Power Steering Issue

[MrFiveOh]

My truck is a 74 C10 SWB 350/350.

Initially I found my gearbox was leaking and I replaced it. I later found out the P/S pump and gearbox was from an 81. I decided to get a new pump as well since it was unknown how old the pump was along with new hoses and a new rag joint.

I installed everything and learned the pump was no good, got a new one and P/S worked.

So here's my issue. In town P/S is wonderful steering is solid making turns smooth. Upon driving a good 10-15 min straight without making a regular 90 degree turn I lose P/S. If driving for a good distance without turning and come to a stop P/S is gone, as I start too accelerate and start my turn it's stiff and then P/S kicks back in and is good again until a long straight again.

I bled fluid both times I put a new pump in. I'm lost as what it wrong. I've lifted my truck and went lock to lock multiple times.I've done it with the truck on and off.

[jg1977c20]

when you bleed the air - lock to lock make sure you leave cap off if u already didn't - another option is to jack the front end up so the wheels are off the ground - and re-do the bleeding this works best on alot of trucks -

- belt needs to be real tight

- could be a problem in the steering box itself -thats where the hydraulic valves are that open and close to create the pressure - the pump is just that ( a pump ) .   good luck

[MrFiveOh]

See I was told the box can be the issue also, something about the valve assembly not being properly put together. Considering the pump works when I'm turning through the cirt, but once I hit an open road for an extended period of time is when the issue arises.

Cap was off and I had it hacked up. Also belt is tight.

[Irish_Alley]

i just had an issue with a 2002 chevy that i just got. the power steering would only work while turning left. if you turned right there wasnt no assist, the gear box was my problem.
but when you lose power steering does the pump whine or anything?
any air bubbles/foam in the power steering reservoir?

[LTZ C20]

It seems that both turning directions work until you drive straight for awhile. I would flush the entire system of power steering fluid out and replace with GM Dex 6 auto transmission fluid. If that doesn't solve the issue, then I sounds like valves inside the gear are sticking. Also, what are your answers to Irish's questions?

[MrFiveOh]

Sorry for delay, so the issue was the gear box. Got a new one on and works really good. Thanks for the help.

[Captain Swampy]

Thanks for letting us know what fixed it.