Steering System - Power Isuzu Impulse I

DESCRIPTION

Power-assisted rack and pinion steering system consists of a vane pump, rotary valve assembly, and an oil reservoir.

The vane pump draws fluid from the reservoir and supplies it to the valve assembly. The rotary valve in the valve assembly supplies fluid to the proper side of the rack piston, when the steering wheel is turned.

The belt-driven pump mounts on the front of the engine. The reservoir is remote mounted, connected by hoses to the vane pump.

STEERING PUMP PRESSURE

1. Install Pressure Gauge (J-29877-A ) with shut-off valve between steering gear and power steering pump. Connect the gauge hose furthest from the shut-off valve to the back of the power steering pump.
2. Fill fluid reservoir. Bleed air from system. Open shut-off valve. Start engine. Set idle speed to 1500 RPM.
3. Measure fluid pressure when steering wheel is turned to lock in both directions. Pressure should be 925-1067 psi (65-75 kg/cm 2 ).
4. If pressure is higher than specified, oil pressure relief valve in power steering pump is defective. If pressure is lower than specified, place steering wheel in straight-ahead position.
5. Close stop valve completely. Hold engine speed at 1500 RPM. If pressure is now normal, steering gear is defective. If pressure is still low, power steering pump is defective.

CAPACITY

1.5 pints (.7L).

FLUID TYPE

ATF Dexron.

Scheme 1

HYDRAULIC SYSTEM BLEEDING

Fill fluid reservoir. Raise and support vehicle. Start engine. Turn steering wheel lock-to-lock 3 or 4 times. System is free of air when there is no buzz in hydraulic line. Also, fluid level should not increase with wheels in straight ahead position and engine stopped.

BACKLASH

Install the 7 shims, .002" (.05 mm) each, from the overhaul kit in the steering housing. Install valve housing assembly. Tighten to specification. Measure the clearance between mating surfaces of steering housing and valve housing. Remove shims equivalent to thickness of clearance. Apply liquid sealer to mating surfaces. Tighten to specification.

ADJUSTING PLUG

Tighten adjusting plug to 58 INCH lbs. (6.5 N.m). Loosen adjusting plug. Repeat these procedures twice. Tighten to specification again. Back off adjusting plug 30-35 degrees (approximately 1/10 turn). Tighten lock nut.

POWER STEERING VALVE CLEARANCE

1. Center the steering rack. Measure between seal holder and end of rack. Measurement should be 2.5" (65.5 mm). Grease pinion gear teeth and pinion ball bearing. Using the valve adjusting kit, install all 7 shims.
2. Install pinion valve assembly to housing. Carefully tighten attaching bolts 1/4 turn at a time until snug. Using a feeler gauge, measure clearance between valve assembly housing and gear box.
3. Note the measurement. Disassemble and remove shims as necessary, to allow a maximum .002" (.50 mm) clearance when reassembled. Reassemble valve housing to gear box. Seal mating surface with RTV Sealant (1052366 ).
4. Center steering rack using marks made during disassembly. See «STEERING GEAR»(/isuzu/impulse/i-1983-1990/remont/manual-power-steering/#steering-system-power) in OVERHAUL procedure of this article. Align pinion shaft so that flat side of splines is parallel with steering rack.
5. Install rack plunger, spring, adjusting plug and lock nut. Tighten adjusting plug to 43 INCH lbs. (5 N.m). Loosen plug. Retighten plug to 43 INCH lbs. (5 N.m). Back off plug 30-35 degrees.
6. Using an INCH lb. torque wrench and socket, check pinion shaft preload. Preload should be 5-14 INCH lbs. (.6-1.6 N.m). If not within specification, loosen lock nut and reset plug preload.

Removal (I-Mark)

1. Disconnect negative battery cable. Remove hood. Raise and support vehicle. Remove front wheels. Disconnect tie rod ends from steering knuckles.
2. Remove engine mounting bolts. Raise engine slightly. Support engine with floor jack. Disconnect front exhaust pipe hanger. Remove engine mounting crossmember.
3. Remove protector from steering shaft. Remove bolts from steering intermediate shaft. Remove shaft.
4. Disconnect and plug power steering fluid lines. Remove steering gear mounting bolts. Lower steering gear from vehicle.

