Power Steering Riddle

[Derick]

I'll ask a dumb question. Have you re-greased your intermediate steering shaft?

I ask because when I got my suburban I SWORE I had a bad PS pump. Turned out it was the intermediate shaft. Jam the grease gun up there, fill it up, and then pull off the rubber boot at the firewall and grease that up too. Mine was like new in no time. Seems like a simple easy thing to check, because mine was bone dry.

 

[thompsoj22]

the pump is submerged and in no way "pulls/siphons" fluid from the system. If there is air it would likely be caused by a "vortex" in the fluid resevoir allowing the pump to ingest air. have someone in the parked vehicle and simulate freeway rpm while you watch the fluid in the pwr steering tank circulate. is the fluid swirling or relatively calm as it should be, is the fluid aerated? bubbles on the dip stick?. i think your correct with just a bad pump. a slow/obstructed/kinked return line would also allow the pump to cavitate at higher rpm.

 

[SnowDrifter]

Rather than speculating if air is in the system: Visually check if after you're done driving. While you're there, humor me and check fluid level once more.

Low fluid will introduce air into the system. And, I know this is counter intuitive, so bear with me: So will too much fluid. Couldn't tell you why or how, only that it can and does happen.

 

[NGAneer]

First off, thanks for the help guys. Answers below.

I'll ask a dumb question. Have you re-greased your intermediate steering shaft?

I ask because when I got my suburban I SWORE I had a bad PS pump. Turned out it was the intermediate shaft. Jam the grease gun up there, fill it up, and then pull off the rubber boot at the firewall and grease that up too. Mine was like new in no time. Seems like a simple easy thing to check, because mine was bone dry.

Did not think of this. I'll have to say that the noise is definitely in the pump. Mechanics stethoscope got me there. The noise also changes tone with engine RPM. Good thought though.

the pump is submerged and in no way "pulls/siphons" fluid from the system. If there is air it would likely be caused by a "vortex" in the fluid resevoir allowing the pump to ingest air. have someone in the parked vehicle and simulate freeway rpm while you watch the fluid in the pwr steering tank circulate. is the fluid swirling or relatively calm as it should be, is the fluid aerated? bubbles on the dip stick?. i think your correct with just a bad pump. a slow/obstructed/kinked return line would also allow the pump to cavitate at higher rpm.

I did think of this. I don't see a lot of bubbles and I don't see a vortex at the ~1500 rpm at which I tested it. I might try a larger RPM range to see if one may be worse than others.

Rather than speculating if air is in the system: Visually check if after you're done driving. While you're there, humor me and check fluid level once more.

Low fluid will introduce air into the system. And, I know this is counter intuitive, so bear with me: So will too much fluid. Couldn't tell you why or how, only that it can and does happen.

Fluid level is absolutely not the problem. I only say that because it was the first thing I did before changing any parts and have done consistently since.

 

[exp500]

Three questions, what power steering fluid or ATF? Is return hose higher than pump anywhere? Can you hear the relief valve Pop when you turn wheels to the stops? 1) foamy oil, 2)sucking air at retun line. 3) relief valve stuck open. Hope this helps.