PS Pump airlocked?

[Mac]

`78 C-10 ReManu pump and mid 70's C-10 junkyard steering box for my `63. Fresh Valvoline PS Fluid. Pressure hose is routed to the smaller, forward port on the box.
I expected to have to get air worked out of the system with "wheels up - turn lock to lock multiple times" method, but within second of the engine running the pump seems to bind and the belt squeals badly. Fluid is frothy.
Question is: can air in the system cause this kind of binding?

[enjenjo]

No, but lines hooked up backwards can. The pressure line is the one toward the front of the truck on the box.

[Mac]

The pressure line is the one toward the front of the truck on the box.

That's the way I have it.
So, should I be considering things like defective pump or bad box?

[enjenjo]

The pressure line is the one toward the front of the truck on the box.

That's the way I have it.
So, should I be considering things like defective pump or bad box?

The problem you have is caused bt an obstruction in the line. When working properly oil circulates through the pressure line, and returning through the return line without doing any work. When you turn the wheel, this opens a valve diverting some of the oil to push on a piston assisting the steering. When you stop turning the wheel, the valve closes, and the oil bipasses again.

If the lines are hooked up backwards, I know now your's are correct, there is a check valve in the box that becomes the obstruction. If the lines are hooked up right, there is another obstruction. I would think that you are using new lines, so we can rule that out, unless there were plugs in the new lines that were not removed before installing. I have also seen plugs installed in the pump return line fitting to keep out dirt during shipping, another possibility. The other possibility is the box itself, there can be crud in the box from it's days in a junk yard.

To test it, connect the pressure line to the return line, bypassing the steering box. Start the engine, at idle only, and the pump should run fine, no noise. If it makes noise, it's the pump, or lines. If it's ok, it's the box.

One more thing, on some OE style lines, they have one or more collars crimped on the pressure lines. These are for controlling hose jump on long lines. If it's a used hose, the collars can rust on the inside, closing off the hose, at least to the point that the pressure increases and makes the bypass valve in the pump open, causing the squeal.

[Mac]

OK, I'm an IDIOT.
Checked after work and I do, in fact, have the lines backwards. Was sure I remembered reading, a couple of places, that the smaller port on the box is the pressure side and I also went and found a pic of the hose routeing on the pickup forum of Chevy Talk. While I didn't just guess at the hook up I managed to get it wrong anyway.  :oops:

Thanks Frank for your in depth replies. The first short and sweet reply: "ya got it backwards, dummy", would have been enough afterall.