Why is my power steering reservoir loosing fluid, what would cause the fluid to be "foamy" on top, and what should I use to fill it with?

MS5931 IS THE ONLY FLUID THAT CAN BE USED FOR THE POWER STEERING SYSTEM. NO EXCEPTIONS!

Important note: The factory fill power steering fluid for all 1999-2004 Grand Cherokees is a unique fluid, MS5931. ATF+4 (MS9602) should not be mixed or used as a “topping off” fluid on the Grand Cherokee WJ. All WJ models should be serviced using ONLY the special MS5931 fluid. ATF+4 is NOT an approved Power Steering Fluid and should never be used under any circumstances. Note that all fluids will darken in color with usage and fluid color is no longer an indication of fluid condition.
The 'foaming' you describe is almost certainly air getting into the system. The power steering pump will cause a suction effect in the pump and then pressurize the system. Look for loose hose clips, damaged piping, and leaking seals on the pump body between the pump and its fluid reservoir

If the pump went dry there is a chance that it was damaged....replace the line, re-fill with the proper power steering fluid to the full mark, cap it, start the car and turn the wheel all the way right, then left a few times to help fill the rack with fluid. check the level and top it off as necessary. drive the car a few miles and re-check the level. Whining after the reservoir is full indicates damage to the pump, steering rack or both.
Good luck

Make sure there are no leaks in the return hose. If there are leaks in the return line it could be pulling in air and causing the foaming and noise. If there are no leaks you fill the reservoir with power steering fluid and crank the car then turn the steering wheel all the way to the right then all the way to the left a couple of times and that should get rid of all the air in the lines.

If its foamy than its cavitation. Let it sit overnight and see if it fluid is full in the reservoir. If it is than I would try flushing the power steering fluid. If its low top it off and check for leaks

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

First thing you need to do is remove thwe return line from your power steering reservoir. Thats the thing you put the power steering fluid in. Run that hose to a large container where you can catch a lot of fluid in. Now you want to make sure you have your new power steering fluid on hand before you start and another person would be very helpful also. Have your helper start the car and turn the wheel back and forth while you pour power steering fluid in the reservoir. Do not let your power steering fluid run completely out you can ruin your pump and or steering box. Continue to pour in new steering fluid until the fluid coming out of the hose thats in the bucket is clean fluid. Turn vehicle off reconect the hose to the reservoir and top off. With the lid off reservoir start the vehicle back up and turn wheel all the way back and forth many times(do not turn it to its furthest position where it bumps) continue to make sure the fluid level is always full. By turning the wheel back and forth you are bleeding the lines to get all the air out. Do that a few times, refill and put the cap back on. You just changed your power steering fluid. I f your vehicle is old you may want to get new rubber hoses for your power steering system. hoses degrade over time and eventually they start to flake off into your fluid which can damage parts. Always a good idea to replace hoses especially if they are soft.

Did you replace any parts?. any way fill reservoir instal cap, start engine and turn steering whell from lock to lock, left and rigth until it stops, do it couple off times then recheck reservoir refill and repeat this until it does not need to add any more fluid, then let car idle until fluid is clear of air,(foamy) fill reservoir to max line by now noise must be gone.
Good luck

It will bleed it self.

Your problem could be a pressure side hose that has a rupture that only leaks in extreme conditions. Inspect to replace with new to repair problem. First make sure you have removed the pump caps off of the hose fittings. If ok, it appears you may have a stuck valve in the rack assembly. Replacing the rack should solve your problem. ------- The new pump should be self-bleeding by turning the wheels left and right. Let sit over night to release air bubbles, recheck fluid level.------ Check the tension of the drive belts on the pump, as they may be loose. The power steering pump and reservoir is located on the front of the engine driven by one of the fan belts. There is a removable cap on the top with a dipstick attached. With the engine off, fill this up to the full mark with power steering fluid. Replace the cap, start the engine and check for leaks. On the back of the pump are two hoses either one could be leaking. REPAIR PROCEDURE:
1. Wipe the power steering cap and area free of dirt. Remove the power steering cap.

