POWER STEERING SHUDDER (INSTALL HIGH EXPANSION HOSE)

Subject: POWER STEERING SHUDDER (INSTALL A TUNED" OR HIGH EXPANSION HOSE)

Models Affected: 1989-91 SUNBIRD AND GRAND AM MODELS W/3.1, 2.3, AND 2.5, ENGINES

This bulletin cancels and replaces bulletin 90-3-9B issued 2190. Please discard bulletin 90-3-9B.

MODELS/YEARS:

1991 Sunbird models w/3.1L (VIN T) Engine 1990 Grand Am models w/2.3L (VIN D or A) Engine 1989-91 Grand Am models w/2.5L (VIN U) Engine

Condition: Customers may comment about a shudder, moan or vibration that occurs when turning the steering wheel under the following conditions:

- Vehicle stopped with brake applied (or moving very slowly) - Vehicle in gear - Engine at idle speed

The shudder or moan may occur during parking maneuvers or other situations when the steering wheel is turned while the vehicle is stopped or moving very slowly. It is also sensitive to steering wheel rotational speed as well as engine speed. The shudder is commonly more severe during hot ambient temperatures.

Cause: A combination of steering gear valve instability and/or engine firing pulses generating a disturbance that is transmitted through the body structure.

Correction: Install a "tuned" power steering return hose and/or high expansion pressure hose between the steering pump and gear.

1990-91 Sunbird models w/3.1L (VIN T) Engine --------------------------------------------- Starting with the VIN breakpoint (Lordstown) M7526173, 1991 model vehicles were built with a new high expansion pressure hose which corrects this condition. Vehicles built BEFORE the VIN breakpoint listed may be repaired by installing a new high expansion pressure hose, P/N 26026623.

1990 Grand Am models w/2.3L (VIN D or A) Engine ------------------------------------------------ Starting with the following VIN breakpoint, 1990 vehicles are also equippcd with a new "tuned" return hose which further reduces the shudder condition:

"TUNED" RETURN HOSE

(Lansing B) LC252285

Starting with the following VIN breakpoint, 1990 vehicles are also equipped with a new high expansion pressure hose which further reduces the shudder condition:

NEW PRESSURE HOSE

(Lansing B) LC305247

On vehicles built BEFORE the above listed "TUNED BETURN HOSE" breakpoint, the shudder condition may be repaired by installing a "tuned" return hose, P/N 26023904. In a very limited number of cases, the tuned return hose may not completely eliminate the shudder condition. In these cases, the condition may be repaired by installing a new high expansion pressure hose, P/N 26024244 (and removal of the clip from the power steering pump).

Vehicles built ON OR FOLLOWING the above listed "TUNED RETURN HOSE" VIN breakpoints, but before the above listed "NEW PRESSURE HOSE" VIN breakpoints, are equipped with tuned return hoses, but are not equipped with new high expansion pressure hoses. For vehicles in this range that still exhibit some power steering shudder, the condition may be repaired by installing a new high expansion hose, P/N 26024244 (and removal of the clip from the power steering pump). Vehicles built after the above listed "NEW PRESSURE HOSE" VIN breakpoints are equipped with a "tuned" return hose and a new high expansion pressure hose and should not exhibit the shudder condition.

1990-91 Grand Am models w/2.5L (VIN U) Engine ---------------------------------------------- Starting with the following VIN breakpoint, 1991 vehicles are being built with a new "tuned" return hose which corrects this condition;

(Lansing B) MC541388

In vehicles built before this VIN breakpoint, this condition may be repaired by installing a new "tuned" return hose, P/N 26027298.

To repair vehicles with tuned return hoses that still exhibit steering shudder, install a high expansion pressure hose, P/N 26027234.

Note: If the above hoses do not repair the shudder condition, please contact Technical Assistance.

Parts are currently available from GMSPO.

Labor Operation Number: Pressure Hose E8622 Labor Time: See Current Labor Time Guide Trouble Code: 92

Labor Operation Number: Return Hose E8623 Labor Time: See Current Labor Time Guide Trouble Code: 92

ENGINE MODEL VIN MODEL PART YEAR/ VIN CARLINE ENGINE CODE YEAR HOSE TYPE NUMBER BREAKPOINT NOTE ----- -------- ----- ---- ----------- -------- ------- ---- J 3.1 L LHO T 1991 HIGH EXPANSION 26026623 1991 - 2 M7526173 N 2.3L D or A 1990 TUNED RETURN 26023904 1990 - 2 LD2/LGO LC252285 N 2.3L D or A 1990 HIGH EXPANSION 26024244 1990 - 1,2 LD2/LGO LC305247 N 2.5L L68 U 1989-91 TUNED RETURN 26027298 1991 - 2 MC541388 N 2.5L L68 U 1989-19 HIGH EXPANSION 26027234 SERVICE ONLY 3

NOTE:

1 USE RETURN HOSE P/N 26023904 BEFORE INSTALLING THIS NEW PRESSURE HOSE. REMOVE P/S PUMP HOSE CLIP.

2 VEHICLES BUILT AFTER THIS BREAKPOINT ALREADY CONTAIN THIS HOSE.

3 USE RETURN HOSE P/N 26027298 BEFORE INSTALLING THIS NEW PRESSURE HOSE. IF THE HOSES LISTED ABOVE DO NOT WOPK PLEASE CONTACT TECHNICAL ASSISTANCE.

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.