power steering flush - PeachParts Mercedes-Benz Forum

crashone · #1 05-05-2007, 01:30 AM

I just did this 2 weeks ago and the fluid is pretty dark already. My question is what other fluid (like hydrualic fluid) can be used to flush these systems out? I pumped 4qts through when I did this and the fluid never got 100% clear. I want to buy something in bulk that won't cost a lot of money (ie: 4qts power steering fluid = ~$20.00) and was wondering if reg hydraulic fluid would work or will I be asking for trouble? Thanks.

#2 05-05-2007, 01:38 AM

ATF and P/S fluid are all that should ever go through it.

To clear out all the old fluid from the system: Suck out all the fluid from the reservoir (Turkey baster, MityVac, etc), remove the return line, drain the return line by getting it as low as possible (Lower than the gearbox, no part of the line can be higher), lift the front wheels off the ground, turn the wheels lock-lock at least 3 times (engine off), and reconnect the return line. That will get out as much of the old fluid as possible.

crashone · #3 05-05-2007, 01:48 AM

Thanks I changed it last year and used ATF but wanted to clean it up again. I hadn't thought of raising the front

(duh) but I did turn the wheel etc. I'll have to try that.

aklim · #4 05-05-2007, 09:05 AM

Quote:

Originally Posted by ForcedInduction

ATF and P/S fluid are all that should ever go through it.

To clear out all the old fluid from the system: Suck out all the fluid from the reservoir (Turkey baster, MityVac, etc), remove the return line, drain the return line by getting it as low as possible (Lower than the gearbox, no part of the line can be higher), lift the front wheels off the ground, turn the wheels lock-lock at least 3 times (engine off), and reconnect the return line. That will get out as much of the old fluid as possible.

Would that work for my car too? 99 E300

Mister Byrnzoil · #5 05-05-2007, 10:25 AM

my fluid was black when I got my car, I removed the (OE?) ps filter. pumped out the old fluid (thru the return line) put in new fluid and drove around for a couple of days, then repeat process and install new filter, fluid is still reasonably clear after almost a year.

Matt L · #6 05-05-2007, 10:38 AM

Quote:

Originally Posted by aklim

Would that work for my car too? 99 E300

It will probably dump a bunch out, but you won't get it all.

Be sure to completely purge your rack of air before you drive the car on the highway, or you won't like it one bit. Any air in the rack makes the damping action completely ineffective.

oldnavy · #7 05-05-2007, 11:56 AM

The whole system only holds about 2 liters of fluid, the way to do this fluid replacement is quite simple but requires a second person.

You need a 2L soda bottle, 2 or 3 liters of PS fluid, not auto tranny fluid. I believe it was 95 or 96 before they started using auto tranny fluid, but owners manual should say. My 91 W124 300D OM states PS fluid only, not tranny fluid.

1. suck the fluid out of the PS reservior with turkey baster and remove the filter.

2. Once the fluid and filter are removed, disconnect the upper PS hose on the reservior (return line) and insert it in the top of the 2L soda bottle.

3. fill the reservior up to where the return line was and have someone start the car and as they turn the steering wheel back and forth you need to be pouring fluid into the resevior so it does not suck dry. I would have both bottles of the PS fluid open and ready to go. It will only take about 30 seconds this way to clear all the fluid from the rack and the lines.

I went to the local hardware store and got a plug made up so I could seal the return line hole and that way have more fluid in the resevior, but it is not really needed.

When I changed the muddy crap out of my 300D last month I had a friend help me and it only took about 15 minutes from start to finish and I didn't spill any fluid. I also installed a new filter as the one I removed looked like it may have been the original. Like I said when the fluid is changed this way it is fast and all the old fluid is removed and will not contaminate the new fluid and it is as I said about 30 seconds of fluid flow before all the old is gone and you have completely replaced all the old fluid with new fluid.

crashone · #8 05-05-2007, 01:06 PM

Thats what I did last year only I used ATF as the manual said to use. This year I used power steering fluid and got it to be very lightly tinted. When I checked it out last night I was surprised to find it so dark/ dirty after flushing out with all the power steering fluid. That's what got me thinking about using the hydraulic fluid. Whats the difference between the 2 anyway? Thanks.

oldnavy · #9 05-05-2007, 03:25 PM

Quote:

Originally Posted by crashone

Thats what I did last year only I used ATF as the manual said to use. This year I used power steering fluid and got it to be very lightly tinted. When I checked it out last night I was surprised to find it so dark/ dirty after flushing out with all the power steering fluid. That's what got me thinking about using the hydraulic fluid. Whats the difference between the 2 anyway? Thanks.

It just depends on how the pump is made. D/C has come around to using ATF for the PS in their cars as has MB, not shure who made the switch first. That said our '87 Jeep Cherokee used ATF for the PS, and 91 MB says use PS fluid as did my 83 W123 240D. I think the change for MB was mid 90's sometime, but your OM should say witch to use. Mine says PS fluid and thats what I use.

Mister Byrnzoil · #10 05-05-2007, 03:26 PM

did you change the filter?

power steering fluid is hydraulic fluid, its thinner than most that I have used in heavy equipment, but it has the same corrosion inhibitors and anti-shear properties, and possibly detergent additives.

oldnavy · #11 05-05-2007, 04:16 PM

Main difference is the viscosity and additive package. The current tranny fluid will cause the older MB PS to leak at all the seals. When I bought my 83 MB it had major PS leak(s), it was cured by switching to PS fluid, same brand as I used last month in the 300D.

pawoSD · #12 05-05-2007, 04:17 PM

Generic synthetic P/S fluid is only like $1.89 /qt at Autozone. I just bought 5 bottles of that, and 2 bottles of the good stuff. (Valvoline ProSynth P/S fluid) Flushed with the cheap stuff, filled with the good stuff.

crashone · #13 05-05-2007, 09:07 PM

Yes I changed filters last year and this time (~15-18000 miles). I guess I'll go hit the wally world for some cheap PS fluid along with some good stuff and pick up another filter and go at it again!!

oldnavy · #14 05-05-2007, 11:18 PM

Quote:

Originally Posted by crashone

Yes I changed filters last year and this time (~15-18000 miles). I guess I'll go hit the wally world for some cheap PS fluid along with some good stuff and pick up another filter and go at it again!!

Don't forget a cheap 2L bottle of Wal-Mart soda, at $0.59 you can afford to pour out the soda and use the bottle as a catch jug since it will fit done in the engine compartment and the hose fitting will fit in the bottle and not blow out catching all the fluid. Do the way I posted above and 2 or 2.5 liters is all you need to have the fluid flushed.

Have fun.