2. Use a siphon pump to remove as much fluid as possible from the power steering fluid reservoir.

3. With a helper in the vehicle, raise the vehicle on an appropriate hoist.

WARNING :POWER STEERING FLUID, ENGINE PARTS, AND THE EXHAUST SYSTEM MAY BE EXTREMELY HOT IF THE ENGINE HAS BEEN RUNNING. DO NOT START ENGINE WITH ANY LOOSE OR DISCONNECTED HOSES. DO NOT ALLOW HOSES OR POWER STEERING FLUID TO TOUCH HOT EXHAUST MANI FOLD OR CATALYST. 4. Locate the power steering cooler attached to the crossmember support plate. Slide back the clamp and disconnect one of the two power steering return hoses at the power steering oil cooler and drain fluid in an appropriate container.
5. Have the helper turn the steering wheel back and forth quickly several times to force as much fluid as possible from the steering gear.
6. Reconnect the hose at the oil cooler using the original clamp.
7. Lower vehicle so the vehicle tires are not contacting the ground. 9. For proper fluid fill and bleeding air from the power steering system:

a. Fill the power steering reservoir to the top of the fill range using Mopar power steering fluid (ATF+4) p/n 05013458AA.

b. With the engine OFF and the vehicles tires off the ground, slowly turn the steering wheel back and forth (lock to lock) slowly 20 times to force fluid into the steering gear.

c. Fill the power steering reservoir to the top of the fill range.

d. Start engine and let run for a few seconds, then turn oft engine.

e. Check fluid level and add if necessary.

f. Start engine, and slowly turn the steering wheel lightly contacting the left and right stops.

g. Stop the engine and check fluid level. Add fluid if necessary.

h. Lower vehicle, start engine and slowly turn steering wheel lock-to-lock.

I. Stop engine and check fluid level. Add fluid if necessary.

j. If fluid is extremely foamy, allow vehicle to stabilize a few minutes, then repeat steps "i" and "j" until the fluid level remains constant after running the engine and turning the steering wheel from lock to lock.

10. Inform the vehicle owner/operator that a steering vibration may be noted for a few hundred miles until the air is completely removed from the steering system. This will help. Thanks please keep updated.please do rate the solution positively .thank you for using fixya

FIRST OF ALL YOU HAVE TO REMOVE POWER STEERING FLUID.USING A SUCTION GUN OR LARGE SYRINGE.REMOVE MUCH FLUID AS POSSIBLE.WHEN DONE REMOVING POWER STEERING FLUID.YOU NEED A INLINE WRENCH AND OPEN BOX END WRENCH TO REMOVE THE POWER STEERING HOSE.YOU HAVE TO REMOVE POWER STEERING LINE FROM THE RACK.UNDER THE CAR SAFELY RAISE AND SUPPORT VECHICLE. THEN REMOVE THE TIRE OR WHEEL.THEN REMOVE THE INNER FENDER SPLASH SHIELD.ITS GOING TO BE A TIGHT FIT AND HARD PLACE TO GET YOUR HAND TO REMOVE THE POWER STEERING LINE FROM BOTTOM.WHEN DONE.MAKE SURE NEW POWER STEERING HOSE OR LINE HAS NEW O RINGS.WHEN INSTALLING THE THE NEW STEERING HOSE.WHEN ALL IS DONE BLEED POWER STEERING SYSTEM. FILL UP POWER STEERING PUMP TO CORRECT FLUID LEVEL.THEN LET IT SET FOR 2 MINUTES UNDISTURBED.THEN START THE ENGINE RUN IT FOR 2 TO 3 SECONDS.ONLY CHECK THE RESERVOIR AND ADD MORE FLUID AS NECESSARY.REPEAT THE OPERATION UNTIL THE FLUID LEVEL REMAIN CONSTANT.NOW RAISE FRONT OF THE CAR UNTIL THE WHEELS CLEAR THE GROUND START THE ENGINE AND INCREASE THE SPEED TO ABOUT 1500 RPM.NOW TURN THE STEERING WHEEL GENTLY FROM STOP TO STOP CHECK THE FLUID LEVEL.LOWER THE VECHICLE TO THE GROUND WITH ENGINE STILL RUNNING MOVE THE CAR FORWARD SUFFICIENTY TO OBTAIN FULL RIGHT LOCK FOLLOWED BY FULL LEFT LOCK BUT DONT HOLD THE SREERING WHEEL FIRMLY AGAINST THE STOPS.RECHECK THE FLUID LEVEL IF THE FLUID IN THE RESERVOIR IS EXTREMELY FOAMY ALLOW THE CAR TO STAND FOR A FEW MINUTES.WITH ENGINE OFF.WHEN JOB IS FINISH. WARNING DONT DRIVE CAR ON ROAD IF YOUR FLUID STILL FOAMY OR POWER STEERING PUMP MAKE NOISES.REBLEED THE SYSTEM AND CHECK FLUID LEVEL AND CHECK FOR LEAKS.DONT DRIVE CAR UNTIL YOU START FEELING NORMAL STEERING.IF YOU HAVE TROUBLE DONT DRIVE.HAVE IT TOWED TO THE NEAREST GARAGE.

Get someone to help you with this. If you start the car with the reservoir half full and slowly turn the steering from left to right lock and back 4 or 5 times it should expel all the air from the system.
Get you helper to add fluid to the reservoir as needed during this process to keep it at least half full.
Top up to correct level when all air is out.