Thoroughly flushing a power steering circuit

[rcx132]

There was a leak on my steering rack. It's a £300 spare car so I just put in some leak-stop fluid. It didn't work and the leak was bad so I'm replacing the steering rack.

Some of the fluid with the leak-top additive spilled onto the tyre. The tyre swelled up. So that's how the stuff works, it swells the rubber seals (and has wrecked my tyre). I really want that c**p out the system before I fit the new steering rack.

Just trying to figure out how best to flush it out. Found the circuit diagram below. So it looks that if the steering wheel is not being moved then the hydraulic fluid just circulates between the pump and the orbital valve and reservoir.

My steering rack is removed. So if I fill the system with cheapo oil and run the engine then the oil will just circulate. So I can change it several times.

If I then turn my steering wheel then it will divert oil down one of the hoses to the rack to flush that. Then turn the wheel the other way to flush the other hose.

Is this a sound plan?

 

[angellonewolf]

i dout just running a nd flushing will remove all the addative as its designed to stay put once added or it would be useless

 

[frank horton]

I'd undo every connection and blast out the old oil with an airline...a bit messy, thats if u can get to all the unions......
fit the rack and use new oil, run for five mins and do the same...
then I'd say it'll be clean enough.....long winded but life is not a race, well all the time....

 

[armalites]

With some cars the return to the reservoir is at the top so you can just disconnect and stick it in a container. If you suck out the reservoir so it's empty and fill with fresh it won't take much to flush it out. If it's an older car then it will probably take regular ATF which won't cost a fortune if you buy 5L. I normally flush out an new(to me) car I get because you can guarantee it will never have been changed.

 

[rcx132]

Thank you all !

 

[rcx132]

Interesting, this car has no orbital valve. There's just a pump connected to the steering rack with two hoses, with the return going via a reservoir.

 

[anto44]

The orbital valve is part of the steering rack.
Here's a rack with the input housing removed. Steering column attaches to the splined part I'm pointing at and you can see the valve below it.

 

[rcx132]

The orbital valve is part of the steering rack.
Here's a rack with the input housing removed. Steering column attaches to the splined part I'm pointing at and you can see the valve below it.
View attachment 145663

D'oh, of course! Ok great so all I need to flush is the pump and hoses as the rack is new. Makes life easier then. Thank you!

 

[rcx132]

So flushing the system will be easy as it's just the pump ツ

The new steering rack has arrived, it's the same, identical, except that the splined shaft that attaches to the steering wheel shaft is slightly different. Gutted now as need this car on the road for upcoming holiday.

Thinking that I should just fix the old rack. I've done specialist rebuilds like diffs, including setting backlash, pre-torque, mesh etc. So should be able to handle the rack, but how hard are they?

BTW the shop that supplied the exchange rack said that there are seals, deep inside. Cant imagine how they seal around the teeth on the ram though. So my boots should not have been full of oil.

 

[Ashley Burton]

Can they not just supply you the correct rack?

 

[rcx132]

Can they not just supply you the correct rack?

Don't think so. They recondition racks depending on what core units they get in. Aftermarket rack is £300 which is other option .

 

[Ashley Burton]

I would send it back personally. Worst case you could get your original rack rebuilt if its in good enough condition. Aftermarket racks seem a mixed bag if I'm honest!