GM...I have 71' Cutlass 455 that suddenly developed small steering issue when car is warm and at idle, low rpms...steering becomes very stiff when turning wheels. Rev RPMs, or start driving it becomes normal again. Was brand new pump 2014 with maybe 300 miles on it since then. Used turkey baster to replace PS oil in canister once in that time.

It doesnt do it when car is cold. Lifted front end off the ground and it doesnt do it either, at idle or warm. So only under a load on the ground, low rpm/idle, and warm.
Any help appreciated. JC

 

Does the pump have a warranty?

Make sure your PS belt is tightened.

 

While this may or may not be the issue, I've had a loose flow control valve cause this problem. The flow control valve is underneath the outlet fitting on the back of the pump. The adjusting nut can come loose, causing low pressure.

 

Well, I have had issues with belt being tight enough in the past, finally got that pretty much settled while ago, but even before when it was a struggle getting it tight enough to get rid of whine at higher revs, it never showed this issue.

 

I was aware of the this valve, but not that it can loosen...will check tightness tonight and report back. Thx.

 

Tried to check tightness, but couldn't get a wrench on it enough to turn valve nut. Big *** wrench needed. Didnt seem enough room to use crescent wrench. Have to try again after current project.