Bleeding power steering pump
 

I have replaced the power steering pump and both lines on my 72 T/A. I have been following the instructions from CVF Racing on how to prime and bleed the system, but I have not been able to purge all the air out of the system.

I have the front end in the air, and have turned the wheel slowly over 100 times and I am still getting air out. I finally fired it up and the pump is LOUD.

I ordered a power steering fitting for my vacuum pump, I will try that method next.

Any other suggestions from the group?

Following. I'll be replacing the PS pump and power steering box on my brother's GTO in a week, so I'm curious to hear what others have for tips.

Jim Shea Steering Papers;

http://jimshea.corvettefaq.com/?p=593

GM Version;

The following is taken from a GM bulletin on eliminating air from a power steering system after the system has been taken apart for repairs.

GETTING THE AIR OUT
After replacing a pump, rack or hose, you'll also have to bleed the system of air before returning the vehicle to the customer. Bleeding may also be necessary if the fluid level in the pump reservoir has gotten low and allowed air to enter the lines. Air can cause noisy operation as well as reduced power assist.
One way to tell if there's air in the system is to observe the appearance of the fluid. If an ATF-based fluid is pinkish or foamy in appearance, it's full of air bubbles. If a normally clear fluid has a tan appearance, it also contains air.
After filling the pump reservoir with the proper fluid, raise the wheels off the ground and slowly turn the steering from lock to lock with the engine off. When you reach the stop at one side, wait about five seconds before cranking the wheels the other way. Continue cranking the wheels back and forth 10 to 12 times while keeping an eye on the fluid reservoir and adding fluid as needed to keep it full. This should get rid of most of the air in the system and give you a good upper-body workout.
On some applications, you may have to use a power steering pump air evacuator to purge all of the air from the system. The tool consists of a rubber stopper that fits into the filler opening of the pump reservoir. Attached to it is a vacuum hose connected to a vacuum pump or siphon. The tool applies vacuum to the reservoir while the engine is idling to help draw out dissolved air bubbles. Cycle the steering from lock to lock every 30 seconds for approximately five minutes while maintaining 15 inches Hg of vacuum. Do not hold the steering wheel at the stops while cycling because this increases pressure. If one session doesn't completely purge all the air, you may have to repeat the vacuum procedure several times.
Finally, give the vehicle a short test drive to make sure the steering feels normal and is quiet. Check belt tension at the pump and the condition of the belt (replacement is recommended if the belt shows any physical damage, is glazed or is more than five years old).


My personal experience has shown that;
Replacing the pump would take about 30 SLOW lock to lock turns, engine off, wheels off the ground..
New steering gear and pump, about a hundred turns.
Drive around the neighborhood with a few slow speed lock to lock turns in a church (or empty) parking lot in each direction and then let it sit overnight. Check level in the morning.

the steps in post #3 should work...

what i have always done at home with new pumps is to fill the pump to proper level then manually turn the pulley the opposite way of operation for awhile, a few minutes if doing by hand or rig up a drill to turn at moderate speeds, you should see some bubbles coming up in the fluid. let sit for awhile if aerated too bad. then turn it in direction of operation the same way as before watching for bubbles & topping off as needed. then do as explained above by turning wheels lock to lock with engine off & watch for bubbles & top off, if fluid is aerated too much let sit until bubbles settle.

i then start the engine with the wheels still off the ground, it will usually make some noise at this point, turn the wheels lock to lock one time & check fluid level & for bubbles... the fluid will usually get a lot of bubbles this first time so let it sit again until they clear up. repeat this cycle until the bubbles clear up & the steering wheel turns smoothly with no noise.

it took me 4-5 cycles with engine running to purge all the air & get a quiet smooth operation but the initial turning in reverse & operating direction by hand seemed to get a lot of the bigger air bubbles out & helped a lot with the rest of the process. cant remember where i heard about the reverse turning, maybe came with the pump instructions or a mechanic friend of mine told me. either way ive had good luck doing it that way on a new/reman'd pump.

Cranking it back and forth only gets some of the air out, the pump gets the rest - it is probably loud because the fluid is way low now.

I have been checking the fluid level closely, topping it off when needed. So that is not the issue.

I think I will try spinning the pump by hand in the opposite direction, and then applying a vacuum while running.

spin reverse & forward by hand for awhile & watch the fluid for bubbles or to make sure its circulating. cant say that will fix your issue but it worked great for me along with the other steps... only made noise for a short time on the initial start up & frothed the fluid pretty good, let it sit overnight to clear up the bubbles & worked fine after that.

i have read many issues with reman'd pumps & some guys had to replace the defective ones they got in order to get a good working one. i used a cardone from rock auto that worked great right off the bat & is still going strong after 6 years of use & lots of high rpm drag runs.

Have been down this road and ended up putting a vacuum on the pump assy over night a few times.
Also I have found a rebuild didn't put the pressure spring ball in the Pressure side and the system couldn't purge the air
because it couldn't hold back the fluid in the pump ( which is done for pressure reasons)
Another pump ( just the pump, not reservoir) fixed this issue.
I assume your pump is a rebuild?

Having worked in a few GM dealerships, the method we used was similar to the instructions in Post #3. Letting the car sit will many times let the air bubbles out of the fluid, that cause the growling from cavitation.

There are more methods that are used, by more techs, turning the box to the locks, and overriding the relief valve works for some, by bumping the stops repeatedly, works too in certain situations.

With any hydraulic system, if it draws any air on the suction side, it's putting air back into the system as fast as you bleed it out. Hoses and connections need to be sealed before elimination of air in the system can be purged. I have seen older suction hoses that will suck air through the hose material as they deteriorate, they don't leak oil because they are not usually pressurized.

Not a bad idea to replace older return hoses if they show any sign of deterioration.

For what it’s worth I ran into this issue a few years ago after rebuilding (resealing) my power steering box and I believe I replaced my pump at that time as well. Anyway, I used a combination of the methods mentioned above. The only exception to note is the rubber insert used in order to pull a vacuum on the system doesn’t work due to the notches on the inside of the reservoir opening. It won’t seal obviously (assuming yours is the same as my 77). I ended up picking up another power steering cap and installed a fitting into the center of the cap to hook a vacuum hose to. Little RTV to help seal the fitting, and I think I cut a new gasket out of cork for the cap if I remember right, and got a nice tight seal I could use to apply vacuum. That seemed to make quite an improvement but I had also turned lock to lock as described above a LOT.

I did have a bit of a loss of power assist at hot idle for several drives after, which was I assume more air I couldn’t evacuate, but that ended up working itself out.

Good luck!