Scraping noise comming from engine bay - PS pump?

[wild man]

I've been starting to hear a sound similar to the sound you would hear from brake pad "screechers". The low brake pad light is not illuminating. At first I though it might be the compressor wheel scraping against the housing, because I only heard it when I was going down on the accelerator. But now I am hearing it at other times, so now I am thinking it is the PS pump.

When I first bought the car, and drove it home (1 and a half hours), the PS did not work. When I then saw that there was no oil in it, I popped off the belt to save the pump from getting (further?) damaged. A few months later, I looked into the problem, and saw that the return line had a split in it, so I replaced it. But I didn't have any PS fluid, so I used 45 weight hydraulic fluid (had 5 gallons of that). It worked fine until recently, when it got real cold. It was starting to have that grrrr
noise and when I looked into the res, the fluid was all foamed up. I then drained the hydraulic fluid out, which I though might be too heavy for cold operation, and replaced it with PS fluid, thinking that would get rid of the noise and foam when cold, but it did not.

Is it likely that the pump is making the scraping noise that I am now hearing (not just when cold)? I do have a spare, but I hate doing under-the-car work in below freezing temps.

I would much prefer to simply eliminate the PS, as PS is something I don't like. I could just remove the pump and drain the oil out of the rack, but that is still not as good as having a straight-up manual rack, because the steering wheel must be moved a small amount left or right to open the valves for the fluid to start flowing, before the wheels can be moved manually. This introduces a small amount of play in the steering wheel. And the reason I prefer manual steering is because that play does not exist. And if there is one thing I really hate, it is play in the steering wheel (even with the PS system working properly, it is still there).

Short of changing to a manual rack, which I understand are hard to find, can the power rack be modified to get rid of the play when operated manually? I would actually prefer this over a manual rack, due to it's low ratio (fewer turns, lock-to-lock).

[Techno Duck]

The steering system takes neither hydraulic fluid (40w is just a bad idea) or power steering fluid. ATF is what your supposed to use.

There should also be no play at all in a power rack under any circumstances, with the pump running or not. Time to check your tie rods (inner and outter) and the steering shaft.

If you want to make your power rack manual, clean it out, fill it with grease and cap the line fittings off. Many do this for track cars.

[white944cup]

I agree that you should be using ATF, but are you sure that is where the noise is coming from? I would take off the PS belt to verify..... I just recently had a similar noise (like crickets chirping) that ended up being a deteriorating bearing in the idler roller for the timing belt.

[nize]

if the ps fluid is foaming, you have a leak in the system somewhere that's introducing air.

[bebbetufs]

Make sure you check your belts, a loose timing belt slipping on the water pump pulley may cause a similar sound. Also check for oil leaks from the front seals. You don't want oil to get on the timing and balance belts. It may be unlikely that this is your problem but no point in risking your engine.

[wild man]

Since the "heat wave" has hit (highs in the low 40's), the problem has gone away. No scraping noise, no groaning, no foaming. This, and the fact that Techno Duck mentioned that ATF is supposed to be used, leads me to believe that hydraulic fluid, as well as PS fluid, has too high of a viscosity for use in below freezing temperatures, for this particular hydraulic pump (I do have a spare, if it was bad, but it doesn't seem to be, now). I do happen to have a quart of ATF (the high mileage variety, to boot) lying around, so I will replace the fluid with that before it gets real cold again (I hope that doesn't happen though). But I'm curious what the viscosity of ATF actually is. Does anyone know?

I do have a slight "difference of opinion" to what TD says about the steering precision of power racks though. I do not believe that they are capable of matching the precision of properly adjusted manual rack. That IS the reason that I don't like power steering. Without some sort of modification (besides greasing it and plugging the ports) I don't think the power rack can equal a manual rack. I may be nit-picking here, but this is something that I'm a real stickler (some might say fanatical) about. To me, this is what driving a car is all about. You're not on the gas, or the brakes, ALL of the time, but you are ALWAYS steering it, if you are moving. This is the main reason that these are the cars that I drive. In this respect, the 1980 924 with manual steering was the best I ever had. With the 89 951 (with power working) and the 87 924S (with no pump attached) you can go down the road working the wheel back and forth 1/8 to 1/4 inch, or so, and the car continues in a perfectly straight line. But this was not so with the 1980 924, after adjusting the rack. Even the slightest movement of the wheel caused a (ever so slight) change in the direction that the car was going in.

I think I understand the reason for this. It has been over a decade since looking into it on the 924S, but this is what I recall. After removing the cover plate where the end of the pinion shaft is, you will see that there is a spring-loaded plate that can pivot left or right, on a center point, depending on which way the wheel is turned. This is what opens the hydraulic valve for the chosen direction. It is only after this plate gets "flipped", that the pinion is able to move the rack manually. I think to only way to get the rack to move right away manually, would be to replace the spring(s) that allow the plate to move, with something solid. But since I have not looked into it any farther since then, this is where the story ends.

[AaronM]

PS fluid needs to meet GM's Dexron ATF specifications. Other types will also cause issues, so make sure that the ATF you have laying around lists compatibility with GM's Dexron spec.

[wild man]

The high mileage ATF that I have is "super tech", which I believe is walmart's store brand. It says it is suitable for use in general motors and ford automatic transmissions where a dextron-III or mercon product is recommended.

Other than possibly the weight, I was under the assumption that PS and AT fluid were essentially the same as hydraulic fluid, since they are all hydraulic systems. But I think there are 3 different weights of hydraulic fluid that you can get, with the 45 weight that I was previously using being the medium weight. I'm not sure what the exact weight of the lighter and heavier fluids are, but it looks like ATF is probably the lighter weight product.

[AaronM]

ATF, while a hydraulic fluid at its core, has many additional components such as lubricants and friction modifiers that make various versions of ATF potentially incompatible. For example, the very old Type A or Type F fluids are often incompatible with newer transmissions.

I believe, but I am not sure, that Dexron III is backwards compatible with the original Dexron spec, but you'll want to check on this.

In any case, there's more to it than the fluid weight and straight hydraulic fluid will most certainly not have the proper additives for long-term operation of the pump.