Power steering

I just replaced the power steering pump on my 97 Tacoma, but I'm still having an issue. When everything is cold the power steering works great but when everything warms up the pump starts to moan. With the cap off the reservoir at start up the fluid looks fine, but once I hit operating temperature it looks like a cyclone sucking fluid into the pump. The screen in the reservoir has been removed and an inline filter was installed. After a short drive, it looks to building up excessive pressure, after it sits for 30 minutes or so there will fluid on lid to the reservoir. I've jacked it up turned the wheels lock to lock many times trying to get any air bubbles out, but no luck. Any suggestions.
Thanks,
Jeff

 

I was able to clean my screen with a small brush, then flushed the system -- fixed the moaning. I bought an inline filter, but was concerned that it would get clogged and over pressure, so I didn't use it; maybe check and see if the filter is clogged?

 

Filter is clean. Only makes noise when it gets hot, when it gets hot there are bubbles in the reservoir. System was bled tonight still have the same problems. Any suggestions on where to look for air leaks?
Thanks

 

The only suction point I can think of is at the o-ring between the reservoir and the pump; if you're not seeing leaking there, I don't see air being "sucked in". Did you replace the o-ring? The only other cause would be cavitation, where the pump is stirring the air in. If you're confident fluid is moving through the system, maybe the noise isn't connected to the air bubbles?

Hints (maybe obvious):
Hot = lower viscosity fluid
Cold = Higher viscosity fluid

Mine made noise cold until the fluid warmed up enough to get through the clogged filter. Maybe there are other features in the filter that streamline the flow into the pump, preventing the "cyclone"? I watched a video of removing the filter, and there were other features and shapes on it.

 

I never thought of that, but I bet you are correct. If I get home early enough to tomorrow night, I will put something in the tank to obstruct the fluid. Thanks for the information.