power steering pump whine

Hi, I have a '98 tacoma 2.7/4, 4whd. replaced steering rack, outer tie rods, pressure line, steering pump, o ring between pump and reservoir. Filled w/ dex/merc fluid, turned wheel back and forth 8 times while jacked up. Started truck, turned another 8 times. All seemed fine. Started driving, After 5 min., pump began to whine. Turned off truck, opened reservoir, fluid foamy(actually had leaked out of reservoir cap and was pooled on top of reservoir. Any thoughts? Thank you, lhc

 

Thanks for the reply, Jamesboy. I didn't know there was a breather in the system. Is it part of the reservoir cap?

 

I had the same foaming issue with my 99. The foaming is from air in the steering system. If it remains after purging and driving, or like mine, goes away then comes back when it gets hot, there is a leak on the return side.

I replaced the return hose, and it still foamed. After a lot of looking and trying, and 2 pumps, I finally saw the little 4" piece of hose that went from the rack to a hard line. That hard line went to the longer hose (that I replaced) that goes to the fluid reservoir. For me, replacing that stupid little bit of hose fixed it for good. By the way, I didn't have any leaks that indicated the hose was bad, but I guess when the fluid heated up and softened the hose it let in some air.

Long story short, check/replace your return hose(s).

 

Thanks factol,
I've replaced the pressure line and both
rubber sections of the return line(w/ new hose clamps. Also added inline mag. filter. My reservoir doesn't have a screen(I can shine a light from the top and see the reservoir outlet at the bottom). I did notice the metal section of the return line below the radiator is corroded and pitted. I removed it, cleaned it up and didn't see any holes, although I was suspicious. It doesn't appear to be leaking but could it be sucking air in? I guess the remanufactured pump I installed could be bad. I do still have power steering but noisy and fluid foams within a few minutes of cold start

 

The screen in the reservoir is there to prevent foaming, it acts as a flow straightener. Without the screen, turbulence of the fluid causes it to entrain air and foam up.

Some people have jury-rigged a screen that seems to work. Other than that, replacing the reservoir is your best bet.

 

Thanks for the reply - that makes sense to me. I'll order a new pump w/reservoir, install it and report back. I think I'll replace the steel part of the return line for good measure

 

I was having a PS whine on my 99 and it got louder and louder. Bought a replacement pump. Still the same whine. Turned out being the idler pulley bearing close to the pump. Fooled me and others. Easy and cheap fix.

 

That's interesting. It reminds me to keep an open mind when trying to diagnose mechanical problems.

 

My reservoir doesn't have a screen either. I kept thinking that was the problem and tried a few things that I thought helped for a while, but turned out they were just wishful thinking. I was convinced that swirling of fluid in the reservoir was where air was getting in. I personally don't think the screen matters much, or at all, with foaming. After I replaced the bad return hose I've have no issues with a screen-less reservoir.

I tried a vacuum test when it was cold, used a mightyvac and pulled a vacuum at the reservoir. When the engine was cold it held the vacuum, but when I got it hot it kept dropping it.

From everything I read, if the pump whines when cold after you've purged all the air from the system you could have a leak anywhere or a bad pump. If it only makes the noise after it gets hot, it's most likely on the return side, sucking air in. And it can suck in air without leaking any fluid. I had no fluid leaks.

If cold, make sure you check at the connection to the pump, that you used 2 new washers and tightened to spec. Check that valve that goes to the engine to increase RPM too. I think when they go bad you can find fluid in the air line to the engine.

If only when warm check out everything on the return end. All lines on the rack tight, the mag filter, all connections and hoses.

I feel your pain. I chased the sound for months before I got a permanent fix. Hopefully it's an easy fix when you find it.

