Best way to seriously flush PS system?

[dukeofchen]

I'm finally getting around to a full PS system refresh – reservoir, hoses / lines, pump. My old pump has been on it's way out for a while, to the point where it's puking glitter into the fluid.

My main concern with the new parts going in is getting all those particulates out of the rack and the cooling circuit to protect the new pump, so wondering if anyone has thoughts on best methods to do so.

My thought process so far is:

• Disconnect the return line and plug the reservoir inlet it connects to, using the return line as the draining point
• YOLO it using the old pump and the engine to push fluid through the system at as high a flow rate as possible. Since the pump is getting replaced anyways less concerned about the system running dry.
• Replace the parts starting from the reservoir down, possibly in stages and continuing to flush clean fluid through the system
• Installing an inline magnetic filter for good measure, at least for a short period as insurance

[Slideways]

The reservoir has a filter in it. It would have caught a majority of the larger metal. After running the new pump for a few minutes, flush the system one or two more times. Basically, the second option

[bmwfnatic]

I’ve done the return line removal method and stick it in a large soda bottle, but you almost need a second person to look as the other starts the car, it goes really fast.

The drain and fill and repeat a few times method is probably also sufficient.

[bigjae46]

I'd disconnect the suction and discharge lines on the pump and blow out the lines/turn the steering wheel.

For regular maintenance, I use a vacuum bleeder to empty the reservoir and fill up with fresh fluid with every oil change.

[dukeofchen]

The reservoir has a filter in it. It would have caught a majority of the larger metal. After running the new pump for a few minutes, flush the system one or two more times. Basically, the second option

Yeah I replaced the reservoir not too long ago, so I imagine the fresh one caught more of the particulates. But the fluid that came out that time was pretty concerning despite the reservoir filter, tons and tons of fine metal shavings that I could see under light. So last thing I want is friction material flowing through the new pump and wearing it out prematurely.

I’ve done the return line removal method and stick it in a large soda bottle, but you almost need a second person to look as the other starts the car, it goes really fast.

The drain and fill and repeat a few times method is probably also sufficient.

I see, yeah I figured it would be pretty violent if the engine actually turns over, so maybe to start I would pull the fuel pump fuse and engage the starter to push fluid out if I go this route.

[D-O]

When I replaced the pump on my E91 I had the same concerns.

I installed a new reservoir and pump. Leave the belt off for now. New suction line attached to new pump, return nipple plugged and the return hose was dropped in a drain bucket. Fill up the reservoir.

I waded up a piece of old inner tube on the end of a short socket extension and attached it to my electric ratchet. Push the wadded up inner tube against the power steering pulley and have the ratchet spin the pump. When the reservoir gets low stop and fill it up. Keep going until you get clean fluid out of the return line. You will need to have someone turn the wheel back and forth to really get all the old fluid out.

[heinzboehmer]

I see, yeah I figured it would be pretty violent if the engine actually turns over, so maybe to start I would pull the fuel pump fuse and engage the starter to push fluid out if I go this route.

The shaft of the pump has a hex drive in the middle. Take the belt off and spin it with a drill/impact/electric ratchet so it's not as crazy.

[bigjae46]

Yeah I replaced the reservoir not too long ago, so I imagine the fresh one caught more of the particulates. But the fluid that came out that time was pretty concerning despite the reservoir filter, tons and tons of fine metal shavings that I could see under light. So last thing I want is friction material flowing through the new pump and wearing it out prematurely.

It is a coarse screen filter so it won't stop glittery metal stuff from flowing through.