Power Steering General Servicing GMC Cab & Chassis R2500

TROUBLE SHOOTING

Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

SERVICE

BELT TENSION (1)

IDLER ARM - ASTRO & SAFARI

Replace idler arm assembly if an up and down force of 25 ft. lbs. (110 N.m), applied at relay rod end of idler arm, produces a lash of more than 1/8" (3 mm) for a total of 1/4" (6 mm) in straight-ahead position.

PREPARATION

1. With belt tension correct, disconnect power steering pump pressure hose. Keep hose end raised to prevent fluid loss. Connect pressure hose of gauge to power steering pump fitting. Connect other hose from valve side of tester to steering gear inlet.
2. Open valve and run engine until fluid reaches normal operating temperature of 170°F (77°C). Check fluid level and add if necessary.

PRESSURE TEST

1. Note pressure reading with valve open and engine idling. Pressure should be 80-125 psi (5.6-8.8 kg/cm 2 ).
2. If pressure is above 200 psi (14.1 kg/cm 2 ), check hoses for restrictions and poppet valve (Saginaw gears) for proper assembly.
3. Close gate valve completely and reopen 3 times. Record highest reading each time. DO NOT close valve for more than 5 seconds. If pressure is less than specification, clean or replace flow control valve in pump. If pressures are still low, replace pump.
4. If readings are within specifications and within 50 psi (3.5 kg/cm 2 ) of each other, pump is operating properly. See Pressure Test Specifications table. If pressures are high, but do not repeat within 50 psi (3.5 kg/cm 2 ), flow control valve in pump is sticking. Remove flow control valve and clean or replace.
5. If pump checks within specifications, open valve and turn steering wheel all the way from right-to-left stops and record pressure. DO NOT hold wheel against stops more than 5 seconds. Pressure should be the same as specified. See in Pressure Test Specifications table.
6. If pressure is low, steering gear is leaking internally and must be overhauled.

Note. If problem still exists, check ball joints, linkage, and other front suspension members.

SERVICE INTERVALS

Check with every oil change.

CHECKING FLUID LEVEL

Check fluid level with engine stopped and fluid hot or cold. Fluid level should be to "FULL HOT" or "FULL COLD" mark on dipstick. On models with remote reservoir, keep fluid level 0.5-1.0" from top of reservoir with wheels fully to the left.

RECOMMENDED FLUID

REFILLING & BLEEDING SYSTEM

1. Fill reservoir to correct level. Let oil settle for 2 minutes. Start engine and run for 2 seconds. Check reservoir and add oil if necessary. Repeat procedure until level in reservoir remains constant after running engine.
2. Raise front of vehicle so that both wheels are off ground. Start engine and increase engine speed to 1500 RPM. Turn wheels right and left, lightly contacting stops. Check fluid and add if necessary.
3. Lower vehicle. Turn wheels right and left. Check fluid level and add if necessary. If oil is foamy, allow vehicle to stand for a few minutes with engine off.
4. Repeat procedure with vehicle raised. Again check fluid level and for air in system. If level is low or there is air in system, repeat complete procedure.

PRESSURE SPECIFICATIONS

PRESSURE TEST SPECIFICATIONS (1)