POWER STEERING SHUDDER USE INSPECTION ANALYSIS CHART. Buick Century 1991

SUBJECT: POWER STEERING SHUDDER (USE INSPECTION/ANALYSIS CHART)

MODELS AFFECTED: 1989-92 CENTURY WITH 3300 ENGINE (VIN CODE N)

THIS BULLETIN IS BEING REVISED TO ADD MODEL YEAR 1992 AND BREAKPOINTS FOR STEPS A AND B. PLEASE DISCARD PREVIOUS BULLETIN 91-3-16.

CONDITION:

--------- Some 1989-92 Century models with 3300 V6 engines (RPO LG7) may exhibit power steering shudder, a pulsing or resonating disturbance that the vehicle operator may hear and feel through the body structure and steering wheel. This condition is most apparent at low engine RPM and/or while making low speed turns.

CAUSE:

----- A combination of power steering pump pressure pulses and engine firing frequency generating a disturbance transmitted through the body structure.

CORRECTION:

---------- Utilizing the Inspection/Analysis Chart shown below, determine which of the power steering or engine components indicated have NOT been previously installed on the suspect vehicle.

INSPECTION/ANALYSIS CHART ------------------------- OTHER PART PART VIN BREAK INSPECTION STEP DESCRIPTION NUMBER POINT NOTES --------------------------------------------------------------------------- A Power Steering 26030820 New tuned hoses inlet/pressure have internal hose. metal cores.

BUICK: To check, place Okla. City magnet on hoses. N 6405734 New hoses will attract magnet; Ramos Arizpe original hoses N 5604012 will not.

B Power Steering 26017135 N/A outlet/return IMPORTANT: hose. Check both hoses. (steering gear One or both may to cooler pipe) require replacement

C Power steering 26030491 BUICK: There are no pump Ramos Arizpe obvious external MS621630 differences Okla. City between original M6430960 and new pumps. Use VIN Breakpoint to determine if replacement is required.

D Crankshaft 12339997 Start of New isolated Balancer Kit Production crankshaft 1991 balancer/pulley assembly is approximately 2 inches in width, while old style is only about 1 inch in width.

Parts are currently available from GMSPO.

Install those components not found on the vehicle after performing the above inspection, following applicable Service Manual procedures and in the case of the crankshaft balancer kit, those indicated below:

CRANKSHAFT BALANCER KIT INSTALLATION PROCEDURE:

Remove or Disconnect

1. Negative battery cable

2. Serpentine belt

3. Raise car and suitably support, see Section OA

4. Right front wheel and tire assembly

5. Inner fender splash shield (right side)

6. Torque converter cover

7. Hold flywheel with tool J-37096

8. Balancer bolt

9. Crankshaft balancer

IMPORTANT: --------- The balancer is serviced as an assembly. Do not attempt to separate pulley from balancer hub.

Install or Connect

1. Crankshaft balancer

o Lubricate seal surface with engine oil

2. Balancer bolt and washer

o Hold flywheel with tool J-37096

o Balancer bolt to 140 N.m (103 lbs. ft.)

- Loosen bolt to finger tight

- Utilizing tool J-36660, retorque to 150 N.m (110 lbs. ft.) plus 56 degrees

3. Inner fender splash shield

4. Right front wheel and tire assembly

5. Torque converter cover

6. Lower car

7. Serpentine belt

8. Negative battery cable

Note: After installation of either of the hose assemblies and/or pump, it is essential that the system be properly bled following the procedure in the 1992 Service Manual.

WARRANTY INFORMATION:

Labor Operation Number: T1743

Labor Time: Step "A" - 1.2 Hours Steps "A and B" - 1.3 Hours Steps "A and C" - 1.6 Hours Steps "A, B and C" - 1.7 Hours Steps "A, C and D" - 2.0 Hours Steps "A, B, C, and D" - 2.1 Hours

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.