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Installing Power Steering Filter

6K views 7 replies 4 participants last post by  43sqd 
#1 ·
I am replacing my power steering pump and at the same time, plan to install a power steering filter in my 2008 ML550 (which I have owned since new, and love). I would appreciate some advice on what line to place it in. The one I first thought to use is the line from the radiator to the bottom of the power steering reservoir (I assume flow is from the rad to the reservoir). I'll add the filter after flushing the old fluid.

Secondly, I would also like some advice on flushing the old fluid. This is what I am thinking. After the new pump has been installed, plug the small inlet at the bottom of the reservoir, and fill the reservoir with fluid. Then take the 3/8" line that normally goes from the rad to the PS reservoir, extend it to below the vehicle, and place it in a bucket. Then run the vehicle for a couple of seconds, add more fluid, and repeat until the fluid entering the bucket is clear. How does this sound?

Thirdly, is there a better type of o-ring to use at the connection from the pump into the reservoir? From what I have been reading, this connection is a problem.

Many thanks for any advice.
 
#2 ·
My understanding of any bleeding/replacing of the power steering fluid is to do it without starting the engine! The fluid will erupt out of the hose far quicker than practical.
I have read that disconnecting the return line and plugging its port will work. Keep the reservoir full and turn the wheel lock to lock (engine off). The old fluid will flow from the return line.

Curious as to your decision to install a filter.

Skippy
 
#3 ·
Lock to lock with the engine off. OK. I should then qualify for middle linebacker with any NFL team.

The filter was a recommendation from another mechanic and from where I bought the new power steering pump.

Any thoughts on the other questions?

Thanks.
 
#5 ·
The initial problem was with the rack leaking and I think the pump may have run dry for a brief period. The pump now makes a loud whining noise when I start the car, especially when cold, even with the fluid at the correct level. Steering is very stiff when the car is fully warmed up and I am at low speed; i.e., parking.

Anyway, I have the new pump and am ready to put it back on.
 
#6 ·
The last rack and pinion system/pump I flushed was a Volvo. I sucked the old fluid from the reservoir, then disconnected the return line and put it in a 2 liter soda bottle. Fill the reservoir with clean fluid and slowly turn the wheel rack to rack several times with the engine off. On the ML I would jack up both front wheels to take the weight off just so it's easier to turn the wheel. If you connect a clear tube to the return line into the 2 liter bottle, you can see when the old brownish fluid is out and new fluid is in. I have a second person monitor the reservoir and make sure it doesn't go empty.

Pay attention, don't start the car just unlock the wheel to turn it, if you start it the pump pressure will spray the ceiling with PS fluid. DAMHIK!

For a filter you could put it on either the in or out of the reservoir, both of those should be low pressure lines. I assume the filter has a magnet, make sure you pay attention to the flow arrow on the filter and install it correctly.
 
#7 ·
Thanks N41EF (sounds like a tail number?? - I fly too, a RotorWay JetExec helicopter) and others here for the advice. I will do as suggested and report back. That was a great and painfully-obvious-after-the-fact suggestion to jack up the front wheels. That will save the arms for other activities.

The outlet from the reservoir goes directly into the pump, so I'll put the filter in the inlet line to the reservoir.
 
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