Removal (Impulse)

1. Raise and support vehicle. Remove front wheels, disc brake calipers (do not disconnect lines), and rotors. Separate tie rod ends from steering arms. Separate steering column from steering gear.
2. Note installed position of power steering fluid lines. Disconnect and plug lines. Remove gear-to-frame mounts. Lift off steering gear.

Installation (All Models)

To install, reverse removal procedure. Bleed air from system.

Removal & Installation

Remove engine undercover (Impulse). Loosen pump bracket and remove drive belt from pulley. Disconnect and plug power steering fluid lines. Remove pump mounting bolts. Lift out pump.

STEERING GEAR

Disassembly

1. Place steering gear in vise. Move dust boots toward tie rod end. Hold rack with wrench while unscrewing tie rod. Mark position of stub shaft relative to rack shaft. Remove valve housing and valve assembly.
2. Record number of shims removed. Shims are used for adjusting backlash between rack shaft and pinion shaft if rack shaft, valve housing, and valve assembly are to be reused.
3. By inserting a pin punch into the hole at the outer circumference of steering gear housing, remove rack retaining ring. Carefully remove oil seals, rack shaft, and back-up ring. Remove seal ring from rack shaft.
4. Remove valve assembly from valve housing. Remove sleeve from stub shaft. Remove all "O" rings and seals from sleeve. Drive oil seal out of valve housing.

Inspection

1. Inspect all parts for excessive wear or damage. If the inner wall is scored or damaged, replace cylinder assembly. Sleeve and rotor are precision-machined and must be replaced as an assembly (if necessary).
2. Replace the track rod assembly if any play is felt when moving the ball on tie rod. Clean all parts with compressed air before reassembly.

Reassembly

1. Using Oil Seal Installer (J-33997-7 ), install center oil seal on stub shaft with seal lip toward rotor. Replace all seals and "O" rings on sleeve and valve assembly.
2. Assemble sleeve and valve assembly. Pin on sleeve must be properly fitted into groove at rear end of oil seal. Install retaining ring. Install oil seal and ball bearing in end of valve housing. Install valve assembly in valve housing.
3. Place new seal ring, back-up ring, holder assembly, and oil seal on rack shaft. Lubricate all seals with clean ATF. Install rack shaft in cylinder. Distance between tip of rack shaft and end of housing should be approximately 3" (7.6 mm).
4. Install original valve assembly shims in the steering housing. If valve housing assembly, valve assembly, rack shaft, or steering housing has been replaced, new shims will have to be installed and backlash adjusted at this time. See «ADJUSTMENTS»(/isuzu/impulse/i-1983-1990/remont/manual-power-steering/#steering-system-power) in this article.
5. Install valve housing with oil pipe fitting face turned toward the adjusting plug opening. Recess for pinch bolt at serrated portion of stub shaft must be pointed away from the adjusting plug opening.
6. Tighten valve housing bolt to specification. Install adjusting pad, spring, and plug in steering housing. See «ADJUSTMENTS»(/isuzu/impulse/i-1983-1990/remont/manual-power-steering/#steering-system-power) in this article.
7. Install tie rods on rack ends. Tighten to specification. Install boots.

1. Clamp pump in vise. Remove front bolts. Carefully remove front body assembly from rear assembly. Carefully disassemble front body side assembly.
2. To remove drive shaft from front body, tap on splined end with plastic hammer. Remove oil seal from pump body. Remove "O" rings, flow control valve, pressure sensing valve, and springs from rear body.

Inspect all parts for scoring, wear, or damage. The main and subcartridge assembly in the front body are precision finished, and must be replaced together, if worn or damaged. Pressure sensing valve and flow control valve must also be replaced (if defective). Check drive shaft for excessive runout.

1. Wash all parts in solvent. Blow dry with compressed air. Lubricate parts with ATF before reassembly. Install "O" rings, flow control valve, and pressure sensing valve in rear body.
2. Install oil seal and drive shaft with bearing into front body. Assemble front body side main and subcartridges, and side plates. Set chamfered face of main cartridge to rear body side.
3. Install front body assembly into rear body assembly. Install bolts. Tighten to specification.

Scheme 2

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• STEERING GEAR