That’s probably a good way forward if you can lay the truck up for a few more days as nothing beats OEM part.

My favorite method to bleed the power steering system requires a length of tube and a rubber cap/stopper. I drain the reservoir, remove the power steering fluid return line from the reservoir, cap the open port on the reservoir, and insert a length of clear tube into the power steering return line. Fill the reservoir, start the engine for only a second, refill reservoir and repeat as necessary until the fluid is new and there are no air bubbles. It’s similar to a transmission flush as you are using the pump to force new fluid through the system. Works like a charm on every vehicle I’ve ever done a pump/rack/line on. Pretty much the only way to get all the air out of the power steering system in some gm vehicles.

I used this method to flush the old fluid out but I can re-flush again if air won't leave the system using the Toyota service manual instructions. Ordered the rebuild kit on Amazon yesterday so most likely the truck will sit for 1 week. Not really a problem.

Interesting. I guess the o ring you didn’t replace was causing it to suck air in so no amount of flushing would matter

Yep, this right here. When I removed the reservoir for the 2nd time I found the o-ring binded and split so thats why I think air kept re-introduced itself.

I think the main cause to my problem was the old fluid being very old + the screen on the reservoir being completely blocked of crap. Never lost PS on my rig and always worked. The pump was suspicious because the excessive whining was instant and never went away when as before it was just in the cold morning and then went away.

@badluck You think I could flush the power steering by just using my transmission fluid exchanger and just hook a hose to the return line to the used oil. Then pump new fluid until the fluid comes clean. Then feel to the proper level?

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I can’t remember your exact fluid exchange setup for transmissions. The problem that I ran into was the power steering pump flows fluid faster than I could fill the reservoir. That’s why I changed my method to 1 second engine running intervals.

So I have the pump all torn apart ready for new seals/gaskets which are coming tomorrow (Gates 348376) and upon discovery when I was eyeing the Toyota service manual instructions on pump reassembly and looking at the inscribed marks, I actually found the rotor facing the wrong way. The service manual says to have the mark facing upward when I found it facing down. Weird but here are the pictures of it all apart.

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All fixed! Rebuilt the pump yesterday and discovered o-rings dry rotted and hard. Today I jacked up the front wheels and turned the steering wheel when it was turned off and running. Following the Toyota PSP bleed procedure and on the 2nd round, all air pockets are gone. Just now topped up the reservoir to hot line and the power steering on my truck never felt great in years!

HIGHLY recommend the Gates 348376 kit to rebuild the pump. Patience is key. I think the main cause of my problem was the reservoir screen being blocked of junk. 3 cans of brake cleaner got it clean enough.

Nicely done and congrats on getting to the bottom of your problem. Good call on sticking with your original pump and doing the rebuild.

Yup good job. Glad your gates kit worked out for you..

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I did the flush, and while it helped, I wanted to clean the reservoir as well.

I got a used power steering pump from the local Toyota specific junkyard, and then I picked up the rebuild kit. I wanted to have a backup in case I damaged something on the pump on my truck.

The junkyard one I attempted to clean with Ballistol. Didn't really help. Had to resort to brake cleaner.

The one on the truck, I ended up using about a 1/4 to 1/2 bottle of brake cleaner. I found that if you use an air nozzle and spray air in there, you don't need to flush it with as much brake cleaner.

I'd say the flush got the power steering back to 80% and the reservoir cleaning got it the rest of the way.

I flushed several times and can see through the screen, but I still have pump noise. I am wondering if this has to do with the fluid being used to replace it.

As I have noticed in the colder months, my pump is more noisy than the warmer months. So my theory is that power steering pumps prefer toyota fluid vs. aftermarket synthetic.

As I had a pump that was very noisy. Cleaned the screen and flushed the old fluid all out, and put toyota ws fluid into the steering system. This one is perfectly quiet and functions perfectly again.

So, I am wondering if the fluid has any bearing on the noise level?

As the 02 pump on my 98 Daily driver, I know it is clean and is so much quieter now in the summer.

Am I on to something? Or just incorrect at all on this fluid as synthetic fluid is a lot thinner than toyota transmission fluid and wondering if it's effecting the noise level?



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My 2000 Toyota 4Runner has around 421,000 miles and also has the original Power Steering Pump. I noticed the pump moaning around 8 or 9 months ago. It has a very slow leak. I just keep adding fluid every month or so, depending on how much I drive it. So far so good, and I have been doing this consistently since discovering it.

Swore my whine was the PS pump going bad. Drove it for 4 years that way and finally decided to fix it.

Did all the things mentioned in this thread staring with the cheapest fix first: 1. flush/change the fluid and cleaned the screen in the reservoir; 2. rebuilt PS pump using the Gates rebuild kit; 3. replaced AC idler pulley; and finally 4. purchased a remanufactured PS from RockAuto. None of the "fixes" solved the problem. Whine was still there.

Finally took advice from an old mechanic friend of mine long gone: used long screwdriver and put it on the alternator and other end to my ear and sure enough, could hear it whining and "grinding". Bearings were bad.

Installed Denso remanufactured from RockAuto and whine is gone! Changed out all 3 belts while at it. Swear truck runs better now than it has in years.

So don't rule out the alternator bearings as the issue.