Milky hydraulic fluid

Power steering assistance is generated by the power steering pump. This is accomplished by pressurizing hydraulic fluid and applying it to the steering gear; any failure that compromises this process can result in increased steering effort (a stiff steering wheel). The first item to check is the serpentine belt; if inadequate belt tension is present or the belt is missing, the power steering pump pulley will not be rotated fast enough to allow the pump to work. The second item to check is the power steering fluid reservoir; if the fluid level is too low (caused by a leak), air will be introduced into the hydraulic circuit and the hydraulic fluid will not be properly pressurized. This may also result in aerated fluid which appears foamy in consistency. The last item to check is the fluid condition itself; if shining a flashlight on the fluid reveals a glitter-like appearance, chances are that the internal parts of the pump are worn and are not longer capable of generating pressure. In this case the power steering pump would need to be replaced along with a whole system flush. In some severe cases with excessive debris, other components within the steering system may need to be replaced as well. You can read more here: https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-power-steering-pump

Causes of Power Steering to fail.

• Contamination problems occur more frequently in rack and pinion power steering systems. Contamination can occur when pumps fail, hoses deteriorate, or moisture gets into the power steering fluid. All of these problems result in material contaminating the power steering fluid which can plug small orifices in the steering system, increase friction, and interfere with the fluids hydraulic characteristics, resulting in a failure of the power steering system.

Low fluid

• Low power steering fluid levels reduce the amount of hydraulic pressure created by the power steering pump, resulting in hard steering. Low fluid levels also cause increased wear of the power steering pump from inadequate lubrication and high fluid temperatures which further accelerates pump wear. Low power steering fluid can cause a power steering pump to wear out prematurely and can result in the eventual failure of the power steering system if not corrected.

Snapped belt

• Many vehicles use power steering pumps which are driven by a belt connected to the crankshaft of the engine. Worn belts can slip causing a reduction in the fluid pressure produced by the power steering pump, which increases the effort needed to operate the steering system. Power steering belts that catastrophically cause an immediate loss of power steering as the pump is no longer being driven by the engine.

Worn pump

• As power steering pumps are operated and age they wear out. The seals and internal parts of the power steering pump break down over time and lead to an incremental loss of fluid pressure. As the pump wears out, pump noise and steering effort increases. Worn out pumps will eventually fail, leading to a total loss of fluid pressure and a failure of the power steering system.

Leaks

• Power steering systems require hydraulic fluid to operate. Hydraulic power steering fluid can leak from worn or damaged hoses and failing seals. When enough fluid is lost, the power steering pump can overheat or wear out prematurely, resulting in a loss of hydraulic pressure and failure of the power steering system.

what vehicle? are you talking hydraulics or engine oil? milky usually means moisture in the fluid. high pressure, some venting is clogged

The "milky foam look" is a CLASSIC sign that there is water (or maybe antifreeze) mixed in with something that has a petroleum base ... such a oil or hydraulic fluid!

Oil or fluid will look milky if it is either emulsified (with water) or if it become aerated.

Emulsified fluid or oil will promote corrosion and aerated fluid is compressible which is unsuitable for hydraulic applications.

Time to change the power steering fluid. Some cars use power steering fluid, while other cars use transmission fluid. Do not use the wrong fluid in your car or you will have even bigger problems.

replace power steering fluid with new fluid bleed system sound like you have air trapped in the system.replace fluid and bleed system see what happens.

The power steering is a sealed system. No way coolant could get in there. It might be contaminated by moisture from the air though. So you could suction it out (a turkey baster works great), and replace with clean fluid.
Wasw the engine overheating from low coolant level? Hopefully, thats all it was. Keep it full!

Probably not. There is enough trouble with foaming and cavitation in the power steering pumps when the CORRECT fluid is used. Why would you even ask? Power steering fluid is NOT that expensive - go buy some.

change hydraulic filter again and probibly the oil use ahigh quality hydraulic oil like Case-ih hytran fluid this oil has a high moisture retention factor be sure to drain all the cavitys 5 plugs total and let them drain completely before refilling