Tiny bubbles ...

Tiny bubbles in the wine, make me feel happy, make me feel fine. (Don Ho song)
Tiny bubbles in the power steering fluid, not so much!

I had a failed CPP 500 steering box, which I replaced with a new one. On the original box, I filled it with PS fluid before the first start up. I didn't do that this time and have frothy PS fluid. Maybe it was my attempt at bleeding that was the problem. With the front end in the air, I started the car – had a leak, shutdown, got that fixed. I added some PS fluid, started the engine, and rotated the steering from lock-to-lock a number of times. I checked the PS fluid, and the fluid was frothy. Drat. I left the cap off the steering pump overnight, and the next afternoon, the bubbles were gone from the measuring stick. I think I did the bleeding wrong, should have rotated the steering with the engine off? Later, after adding some more fluid, I rotated lock-to-lock 10 times with the engine off (and the cap off the PS pump), and the stick was frothy again. What do you advise I do to get rid of the froth (I assume the bubbles will come out of solution with time, but maybe not?), and how to better bleed the PS?
Thanks, Doug

The othe day my BIL and I installed a Reman early 80s C10 PS box on his 70 C10. We bolted new box on and turned it lock to lock while checking fluid and toping it off. Went for a drive and it drove great, went home checked fluid still good, called it done. Do you have any leaks that might be sucking air?

Hi Mark,
I admit, I have been looking more at leaks that push fluid out, and have stopped the one leak that was doing so. Dumb question, but, how would I spot a leak that is sucking air?
Thanks, Doug

Thing is, you won't directly detect a leak that's leaking air into the system. It's very unlikely anyway.

What I would do is start over with the fill and bleed procedure. Jack up the car to where the front wheels are off the floor. Fill the system so that the reservoir is at its normal "full" level. With the engine off, turn the steering wheel through the whole travel 3 to 5 times, checking the level as you go and top it off. Start the engine and check and top off the level again. Now you can start the engine one more time and repeat that whole procedure of going through the full travel 3-5 times, again topping off the fluid as needed. If you have any foaming, stop and let everything rest overnight. If that doesn't do it either the box or the pump is faulty.
'

Thanks Rick,
I will do the fill & bleed process again, like you said.
Thanks, Doug

Hi Rick,
I did the process you listed, but added a suggestion from a long-time mechanic friend. When he was in the business, he would disconnect the coil wire at the distributor so the engine wouldn't start and would crank the engine while doing the lock-to-lock turns. The bubble issue with the PS fluid is gone. :) Thanks for your help! Thanks, Mark, for your thoughts on the issue.
Regards, Doug

The only comment I'd make on that is that it's very easy to overheat the starter when doing it with the coil wire pulled.

Glad you got it done.

Never had many issues with bleeding ps systems, a few with snow plows and a ton with my under lift tranny jack that I cannot seem to work the air out of. I am not sure why you would worry about the motor starting while working the wheel. But who cares at this point the important thing is you are done.

If the engine is running (or spinning) then the PS pump is running to pump fluid to the rack/gear...
Agree with Rick's comment that you should NOT over run your starter to spin the engine it can overheat and might fail... :)
unless you remove your plugs also, in which case the starter can spin the engine much more easily...

I rather liked the concept of slowly engaging the PS pump while rotating the box to move fluid (and air) thru the complete system in order to bleed the system, without the engine running the PS pump at a fast rate. My first attempt at bleeding the system was with the engine running, rotating the box lock-to-lock, front end in the air, where I ended up with frothy PS fluid. I appreciate the concerns expressed about extended running of the starter. I understood the danger of extended starter running, so I would crank and turn about half a turn, immediately stop cranking, move my hand to a new position on the steering wheel, repeat, etc. I only went lock-to-lock 2 times in spurts, with time between the two sessions where I checked the fluid level. Between those two things, I figured I was not overtaxing the starter.
Thanks for the discussion! Doug