Filling the power steering on 71 bigblock

[xs-cash]

My 71 bigblock has been apart for yrs, I’m putting her back together , I seem to have trouble filling the power steering pump , it seems like it’s air locked or something, I can fill the top tank ,it doesn’t seem to be going into the pump on the motor, it’s running and I’ve got it jacked up ,turning the wheels slowly, jus seems to be takin for ever to fill , how to I get the air outta the system?

[Richard]

Cycle the steering with the engine off, can be easier with the front wheels off the ground. Maybe double check the supply/return lines to the box as well.

[xs-cash]

Originally Posted by Richard

Cycle the steering with the engine off, can be easier with the front wheels off the ground. Maybe double check the supply/return lines to the box as well.

I will try that tomorrow. Thanx

[71CHEVYSHORTBED402]

Funny this came up, I came to the board thinking about a post for this. I rebuilt my 402 truck from the ground up and hired a shop for the maiden start. He rebuilt the carb and scored me a choke, and I stop at tuning carbs, for now. Got to have a runner to bleed and prime, so they did that as well as prime the engine first. I asked them to prime the power steering per the recommendation of the guy who rebuilt the box and pump, but then they've been doing this for years.

Then again I don't know what they did, because the steering box sprung a leak day one, and one day it was BAD. Oh snap, a do over at some point, gross. Wouldn't be the first a seal or o-ring went bad here, it's dry and a lot of my parts sat around a while. Anyway, I thought to prime the system "again", did this and wow, the leak quit.

Jack up the front and remove the reservoir cap, fill it up to something reasonable, check often and fill as needed.

Turn wheels stop to stop, many times, some say 30. If the fluid is milky or bubbly let it settle before starting over again. I ran additional sequences with the front jacked up and the engine running, just cuz.

Drop the truck, run engine and same as above. Install cap.

Not sure why, but the rebuilder didn't suggest running sequences with the tires off the ground, first...............hmm. On a side, FWW, the rebuilder says do not use synthetics, the seals can't take it. I used ACDelco ATF Type III, though Dexron IV is another option for non-synthetic.

[Yamariv]

I just added power steering to my L6 250. Turn the wheels lock to lock several times w/o the engine running first. I starter mine up and it was squeeling like crazy no matter what I did, frothing everywhere. I turned it off, primed it with the steering wheel left and right several times and all the air came out. Good to go after that!

[71CHEVYSHORTBED402]

Originally Posted by Yamariv

I just added power steering to my L6 250. Turn the wheels lock to lock several times w/o the engine running first. I starter mine up and it was squeeling like crazy no matter what I did, frothing everywhere. I turned it off, primed it with the steering wheel left and right several times and all the air came out. Good to go after that!

Right on. Seems like there are different ways to prime it, just get her done. This was the recommendation by the guy who rebuilt my box and pump. I did this and more as mentioned above.

“DO NOT turn the steering wheel until the system is completely full. Use Dextron III ATF. DO NOT use clear fluids or synthetics in older systems. Tires should be on the ground. Fill the reservoir, then start the engine for a second and shut it off. Check and refill the reservoir. When the reservoir is completely full turn the engine on, and turn the steering wheel SLOWLY. If you hear the pump groan or moan then turn the engine off and check the fluid again. Start the engine and slowly move the steering wheel back and forth to expel air.”

Note Dextron III ATF is no longer available.

[72SB]

I just had a shop replace my gear box and watched. When he filled the pump I asked if he wanted me to jump in cab and turn wheel. He said no, he had wheels off rack and by hand just turned steering to lock one direction slowly. Added more fluid, repeat turning wheel to lock opposite direction. Said it takes a little time for the fluid from pump to "draw" into box and air to purge out. He dd the engine off, turn steering by tire by hand about 6 times before starting and then turning steering lock to lock and topping off fluid. Had to add more fluid after test drive. Not much but did add some. Said it takes a short drive to finally purge all air out.

If original style pump and box, use ATF, not PS fluid.

[RichardJ]

Vacuum Bleed

Power steering systems when vacuum bled is the safest and actually fastest way to bleed the system. There are kits available with adapters to fit a variety of reservoirs. A collection tank should be used to keep from sucking fluid into the vacuum pump. Your hand pump may have included a flat rubber fitting, but it will only fit small reservoir openings.

I think the newer, modern pumps used with remote reservoirs and rack & pinion are more susceptible to damage when the engine is started with air in the pump.

[xs-cash]

I ultimately disconnected the hose on the pump and filled it , then replaced the hose ,added some dexron , with the truck up in the air rotated the steering wheel back and forth many times , it seemed to purge itself then , works great now, thanx for the replies guys

[Steeveedee]

It's in the older repair manuals- tires should be off the ground if the vehicle is sitting in one place when running the steering right and left, to avoid making flat spots on the tires.

[damnyankee36]

Originally Posted by RichardJ

Power steering systems when vacuum bled is the safest and actually fastest way to bleed the system...

Agree. I use an AC vacuum pump. Extremely fast getting all the air out.

[Steeveedee]

Originally Posted by damnyankee36

Agree. I use an AC vacuum pump. Extremely fast getting all the air out.

I'll have to remember that trick. I happen to have a vacuum pump from an automotive AC service machine.

[RichardJ]

I have an AC vacuum pump, but a hand vacuum pump works just fine. Simple, easy and doesn't weigh as much as that old AC pump.