 

Thanks for that very informative reply.
I've replaced the rubber return hose sections and have ordered the metal section, since it is quite corroded and pitted, could be sucking air. My current pump, which is a mnf.rebuild from pep boys, starts whining less than 5 minutes after cold start(it could be bad). When I look in the reservoir, fluid is foamy. I did install an inline mag filter(the kind which comes apart for service) Wonder if they ever leak. I also wonder why some reservoirs have screens and some don't. Good idea about the mighty - where did you get that?

 

Mityvac MV8000

$52 Mityvac MV8000 Automotive Tune-up and Brake Bleeder Kit, Selectline Hand Pump (MV8010), One Finger Vacuum Release, Ergonomic Design, Gearless Diaphragm Gauge, 4.5oz Fluid Reservoir, 4 Tapered Adapters

https://www.amazon.com/Mityvac-MV8000-Automotive-Test-Bleeding/dp/B00265M9SS

They make a power steering adapter, but I don't think it works with the Tacoma reservoir, because of the cutouts in the inside lip. I just used a rubber foot/pad that I had bought to put on my air compressor. These are what I used, but just because I had them on my workbench. I put some atf on the bottom and held it against the reservoir opening while pumping until it made a seal:
https://www.amazon.com/AmplifiedPar...pID=41ziMzVAXdL&preST=_SY300_QL70_&dpSrc=srch

Anything that would make a decent seal over the top of the reservoir should work, that has a hole in it for the tubing of course. The cutouts on the inside of reservoir lip (red) make it so you can't use a plug that goes into the reservoir. I thought I could just use a plug on the inside opening (yellow), but that inner part must not be an airtight seal because I could never pull a vacuum that way.

 

Thanks, I ended up installing a new pump/reservoir(Atlantic from APX parts). I also installed a new return line (a complete Sunsong unit with steel and rubber ends already attached. Then I bled the system by turning the wheels back and forth with the engine off until most of the air bubbles were gone. When I test drove it at first the truck seemed to want to "steer itself". I had to hold the wheel to keep the truck from turning. When I tried to unscrew the reservoir cap, it was held on by a slight vaccum pressure(that seemed strange). After driving around for a couple minutes, it seemed to steer normally and the cap came off without vaccuum pressure. No more whine or air bubbles in fluid. I don't know if replacing the pump or the return line did the trick. One thing I noticed before I relaced the pump and line: when I removed the cap on the reservoir with the engine running, the fluid was swirling around in a vortex. After I replaced the pump/reservoir and return line, the fluid was no longer swirling around or appearing to move at all. Whether this indicated a bad pump or leaking return line, I don't know.
Thanks to all for the help!

 

Sorry to bring an old thread back from the dead. I guess I will be testing the theory today about whether it's the power steering pump, or the return line.
Long story short, lost all my power steering.

After a couple flushes, I cleaned out the reservoir (have a tear in the screen around the edge of my reservoir, but got it cleaned up)

Replaced the power steering pump with new Cardone pump (no joy)

Replaced the rack & pinion (now power steering worked, but endless whining and bubbles)

Rebuilt the oem power steering pump and go my money back from the new one I purchased (same whine, but power steering works great)

Went to put in a magnetic inline filter today and saw this (pic below probably). Return line was wet with goopy drippings on the radiator hose and alternator. Took two weeks for that amount of leakage to be found. Cleaned off the hose and drove around for half an hour. Came home and found two new drip's on the lower radiator line. Felt the hose and low and behold, very small wet spot on my finger.

SO, I'm going to NAPA to buy a generic return line hose for $15.
My guess is what happened was I got some cracks in the hose from clearing out my line over and over again. I would disconnect the upper portion of the hose, fold it in half with a 5 gallon bucket underneath, lift up the truck, and turn the wheel until there was no more power steering fluid leaking out...
HOPEFULLY this works. If not, then we will know our answer that it's probably the mesh inside the reservoir. I've checked most of the metal parts of my return line and I'd say they aren't the culprit, but I'll keep my eyes open.
Kinda tired of lifting the truck up and trying to bleed the system.