart of it.

I didn't know I needed two to refill.

Jeremy5848 · #13 09-05-2009, 09:53 PM

Quote:

Originally Posted by Cr from Texas

Does method (3) create a potential of damaging any components by restricting the flow? Seems to me that would increase the internal pressure of the system. Was that a tested method or just an "off the top of the head" response? If it's a good method, one could easily clamp in a ball valve at the end of the disconnected return line.

It's what I want to try this Fall when I next change PS fluid in the '87 and the '96. I wasn't planning to totally clamp off the hose, just cut the flow down to half or a third of what flows through a totally open hose. Yes, a valve could be used but I have adjustable hose clamps so will use what I have. I doubt that it would damage anything or I wouldn't have suggested it -- however, let's see if anyone else thinks it could cause problems. I won't be doing the flush until November so I have time to change my mind.

Jeremy

#14 09-06-2009, 10:17 AM

The regular Power Steering fluid from the auto supply works perfectly in a Benz.

There is no need to clamp off any hoses. Clamping hoses of any kind is NOT a good idea. It can easily damage a hose.