Been having an onoing saga with Superblue's ('94 4.0, 110K miles) PS system over the past couple of weeks or so. As a preface, I have for a long time been needing to top up about once a month or two the fluid reservoir, usually by not a substantial amount. Then recently I was in WM and noticed a product by Lucas (reliable co., except for electrics, right?) that is their stop leak addititive for the PS system. It basically is very viscous and reminds me of the crankcase product called Motor Honey. What really caught my eye was their money back guaratee if the stuff did not take care of your leak. Possibly I found a way to stop that irritating, slow chronic leak once and for all? I bought a bottle and squeezed it into the reservoir, as idrectled. The first day or so everything seemed great and very smooth, PS wise. The next a.m. though, I noticed when I started the car up I had no power assist at all. Driving the car a few yards and pulling HARD on the wheel in either direction eventually resulted in the system suddenly "popping" back into place, like it normally operates. The system would then seem to vary, with long spells of sitting (typically overnight) sometimes resulting in the same scenario, yet at other times, no. However, generally there was this feel and even sound (e.g. gentle moaning) that the system had air in it. I had tried the usual bleeding method of putting the wheel to either extreme for a few seconds while in park/idling, but this action did not seem to bleed off the air. During this time though the fluid in the reservoir was at correct level and the fluid appeared like it should, whenever I checked it. Still, I was convinced that maybe b/c my problems started after the use of the Lucas product, maybe if I bastered the fluid out of my reservoir and replaced it with regular fluid (or trans. fluid) my system might return to normal.

Fast forward to today when, after a rather "airy" day (but no stiff a.m. steering episode) I decided to go with the "fluid" transfer using my baster, as mentioned earlier. Howeer, when I opened the reservoir cap I was stunned to see there was very little fluid in it. This development would seem to indicate that in fact I have a substantial leak (now?) in the system. I searched around under the reservoir and even under either arm of the rack (e.g. the rubber belows), but saw no signs of a leak onto the other parts of the car or onto the pavement. I got out my regular fluid (well, I decided to start with generic transmission fluid - Dexron V or some such, in case I lose it) and topped up the reservoir. I started her up and let her idle for a bit, revving the engine up a bit from time to time. I then tried moving her steering wheel from side to side while in park, which resulted in major groaning noises and a disturbing feel to the wheel. I shut her off, then checked the same spots again for signs of a leak (none, again), but this time when I went to open the cap I was totally taken aback by the “pink milkshake” in front of me. The fluid looked like someone had put it in a blender and whipped the it into a foamy froth. The level also appeared to be a little higher than before, but I attribute this to the fact that it had been frothed up. What in the world is going on with my PS system? How is air apparently being pumped (sucked?) into it like that??? Should I be raising hell with the Lucas Co.? I had none of these problems until right after I put in their additive.

A few days ago I had a retired tech bud of mine take a lot at the system from above, while working on something else for me in the engine bay area. His opinion off the bat was that I needed to change out the two hoses leading to and from the reservoir (e.g. to the pump and back from the fluid cooler), as they were both very heat and time-hardened. He suspects that one of them has developed a slight fluid leak b/c of this condition, meaning that the metal connectors attached to same are no longer firmly clamping the hose(s) to their respective connector fittings. If so, that would seem to explain the source of my original slow fluid leak. I'm wondering now if, even more loose, that situation could result in air being pumped/pulled into the system from the outside while operating.

 

Never ever ever use those 'seal expanding' leak sealers except in emergencies - they are not a permanent solution, they will result in damage and poor function sooner or later because they swell the existing seals, they never stop swelling the seals, you don't really say how long this stuff was in your system aka what is recently. The fix is misleading because it will for sure stop your leak but it will eventually mess up your system totally, these remedies in a can should be banned or forced to make clear that they are not a permanent solution you may now have piston seals binding in the rack.

If those hoses give out trust me there will be no doubt - especially the high pressure one, the fluid cooler will be soaked as will the subframe, air can only get in if it is being drawn in (unless your fluid is crazy low) so that would be the return lines / cooler connections if anything, additional viscosity will make that worse, auto trans fluid should not froth readily either .

What do you define as your 'regular' fluid since you refer then to Dexron - not sure what your pump is spec'd for but if ATF isn't specified for it that's a bad idea.

 

Some of your symptoms remind me of an issue I had with my 5.3 with the original Saginaw type pump. The line to the rack unscrews and reveals a metal mesh filter element behind it. Mine was very clogged with metal debris that led to inconsistent performance and groaning sounds similar to what you describe.

I’m not familiar with the 4.0 pump but it looks like it has a similar fitting from the quick search I did.

 

My 2003 XK8 Coupe indicates using Dextron 3. Hard to locate Dex 3 now but the new Syn Dex6 is backward compatible with Dex 3. Usually store brands are $10-12 a qt. Since you plan to repair leak and not drive much, maybe no harm (I doubt it) to just use the Dex 6 unless you can locate cheaper Dex3. Once repaired, you can flush the system and have new synth. fluid