power steering foaming

[greenvilledave]

Putting truck back together and after trying several things the fluid still is foaming out the cab hole. started from dry with atf and it foamed now trying power steering fluid. should we keep moving from lock to lock. Does not leak anywhere else in the system. 69 c10 with 350 power steering system came from a 71 ANY HELP would be great Dave

[dennislbrooks]

As I understand the procedure is ---- before starting with clear fluid --fill to proper level. raise front to lghten steering ---- start and turn from side to side gently to the stops. Shut off and let clear again--refill --- start and side to side. Repeat until fluid level remains and is not cloudy. I had the same thing when I put my hydroboost on.

[hotrodhomi]

remember to not overfill it

[Woody]

Drain it and refill it with Pwer Steering Fluid "NOT" ATF. ATF is not for power Steering Pumps. PS runs at a higher pressure and makes ATF foam (of course you have discovered this by now).

I have worked on Cars & Trucks since the 70's and always thought ATF would work in PS pumps. I found out about 18 months ago that it won't. When someone told me it wouldn't work, I said 'But it says on the cap to use type F ATF'. He said the higher pressure causes it to foam. I, as you have, found out the hard way. I used a Suck Gun to remove as much as possible and refilled with PS fluid. No more foaming............


Woody

[Longhorn Man]

While what woody says is acurate for newer cars, these old things were built with lower pressures and the tranny fluid does have anti foaming agents in it.
Personally, when ever I replace a steering gear box, I'll fill the pump up all the way to the top. I'll jack up the fromt, and with the engine OFF, I will crank it back and forth lock to lock a few times. Then I'll check the fluid. Generally, I need to add some to bring it to the full line. THEN I fire it up, let it idle sitting without touching the wheel for a moment. Then I'll start cranking the wheel. If it groans loud at any point, then shut it off and crank it by hand again.

By cranking it by hand, you are filling the system without the pump running dry. This extends the life of the pump, creates little to no foam, and I have found it to be quicker.

I do this every week on the trucks we rebuild at work. We turn out one 95 or 96 Chevy P/30 a week, and they get new steering gear boxes, pumps, and lines... so I know we are dealing with a dry system. I found that by starting it up dry, the fluid will foam....atf, or steering fluid. Either one. (yes, in the new high pressure cars, the ATF DOES foam more)

I used mobile one synthetic tranny fluid in mine, no foam in any way, shape, or form. Good stuff.

[Green Machine]

Leave it sit overnight, the foam will settle down, then do the jack and turn thing, filling as you go. When you are sure all the air is out then start it. Dexron ATF works good for me in the older stuff.