Hi guys

I've got a 1996 Hilux Surf (JDM 4Runner) 2.7 5-speed.

I bought the car in a condition pretty much ready for the junkyard but have put a lot into getting it back into perfect condition.

As part of this, the steering pump was rebuilt when I first got it (new shaft, bearing, seals).

Since I owned the car (and have put about 50,000 km on it) there has been an untraceable set of noises which I am starting to think might be the steering pump.

-Under acceleration, there is sometimes (not always) a low whine / hum coming from the engine. All belts are in good condition and correctly tightened. Water pump new, new idlers for the steering pump and AC compressor, rebuilt alternator.

-When low speed manouvering, I get a very low hum when turning the wheel.

-Occasionally when low speed manouvering I bet a sudden thump which is not coming from the ball joints, wheel bearings, control arms, rack ends etc. I have never been able to race it.

I'm happy to replace the internals of the pump (pretty quick job), but I wonder if anyone else recognises these symptoms and traced them to another cause.

Thanks

EO

Steering pump/rack whining noise issues are most of the time is bad/dirty fluid. A good flush/clean and fresh fluid in most cases will take care of it. Lot of people think its the pump, but just a fluid change in most cases takes care of it. Its common on many vehicles, not just 3rd gen 4runner.
I had the same thing happen this year on my 3rd gen and the wifes Benz, both were whining, flushed fluid on both, cured both.
NOTE : My steering pump has about 370K miles on it, still works fine.

Thanks, I'll try that before throwing any money at it.

Where do I disconnect the pipes / hoses to safely drain the system?

EO

There's different ways to do it, and depending on how locked up your connections are cause you dont want to wreck a line. I was kinda lazy and disconnected the rack lines, moved the steering wheel back and forth to empty the rack. Started it up quick to empty pump. Secured connections, added fluid, ran it, turned wheel back and forth, emptied it again to flush. Then I Filled it again. Worked for me.

Thanks very much. I think my rack connections are OK. Certainly the ones to the pump are OK.

I meant the coupler nuts, sometimes they are pretty frozen and you can strip the nuts and bend the metal lines.

I'll second that power steering noises are often just old/dirty fluid. And that changing it fairly regularly (every 3 years or so?) will help keep the rest of the system in good shape.

If you have a fluid pump, just pump it out of the reservoir, remove the return line and connect that to a hose to a drain container. Turn the steering wheel lock to lock a few times (no need for engine to be running) and that will clear almost all the fluid. Draining it at the rack connections will also work but is likely to make more of a mess. Refill with Dexron ATF.

-Charlie

Draining at the rack connections is also a good way to strip the nuts!

I'd wager you can go much longer than ever 3 years with power steering fluid. Its a sealed system so the fluid should last for a long time.

It is a mostly sealed system, but there is 'breathing' through the cap as the fluid heats and cools - through PS fluid isn't hygroscopic like brake fluid is. The real issue is that it gets pumped at very high pressures (1000 PSI, give or take) and takes a beating as hydraulic fluid and there isn't a large reserve or filter in the system.

-Charlie

bought a 99 a year ago since day one it makes the slight whining noise you speak of, only really hear it when i'm stop at a red or idling somewhere. i've replaced the rack and the ps pump with new fluids and still makes the noise.

keep updated if you solve your whine issue

Thinking about it, the noise was present from the first time I drove the truck post-rebuild with fresh fluid in the power steering system. So it can't be old fluid.

Only other thing I have not replaced that could make the noise in my mind, is the fan clutch.

check the screen in the reservoir. they often times get gunk built up, and prevent the fluid from returning quickly enough. it can causes the noises you are talking about.

+1^^^
This is what causes the common buzzing whiney noise. The reservoir can be separated from the pump, and the screen at the bottom easily cleaned. There is an o-ring between the res and pump body that can be replaced (cheap part) at that time.
IMO, it is much easier to exchange the fluid by disconnecting the return line at the res than going under the car and messing with the pressure fittings on the rack.

I have that o-ring sitting on my bench, waiting for me when I clean my PS reservoir screen.

-Charlie

Do you know the part number for that o ring?