RACK/PINION POWER STEERING VALVE RING SERVICE

MODELS AFFECTED: 1982-1984 CIMARRONS

This bulletin supersedes Serviceman Bulletin T-81-68, Group 3B, Number 5, which should be destroyed.

Some 1982 to 1984 Cimarrons may experience a lack of power steering assist on cold starts. When diagnosing this condition, first check power steering pump pressure using procedures found in Section 3 of the appropriate Service Information Manual. If pump pressure is normal, disassemble rack and pinion gear and inspect for one of the following two conditions.

A. Power Steering Valve Ring Wear ------------------------------ The power steering valve and pinion assembly is designed to rotate in the rack housing with the valve body rings remaining stationary in the bore. In some cases, one or more of the valve rings may be caused to rotate with the valve assembly due to lack of retention at the housing bore, or ring drag at the valve ring lands. Rotation of the valve rings may eventually cause the housing valve bore to wear, creating lack of assist on cold starts.

Ring contact marks on the valve bore are normal (Figure 1). If ring grooves have worn into the housing bore surface, valve rings and housing (P/N 7846635) must be replaced. Failure to replace the housing may allow replacement rings to wear further into valve bore, resulting in a recurrence of the lack of assist condition.

If fewer than four of the ring contact marks on the valve bore show abnormal wear, the corresponding valve ring lands should be checked for excessive ring drag. Inspect valve ring lands for burrs or imperfections which may restrict ring rotation. Remove any burrs with a hone. If replacement rings will not rotate freely on the valve, the valve (P/N 7844631) should also be replaced.

Orange-colored valve rings have been phased into 1984 production, replacing the green rings used in 1983 and early 1984 models. The service ring kit (P/N 7840573) will continue to use green rings which are interchangeable with orange production parts.

In late 1984 production, the rack and pinion housing valve bore will be given a textured finish to help ensure that the valve rings remain stationary in the housing.

NOTICE: The procedure for valve removal and valve ring replacement is listed in Section 3B2 of the 1984 Cimarron Service Information Manual. The valve must be pressed out of the housing per the listed procedure. Use of a hammer or other means of excessive force may damage the valve or valve pinion pin.

After valve removal, inspect the valve pinion pin. If the pin is loose, bent or protruding beyond the machined valve surface, the valve body should be replaced (see Figure 2).

B. Fluid Leakage Past Rack Piston Ring ----------------------------------- A lack of power assist condition may also be caused by fluid leakage past the rack piston ring in the housing tube bore. Inspect the rack piston ring for damage or distortion. Piston ring to ring land side clearance should not exceed 0.20mm (0.008"). The housing tube bore should also be inspected for nicks, scoring or other imperfections in the rack piston travel area. Replace the rack piston ring (P/N 7838287) if excessive clearance or other imperfections exist.

For warranty purposes, use labor Operation No. E9720 at 2.6 hours (manual trans.) or 2.7 hours (automatic trans.).

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.