How to flush power steering system?

I was driving home and heard a noise while turning steering wheel. I stopped at the gas station and my PS fluid was really low so mechanic added Trans fluid to my power steering - didnt even ask me. How bad is it, what should i do?

Thx

one or both of the ps hoses may be leaking. very common. Or the reservoir may be leaking. very common also. fix or replace the those items. check the ps pump for signs of leakage.

Here are two procedures:

Get two quarts of the best synthetic ATF from your auto parts store. I used Mobil 1.

Extract as much of the fluid from the reservoir as you can, using a turkey baster.

Optional: remove the reservoir and flush it out with gasoline. I did this, since the filter inside is not removable.

Remove the return hose from the reservoir. It’s the forward hose, coming from the radiator, and into the bottom center of the reservoir. Have something ready to plug the reservoir pipe, and catch any residual fluid in the reservoir. I used a rubber cap, designed to cap off vacuum lines, and a couple of shop rags. You’ll need a new hose clamp.

BTW, this center clamp allows a leak to develop. Best to replace it anyway.

Fit a length of rubber hose onto, or into, the return hose so that you can route it into a catch can of at least two quart capacity. I used a cut-off bleach bottle, since, being white, it is easier to do the next step, as well being an easy target for the stream of fluid.

Fill the reservoir with new fluid. Have both bottles of ATF open and handy. With one hand on the hose, aiming into the bucket, and the other on the bottle of ATF, have a helper start the engine. Keep pouring ATF into the reservoir until fresh fluid comes out into the bucket. Then shut off the engine, reattach the hose, and top up the reservoir.

DO NOT move the steering wheel with the return hose disconnected, and the engine running! It will pump lots more fluid, and, if the hose is not restrained, it will blow fluid all over!


Optional Dave “Roadfly” Kowached Method

Every night, after coming home from work, extract as much fluid from the reservoir as possible. Fill with fresh fluid. After running two quarts through this way, the system will be much cleaner.

Once cleaned this way, do one reservoir-full at each oil change.

the owners manual has no info on ps fluid. is prestone ps fluid OK? ATF? Other?

Originally Posted by edjack

Get two quarts of the best synthetic ATF from your auto parts store. I used Mobil 1.

I take special interest in this as you guys seem to know how to do all this stuff inherently and I just don't.

I've been scared to "flush" my power steering fluid even though I have a noise upon cold engine startup which might be the fluid. I had asked the parts guy and he gave me power steering fluid (he said it was Dexron II) which I put in, only to find out belatedly it's Dexron III ATF you need, and even then, they don't make it anymore so you really need Dexron VI ATF!

My question is ... is Dexron VI ATF the same as "get two quarts of the best synthetic ATF from your auto parts store" ???

Yes. ^^^
Any Dexron III ATF or higher.

THere's another way to do a complete p/s flush w/out even having to turn on the engine. I've done this on several of my Toyos & Lexus autos and imo works better than relying on engine (pump) assist, because you get to control very precisely how much fluid flows out of the system.

PROCEDURE:
Raise the front wheel off ground so you can turn the steering wheel l-r w/out the tires dragging the ground. Then, using a turkey baster or some suction pump, suction out as much old, nasty looking fluid out the reservoir as you can. Then remove the return hose (hose going to radiator) from the reservoir. Expect some fluid to remain inside the reservoir, so have a handfull of used towels beneath to catch/absorb the spill.

Cap off the nipple at the reservoir, because you will be refilling the reservoir w/ fresh fluid, and you want this outlet closed. YOu can use another hose w/ a bolt plugging the end up, or a long length hose w/ its end raised higher up than the opening of the reservoir, or a cap that you found to fit the nippple, any means at your disposal to ensure that this nipple's closed off and not leak will do.

