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Fix for infamous PS pump noise?


April 3, 2001
Reaction score
City, State
Bakersfield, California
Year, Model & Trim Level
91 XLT 4dr
Hi guys,

A friend of mine (who owns a Taur*s, poor guy...) says that his mechanic friend at the Ford dealership told him that the fix for the infamous noisy Ford power steering pump is to add Ford friction modifier, that is made for the limited-slip diff, into the PS fluid. Have any of you heard about this and/or tried it?

I am on the 3rd pump in my '91 (160k) and my Aerostar (145k) has its 3rd pump in it. All have suffered from the whining noise. They've never cleared up the noise even when freshly rebuilt, broken-in, properly bled of air, etc. I'm tired of it and am wondering if any of you have had any luck with your rebuilt PS pumps. The pump itself is an inherently noisy design. Thanks Ford... you guys didn't do your homework (again).

Thanks ! ! !

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Every Ford I have ever owned has had a noisey pump....From 67 thru 94...I have never heard of adding limited slip to it..I really think that would make it worse as it would make the fluid thick, therefor making it harder to pump...Can't say for sure..

Try ATF fluid.

Ford power steering pumps since the 80's can use either power steering pump fluid, or ATF fluid.

Only don't mix them.

Use ATF fluid, from what I remember power steering fluid doesnt contain the stuff recommended by Ford for that style pump. It is kind of funny cause when you read the back of the container it says it will work with all vehicles. But most importantly make sure that you bleed bleed bleed that system before you start the engine with the new pump, when you think you are done bleeding it out, bleed it out some more. It took me 3 hours to bleed the system on my 92 but it doesnt whine anymore, like others I suffered from the whining pump problem the first time I changed it. From what I was told the TRW pumps that were used on the early explorers, rangers and aerostars are POSs. They say that if any air is in the pump when you first start the engine that it will whine for life. Just my .02 on what worked for me.

How do you bleed the PS pump??

Chiltons would have us disconnect the coil and crank the engine while turning the wheel, I don't like that cause it is a little hard on the starter.

The procedure I use is to jack the front end up until both wheels are off the ground. (Make sure your equipment can handle this, I would recommend a sturdy floor jack and jack stands) With the fan belt removed and the pump reservoir filled with fluid rotate the pulley by hand while a partner turns the steering wheel from left to right (but not full lock to lock)(You can also turn the wheel yourself by grabbing the steering shaft but it's harder to do) while you are doing this you will notice large bubbles of air rise to the surface of the fluid and the fluid level will drop as the air comes up, add fluid as needed. Basically keep doing this till air bubbles stop coming up and then keep doing it for a while. I know that it's a pain in the A$$ but so far my 3rd pump has been nice and quiet. I have heard of some people using a vacuum pump to remove air from the system as well.

kinda off topic, but my power steering fluid is leaking. i cant tell exactly where its leaking from. i was looking yesterday and it seems its either from the hose comming from the pump or where the 2 metal lines connect to the unit it self. i'm not really sure how bad it is, but i'd like to fix it =/ if anyone has had any expirence with this, let me know what to do

Jeff aka Lamah

There is a special fitting they use to attach the pressure line to the pump, you will notice that the line moves freely at the point where it is attached to the pump. I think that there is some sort of Teflon seal that goes in this joint to prevent it from leaking but still allowing it to move. This would be my first guess, anything else is probably a loose or bad hose. Good Luck.


Tim - Thanks for your replies! I've tried the crank-the-engine method, with front wheels off the ground, with limited to no success. I can never get all the air out. Yes it's hard on the starter also to do that. That is a REALLY good idea to remove the belt and rotate the pump by hand.

The rebuilt pump came with instructions to vacuum-bleed it using a rubber stopper to go in the fluid fill, copper/steel tubing, a tee, etc. and a source of vacuum. I might try this first before switching to ATF. How would you ever be able to purge all the PS fluid out when switching to ATF?

In my experience, the easiest way to find your PS leak is to drive your truck to the car wash and pressure-wash the pump, steering gear, frame, etc., everything in that area. Try not to get water on your exhaust manifolds. Dry off the PS hoses, pump, and steering gear with a towel as best you can, then start it up and watch the hose ends to see where the leak comes from. Sometimes it helps to gently turn the wheel while watching the hose ends. This causes the system to build more pressure and may force the leak to appear suddenly. Or you can go get some of that PS leak stopper stuff.

I think I got that bleeding procedure from the Ford service manual. I purged the system on my 92 with a couple of quarts of cheap ATF. I pulled the return line off the bottom of the reservoir and plugged the hole with the cap that came on the new pump, I then routed the return line into my used oil can. Since I was putting another pump on I didn't really care if it ran dry. After starting the engine I just dumped the 2 quarts of cheap ATF through into the PS pump while turning the wheel. This is a pretty crude method of purging the system and I wouldn't recommend it if you intend to reuse the pump. Hopefully someone will post a better procedure for doing this. If and when I get home I'll see if I can find the brand and type of ATF that I used. I know there are several different types and I don't think I used the same type that is recommended for the explorers auto trans.


When you buy the ATF look for a type F fluid that meets Ford Specification M2C33-F, this is what the manual is calling for and even though power steering fluid cans say they meet most ford specs they dont seem to work too well with the early model pumps.

Tim - Thanks for the info. Where did you find that Ford spec number for the ATF? As you know type F is the old school Ford fluid, like I used to put in my Mustang.

Based on my experience thus far with these rebuilt pumps, I really think that sometimes when they rebuild these pumps they just clean it up a little, slap on some black paint, and ship it, with no attention to the internals. Maybe that's just the paranoiac in me...


That Spec number came out an old service manual for the early Explorer, Ranger and Aerostar. I bought the quiet pump from Autozone, it is remanufactured by a company called ATSCO. They seemed to do a really good job of it and they didn't use any paint. They also serial number all of their pumps and from what I read in the paper work they seem like they would be a pretty good company to deal with, maybe others on the board have had experiences with them that they could share. I got the loud pump from Kragen Autoparts and it was one of the "black paint" specials, I don't know if it was crap but I do know that I didn't bleed it very well and it was just as loud as the one it replaced. I'm not really sure what you are looking for in terms of quiet, most early explorers make pronounced hissing noises from their steering systems however they shouldn't make that loud nasty whining sound that seems to cut through even the loudest stereo.

The Ford Noise

Every Ford anyone I have ever known whines. My Mustang did it, My moms old Tarus, my buddies old Aerostar. Just consider it a Ford trademark. Anyhow powersteering pumps are cheap.

Ummm... Actually they're not that cheap; they're like $80 here in the central PRC (People's Republic of California). And the cost of the pump is not the problem - it's the bloody hassle of changing the pump, getting fluid everywhere, messing with the hose ends, bleeding it, adjusting the belt, cleaning spilled fluid off everything including your garage floor, etc. No thanks.

I dunno, I replaced my steering gear once and I didnt have such a problem, wasnt too difficult. Never attempted a power steering pump.

Wow, you resurrected a 4 year old thread. :p

Use full synthetic PS fluid and it will significantly reduce the noise.

urbanistic said:
I dunno, I replaced my steering gear once and I didnt have such a problem, wasnt too difficult. Never attempted a power steering pump.


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