I went fishing this afternoon, and after starting the truck up I heard a noise that I have never heard before. So I drove a few miles and stopped to check it. It sounds like a low pitched whine. You can hear it while parked and idleing. It does sound like its coming from the power steering pump area, but honestly its hard for me to tell even when putting my ear right next to the pump. The fluid was a little low, so I stopped by a gas station and picked up some dextron III and filled it. No change. The thing thats throwing me off is that the whine increases at least for a second when accelerating from a stop. It almost sounds like a low pitched turbo for a second, and then tapers off. Would that be the case with the power steering pump? I also noticed a burning smell from the engine bay that Ive never smelled before.

Coolant, trans fluid, engine oil are all good. I have changed my steeing rack twice with remanufactured crap and Im wondering if that is the cause. I have the pre 99 rack before they switched to the rack guide and the current rack had a lot of play in it (literally from the moment I installed it). So I tightened the roller guide to eliminate the knock on the driver side of the rack. Tightening it really pinches the shaft and you can feel it in the steering wheel. Im wondering if this extra tension causes the pump to work signifiantly harder and has led to it going bad.

But based on my description in the first paragraph, does this sound like a bad steering pump?

Power steering pumps in toyota's are for life. Have you replaced the drive belts? Perhaps the sound comes from it. If you haven't replaced those, try this. Pour some water right on the belt and start the engine. If sound disappears, your problem is with the belt.

Now to the steering rack. Like I always say, good used toyota parts are far more superior than any re-manufactured or aftertermarket parts.

You can try pulling 1 belt off at a time and troubleshoot what might be causing the whine.

I recently heard this on my runner too. I thought that it was something with the transmission, but it sounds reasonable to think that it is the power steering. Every time I turn the wheel to the max, I hear a squeak. Pretty sure that it is the power steering belt slipping. I'll try tightening it and see if that does anything for the humming sound.

Good advice, however I would recommend WD-40 instead of water. PS pumps are also not really "for life" but the 5VZ pump is well built with a great life span.

Also good advice, though this only narrows it down to the belt and the accessory, not one or the other.

If you take all 3 belts off and the noise is still present, its time for a timing belt/water pump/idler bearing/tensioner bearing change

yeah PS pumps are not a lifetime part, i have burned through one in my rig. so it could be going bad. but when mine went bad there was no whine or anything it just died. as far as a rack goes, id get a Safari LTD rack, its a OEM rack, just with brass bushings/sleeves instead of the stock nylon bushings/sleeves. guys who build the Icelandic trucks use these racks with their big 44"+ tires and they hold up just fine. i think you might have over tightened the roller but thats only a guess.

Yeah, I learned this right after buying the thing.

No part is a lifetime part though. Anything can break or wear. I know Toyota calls the fuel filter a lifetime part and Im pretty sure most of us have replaced ours after seeing those pictures from whoever it was that cut his open and showed the sludge in it. And with how tight I have the roller/guide adjusted on the rack, I could see it leading to the demise of the pump.

Ill try these diagnostics. I sure hope its not the timing belt/water pump as they were changed 40k miles ago. I should get more life than that from them.

Yeah, I was about to pull the trigger on a Safari rack a few months ago but finances stopped me. When I can afford it, Im set on getting their rack. And yeah I have the roller pretty tight, but without it being that tight the knock on the driver side is absurd. But I know its not the proper way of doing things. I just need a new rack

The belt and pump should be fine, but if you didn't replace the idler/tensioner bearings, they may be making noise. If you did, you should be fine there

The work was done by a shop before I purchased the 4runner from previous owner. But I have the service records and yeah it says they replaced idler and tensioner pulleys along with water pump and timing belt. But its actually been 50k miles since then, not 40k. Dont know what I was thinking when I said 40k. Still I would think theyre fine. Isnt the interval 60k for the timing belt? Ive seen both 60 and 90, but I think 90 is for 4th gen models?

They changed the interval to 90k for '99 and later. The parts are all the same, so there is no reason it would not apply to the earlier trucks, but officially I think it is still 60k. Either way, all those parts should be fine at 50k, but that doesn't mean they are. A cheapo Chinese water pump and all bets are off.

I dont know if they are oem parts or not. I actually had the cover off a few hours ago but didnt look for that. The total cost of the timing belt, water pump, and idler and tensioner pulley were $360 according to the records. Does that sound underpriced for OEM parts?

Other than a coolant leak, how would I know if the water pump is going bad? Im almost 100% positive that Im not leaking any coolant right now.

Edit: My power steering fluid on the other hand was a little low when I heard the noise and checked it yesterday. But that doesnt mean the pump is bad I know. Could just be a leaky rack.

you never solved this?

I ended up changing my steering rack as it was very sloppy and leaking. This was 8 months ago now. I havent replaced the power steering pump yet. Havent had any issues with it other than a very faint whine coming from the pump area. I suspect it may be gradually "going", but I havent needed to replace it yet

I've had several PS pumps go out and whining is usually a sign of air in the system. Bleeding the system will usually help with air bubbles stuck in the rack. On my 96 4Runner, the PS pumps are all pretty much refurbished now a-days and often I get a bad one from the parts store, and have to go through a several to find a good one that keeps good pressure. What I mean by that is they have good pressure the wheels will turn while the engine is idle. If there is bad pressure, well, the PS will not work until you get to 1.5 - 2k PRMs. Trying to pull into a parking spot with low RPM is sometimes a pain. Downshifting to 2nd gear is usually the best way around this problem until you get the pump fixed.

Something else I've learned about Racks, is they are dummy devices and get their info from the PS Pump. If a Rack is bad, say broken seals internally, the steering is always stiff. No matter how hard the pump works it won't keep the proper pressures. If you have partial good pressure like in my case, it always goes back a badly refurbished PS Pump.

There are pressure gauges that can be connected to the PS system that can tell if there is proper pressure, but most people do not go out of their way to have these tools unless you are a professional mechanic or shop.