THe hose that's separated from the reservoir canister will spew out the old fluid, so place a catch can (or quart milk jug, 2 liter coke bottle, etc...) over this hose. Now you're set. fill the reservoir all the way to the top. W/out cranking the engine, turn the steering wheel left, then right, then left and as you do so, you'll see the fluid pump out. Maintain steering until fresh clean fluid either comes out the hose or you reach empty on the reservoir, and in this case, refill and repeat. The trick here is not to run the reservoir bone dry, as this will introduce air into the hydraulics. when you're done, reinstall hose, lower car, and clean up.

PS Bluebee:
I buy D4 ATF by the 5 gal buckets as I believe Redline ATF is THE BEST of the best. Redline starts w/ very high quality synthetic base stock, therefore they don't rely on too much improvers to prop up viscosity at 100c temps. Thus their line of synthetics outlasts its competitors even because of how stable their fluids are. But it's rarely, if ever, the heat that kills P/S systems, as p/s systems NEVER reaches 100 deg C for street use. It's contaminants from the pump's gears (as it wears out) and airborn dirt collected under the cap that's gotten past the filter and allowed to cycle repeatedly, chewing out the hydraulic's seals. THe trick is to flush often, and to replace the reservoir b/c the (marginally effective) filter that's in there is non replaceable. Perform the flush every 25k miles, or 2 yrs, and replace the reservoir every 50k miles and or 4-5 yrs and you should never have to replace your p/s rack and/or pump due to premature failure. Now leaky hoses and torn dust boots, well, that's another matter...

Originally Posted by Jason5driver

Any Dexron III ATF or higher.

This is the right answer, but, in the auto parts stores I visited (Kragen and Autozone), there is nothing labeled Dexron III!

When I asked, the counterperson said Dexron VI is what you need nowadays; of course, that's the same counter-type-person who sold me the Dexron II PSF instead of the ATF!

So, it would be nice if folks chimed in whether or not there is such as thing (on the shelves) as Dexron III nowadays (they told me GM no longer certifies Dexron III so it would be years old if it were).

Originally Posted by bluebee

This is the right answer, but, in the auto parts stores I visited (Kragen and Autozone), there is nothing labeled Dexron III!

Turns out Dexron III is no longer made; use Dexron VI instead.

Lots of noisy engine information in this cold-start squeal thread.
Leaky power steering information in this thread.
Cloudy power steering fluid in this thread.
More noisy power steering threads here.
Fixing the leaky power steering reservoir cap here and here.

Originally Posted by bluebee

these images are the reason i love your threads!

Originally Posted by ganesht

these images are the reason i love your threads!

Just to update this thread, we have new advice for the users:

• Every oil change, suction out about 8 ounces (250 ml) of the power steering fluid and replace with Dexron VI ATF
• Every five years (or so), when you replace the two lower oil-filter stem o-rings, also replace the o-ring in the power steering fluid reservoir cap
• Likewise, every five years (or so), remove the T20 Torx bolt holding down the circular screen filter in the bottom of the power steering fluid reservoir and flush with gasoline (off the vehicle!) to clean the screen

See also these threads from the VERY best of E39 Links

- How to clean the power steering fluid reservoir internal filter (1) & how to replace the cap o-ring (1) (2) & why you want to fix the power steering hose drip onto the alternator (1) (2) (3) & how to debug PSP power steering pump noises (1) (2) (3) or steering rack noises (1) & a nice power steering pump autopsy photo (1) & how to flush fix cloudy ATF fluid (1) (2) and what PS fluid to use (1) (2) & DIYs to replace the power steering hoses (1) (2) (3) (4) (5).

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From the sounds of it, OP doesn't need a flush. He thought the mechanic put ATF in there by mistake, that's why he's asking about a flush.

When I bought mine, previous owner had PSF in there. I changed it out, but used a diff sucker at work. Same principle as above, just made it much easier.

For the third time, I sucked out all the fluid from the reservoir and replaced it; but, this quick-and-easy-fix attempt failed to eliminate the cold-start squeal ... so I think new belts and perhaps roller-thingies are in my future ...