How to tell if power steering oil is leaking on alternator 1991 ls400?

First put something like paper down under the area of the leak. You will also need to see what type of oil it is.....black-oil; red-transmission fluid or power steering fluid; clear-power steering fluid; green/yellow-cooling fluid.....etc.

check your fluids oil. power steering tranny fluid brake fluid and see which one is low

The main purpose on an alternator is to recharge current back to the battery. One of the most common problems with the Lexus LS400 and SC400 is that power steering pump seal leak. Right below the power steering pump is the alternator. The power steering fluid will drip down and cause many electrical problems for the alternator. Therefore, its very common to have the alternator go bad along with the power steering pump, just be sure to check.

YOU HAVE A RUPTURE PRESSURE LINE IF YOU HAVE NO POWER STEERING FLUID IN THE POWER STEERING RESERVOIR.LOCATE LEAK THEN BLEED POWER STEERING SYSTEM BY ADDING POWER STEERING TO RESERVOIR.DONT OVER FILL BY FULL COLD MARK ON POWER STEERING DIP STICK.ADD FLUID TO RESERVOIR WAIT A 2 MINUTES.CHECK FLUID LEVEL AGAIN.WHEN POWER STEERING FLUID LEVEL STOP DROPPING.START ENGINE LET IT RUN FOR 10 SECONDS.THEN TURN OFF ENGINE CHECK POWER STEERING FLUID ADD FLUID IF FLUID LEVEL DROPS. WHEN FLUID LEVEL STOP DROPPING.SAFELY RAISE SUPPORT VECHICLE FRONT WHEELS.START ENGINE.NOW TURN STEERING WHEEL GENTLY FROM STOP TO STOP MEANING LEFT TO RIGHT DONT HOLD IN POSITION.LET THE STOP TO STOP BE QUICK.CHECK POWER STEERING FLUID AFTER YOU HAVE TURN STEERING WHEEL ABOUT 7 STOP TO STOP.WHEN FLUID LEVEL STOP DROPPING YOU AT HOT MARK ON DIP STICK BLEEDING PROCESS COMPLETE.TURN OFF ENGINE LOWER VECHICLE BACK TO GROUND WAIT ABOUT 5 MINUTES CHECK YOUR FLUID LEVEL.IF FLUID LOOKS LIKE A TAN COLOR.YOUR POWER STEERING SYSTEM FULL OF AIR.TURN OFF VECHICLE LET VECHICLE SET A LONG WHILE TO AIR BUBBLES SETTLE DOWN LOOK FOR LEAKS AROUND POWER STEERING PUMP FRONT SEAL AND CHECK FOR LEAKS AROUND POWER STEERING LINES.

Well it is either a power steering hose, the pump itself, or the power steering gearbox leaking.

hoses would be the first thing to look at. Fill it with fluid then with the engine running,. have someone turn the wheel back and forth while you look under the hood. You will see something leaking out if it is that bad of a leak.

Most power steering pumps are driven by the serpentine belt and should be in plain view when the hood is open.The following shows how to remove and replace the power steering pump and might give you a clue if not in plain sight. My dad's 1998 Ford Taurus has it nearly on top, but they could have changed things in the mean time: Power Steering Pump Removal & Installation Power Steering Pump (2V) To Remove:

1. Before servicing the vehicle refer to the precautions at the beginning of this section.
2. Disconnect the battery ground cable.
3. Remove the accessory drive belt.
4. Remove the alternator.
5. Drain and remove the radiator coolant recovery reservoir.
6. Position a drain pan under the power steering pump underneath the vehicle. Disconnect the hydraulic pressure and return lines and allow to drain.
7. Remove the idler pulley from the power steering pump support.
8. Remove the belt tensioner.
9. Remove the bracket mounting bolt located under the belt tensioner mounting.
10. Remove two retaining nuts from the bracket mounting studs. Remove both mounting studs, and pull off the power steering pump support with the pump attached.
11. Clamp the pump support bracket in a suitable vise.
12. Remove the power steering pump pulley from the pump shaft using Pump Pulley Remover T69L-10300-B, or equivalent. Remove the three bolts retaining the power steering pump to the power steering pump support and remove the power steering pump.

