Power steering; low assist early after startup

[Belair-o]

Hi TriFivers,
I have an issue with the CPP power steering system in my 57. Upon starting the car, assist seems to now be initially nonexistent. After running for a while, I do get assist, but not sure it is full assist, though improved. Immediately after installing a replacement 500 box, all was good, but not now. I lifted the frontend, and bled the system again, but didn't help. Fluid level is right on. The PS pump is GM from a GM serpentine belt kit I installed. Any thoughts?
Thanks, Doug

[55 Rescue Dog]

With the serpentine belt, does it reverse the rotation of the pump?

[Belair-o]

With the serpentine belt, does it reverse the rotation of the pump?

55 RD,
I am not sure, but, the PS pump (and alternator, AC compressor, water pump) all came as one complete GM part system. The PS system had good assist when I first put in my replacement 500 box, but is now having issues.
Thanks, Doug

[Rick_L]

The problem is likely in your pump. Perhaps the pressure relief valve is hanging open or leaking.

[Belair-o]

The problem is likely in your pump. Perhaps the pressure relief valve is hanging open or leaking.

Hi Rick,
Thanks for the reply. Is that something I can fix, or is replacement the best way to eliminate the problem?
Thanks, Doug

[Belair-o]

Okay, I guess from internet searching, I remove the high-pressure line, try and capture the PS fluid that will leak out, remove the fitting the high-pressure line connects to on the PS pump, stick something into that port, and see if the pressure relief valve is hanging up. Assuming I get the valve to move freely, connect up the stuff I took off, add some PS fluid, and go thru the bleeding process?

If the valve isn't hung up, I guess I assume a leaking valve, so remove the valve (how does one remove it, and can I remove it while the pump is installed on the engine?), and get a replacement valve?
Thanks, Doug

[Rick_L]

The valve screws into the back of the pump and is the port where you connect the high pressure line.

Blocking that port does you no good, as moving the steering wheel to full travel one direction or the other does the same thing. Also you need a pressure gauge to do this diagnosis. Don't let the system run at full blocked pressure for more than a few seconds as heat builds fast.

[Belair-o]

Hi Rick,
Wasn't planning on blocking the port. I was figuring to see if the valve was stuck - if so, see if it will free up. I guess if it isn't stuck, the next hypothesis is that the valve is leaking, hence the pressure gauge you mentioned? Alternatively, would it make sense to just replace the valve, and put it all back together?
Thanks, Doug

[Belair-o]

Bump

[Timmins57]

I have the same problem with mine. Installed the new box and pump and it worked great the first trip. The next day it was as if there was no power steering when I tried it. Bled the system a few times and it seemed better.
We then went on a road trip and it would be stiff in the morning and it seemed as if it had to warm up a bit then ran great all day. We did a 3200 km trip and it worked great except for the morning stiffness.