1988 - 1990 Corvette: Service Bulletin: Power Steering Shudder / Groan

Subject: POWER STEERING SHUDDER/GROAN INSTALL P/S COOLER & HOSE
Model and Year: 1988-90 CORVETTE WITH 5.7L ENGINE
Source: Chevrolet Service Bulletin
Bulletin Number: 90-376-3B - (10/25/1990)

Condition:

Some 1988-90 Y-cars with either L98 or LT5 engines and assembled prior to VIN breakpoint L5115181 or L5802113 respectively, may exhibit a slight power steering related shudder/groan condition. This condition is typically apparent during either static or low speed turning maneuvers and may be perceived by the vehicle operator as a vibration felt in the vehicle’s steering wheel.

Cause:

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

Correction:

Utilizing model year/engine - suspension RPO matrix shown below, determine applicable steps to be performed on the vehicle being serviced. When determining corrective action for 1990 vehicles, attention must be paid to VIN breakpoints.

ENGINE/SUSPENSION RPO 1988 1989 1990

---------------------- ------- ------ ------------

L98/FE7 A and B A and B A*, B and E@ (Finned Power Steering Cooler)

L98/FE1 B and C B and C B, C* and E@ (Loop Power Steering Cooler)

LT5/ZRl -- -- D# and E+

* SOP thru 115181 @ 113000 thru 115181

+ 801883 thru 802113 # SOP thru 802113

Steps Labor Operation Number Labor Time

----------- ---------------------- ----------

A and B T1682 1.2 Hour

B and C T1682 1.3 Hour

A, B and E T1682 4.3 Hour

B T1682 .9 Hour

B, C and E T1682 4.3 Hour

D and E T1682 4.1 Hour

D T1682 .8 Hour

Trouble Code: 92

Parts are currently available from GMSPO.

STEP A

Replace existing return hose (steering gear to cooler) with new assembly with internal tuner cable.

Part Description P/N QUANTITY

--------------- ------- ------

Return Hose 26024247 1

Clamp 477402 2

STEP B

Replace existing pressure/inlet hose (pump to steering gear) with new assembly with internal tuner cable.

PART DESCRIPTION P/N QUANTITY

--------------------- ------- --------

Pressure/inlet Hose Asm. 26027177 1

STEP C

Replace existing power steering loop/pipe cooler with finned cooler that includes return hose with tuner cable.

PART DESCRIPTION P/N QUANTITY

------------------- ------------- ---------

Power Steering Finned Cooler Assembly 26027162 1

Screw (Bracket To Cooler) 11508600 4

* Mounting Bracket 26006632 1

* Bolt (Bracket to Frame) 11514532 4

* Nut (Bracket To Frame) 11507036 4

* Required Only on 1988-89 model year vehicles.

STEP D

Replace existing pressure inlet hose (pump to steering gear) with new assembly with internal tuner cable.

PART DESCRIPTION P/ N QUANTITY

---------------- -------- --------

Pressure/Inlet Hose Asm. 26025628 1

STEP E

On applicable 1990 vehicles as designated by VIN breakpoints indicated in step matrix, replace existing power steering gear.

PART DESCRIPTION P/N QUANTITY

---------------- -------- --------

Steering Gear 26024923 1

When performing these corrective action steps, applicable Service Manual procedures must be followed to insure proper component installation and system operation.

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.