To Install:
NOTE: The pulley must be installed within 0.010 in (0.25 mm) flush with the power steering pump shaft.
Power steering pump special tools

1. Install the power steering pump to the power steering pump support. Tighten the mounting bolts to 18 ft-lb. (25 Nm).
2. Install the power steering pump pulley using Steering Pump Pulley Replacer T65P-3A733-C, or equivalent; the pulley face must be flush within 0.010 inch (0.25mm) of the pump shaft.
3. Install the power steering pump/pump support and torque nuts/bolt to 24 ft. lbs. (33 Nm).
4. Install the bracket mounting bolt located under the belt tensioner mounting.
5. Install the belt tensioner.
6. Install the idler pulley to the power steering pump support.
7. Connect the hydraulic pressure and return lines.
8. Install the radiator coolant recovery reservoir.
9. Install the alternator.
10. Install the accessory drive belt.
11. Fill the power steering reservoir with power steering fluid.
12. Connect the battery ground cable.
13. Run the engine and check for leaks and proper operation. Bleed the power steering system if needed.

Power Steering Pump (4V) and SHO To Remove:

1. Before servicing the vehicle refer to the precautions at the beginning of this section.
2. Disconnect the battery ground cable.
3. Remove the accessory drive belt.
4. Drain and remove the radiator coolant recovery reservoir.
5. Position a drain pan under the power steering pump. Disconnect the power steering pump reservoir hose and allow it to drain.
6. Using Pulley Remover T69L-10300-B, or equivalent, remove the pulley from the power steering pump shaft.
7. Disconnect the pressure hose from the power steering pump and allow it to drain.
8. Remove the power steering pump retaining bolts and the pump.

To Install:

1. Install the power steering pump and tighten the bolts 15–22 ft. lbs. (20–30 Nm).
2. Connect the pressure hose and secure the clamp.
3. Using a Steering Pump Pulley Replacer T65P-3A733-C, or equivalent, install the power steering pump pulley: the pulley face must be flush with the pump shaft or within 0.010 inch (0.25mm).
4. Connect the power steering pump reservoir hose.
5. Install the radiator coolant recovery reservoir.
6. Install the accessory drive belt.
7. Fill the power steering reservoir with power steering fluid.
8. Connect the battery ground cable.
9. Start the engine and check for leaks and proper operation. Bleed the power steering system if needed.

Check out the 2 lines that run from your power steering pump. With the engine running try moving them, and look for fluid leaking around the end of the hoses, you will probally find one of them leaking at the fitting. Of course be careful with the engine running, do not have any rags or anything in your hands around a running engine.

There is a reservoir attached to your power steering pump, which is mounted on the front of your engine. A stick gauge is attached to the reservoir cap when you remove it. Add the proper power steering oil directly into that reservoir if needed. Do not overfill, respect gauge mark.

If it's a power steering fluid leak, most probable it comes from a bad seal of your steering box pitman arm shaft. If it's the case, you can verify it, looking from under the vehicule, the bottom of your gear box will be covered of dirty oil.

However, reddish color fluid leak could also come from the cooling circuit of your automatic transmission or from the pan of your transmission. In conclusion, a visual check by under the vehicule will help to diagnose the origin.
Hope it will help.
Dan

As mentioned check ps fluid. If it wines when turning and still no power then the pump is internally bad.. If the fluid is dissapearing fast then its a hose or most likely a leaking rack& pinion assembly..

You must have a leak somewhere. The whinning noise is coming from the pump. They make that noise when they are out of fluid.

Are you seeing any puddles or oil drops on the ground under your car?

A power steering resevoir is't very large so it won't take very long or a very big leak to run it out of fluid.

There aren't that many parts to a power steering system either.

The leak would most likely becoming from a hose, a connection or from the power steering component cylinder or box.