bertjnovak

1991 ls-400 POWER STEERING NOISE and foam in reservoir.

Possible cause: Power steering pressure hoses break down over time and flake off neopreme that collects at a screen in the power steering reservoir. When this screen get clogged air can enter the system past an "o" ring that hardens where the reservior connects to the pump. A clue is power steering fluid around the top of the pump body around where the reservoir attaches. If fluid is leaking around the drive shaft, replace the pump or have it re-built before fluid gets into the altenator and destroys it.

The good news is that the "o" ring is inexpensive and the resevior is easly flushed.
The bad news is the power steering pump must be removed to remove the reservoir.
The power steering pressure hose and two short return hoses should also be replaced and the system flushed with new fluid.
The labor hours to do this repair is nearly the same as replacing the pump with a new one.

Ps: I think it is possible to loosen the pump and moving it forward and removing the reservoir but I have not done it.