CAMPAIGN: ROCKER ARM ATTACHING PIN NOT FULLY SEATED
SUBJECT: ROCKER ARM ATTACHING PIN NOT FULLY SEATED U.S. Campaign Number Cross Reference: 96-C-07
Models: 1996 Chevrolet Corvette with LT4 Engine
TO: ALL GENERAL MOTORS DEALERS
General Motors of Canada Limited has determined that CERTAIN 1996 Chevrolet Corvettes equipped with 5.X engines (RPO LT4 - VIN Code "5") may have been built with rocker arms with attaching pins not fully seated to properly retain the roller. When improperly seated, the pin may back out, with a resultant engine failure likely to occur.
To correct this condition, dealers are to replace the rocker arm.
VEHICLES INVOLVED:
Involved are the following four (4) 1996 Chevrolet Corvettes equipped with 5.7L (RPO LT4) engines built:
VIN
1G1YY3256t5l0l467 1G1YY2252T5103713 1G1YY2252T5103744 1G1YY3258T5103348
All affected vehicles have been identified by the VIN listing provided to involved dealers with this bulletin. Any dealer not receiving a listing was not shipped any of the affected vehicles.
DEALER CAMPAIGN RESPONSIBILITY
All unsold new vehicles in dealer's possession and subject to this campaign must be held and inspected/repaired per the Service Procedure of this Campaign Bulletin before owners take possession of these vehicle.
Dealers are to perform this campaign on all involved vehicles at no charge to owners, regardless of kilometres traveled, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make the required correction according to instructions contained in this bulletin. This could be done by mailing to such owners a copy of the owner letter accompanying this bulletin. Campaign follow-up cards should not be used for this purpose, since the owner may not as yet have received the notification letter.
In summary, whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or is in your dealership for service in the future, please take the steps necessary to be sure the campaign correction has been made before selling or releasing the vehicle.
CAMPAIGN PROCEDURE:
Refer to Section 4 of the Service Policies and Procedures Manual for the detailed rocedure on handling Product Campaigns. Dealers are requested to complete the campaign on all transfers as soon as possible.
OWNERS NOTIFICATION:
All owners of record at the time of campaign release are shown on the attached computer listing and have been notified by first class mail from General Motors (see copy of owner letter included with this bulletin). The listings provided are for campaign activity only and should not be used for any other purpose.
PARTS INFORMATION:
Parts required to complete this campaign should be ordered through regular channels, as follows:
Part Number Description Quantity/Vehicle ----------- ----------- ---------------- 12551311 Rocker Arm Assembly 16
PARTS AND LABOR CLAIM INFORMATION:
Credit for the campaign work performed will be paid upon receipt of a properly completed campaign claim card or DCS transmission in accordance with the following:
Repair Code Description Time Allowance ----------- ----------- -------------- 2A Rocker Arm Replacement 1.2
Time allowance includes 0.1 hour for dealer administrative detail associated with this campaign. Parts credit will be based on dealer net plus 40% to cover parts handling.
SERVICE PROCEDURE:
ROCKER REMOVAL
LH SIDE
Note settings of all electrical devices and then:
1. Disconnect battery. 2. Remove fuel rail beauty cover. 3. Remove booster vacuum hose from intake manifold. 4. Remove distributor vent hose from intake manifold. 5. Remove fuel mil cover attaching studs. 6. Remove (2) hoses from A.I.R. check valve. 7. Loosen A.I.R. check valve tube at exhaust manifold and pivot away from rocker cover. 8. Remove air cleaner assembly. 9. Remove accessory drive belt. 10. Remove alternator bolts and rear bracket and lay alternator aside. 11. Remove (4) rocker cover bolts and cover. Cover gaskets are to be revised, set aside carefully to avoid damage.
RH SIDE
1. Remove fuel rail beauty cover. 2. Remove P.C.V. fresh air hose. 3. Remove (4) rocker cover bolts and cover.
ROCKER ARM REMOVAL AND REPLACE:
1. Rotate engine clockwise to TDC number 1 cylinder firing position. This can be done by watching number 1 cylinder valves as crankshaft balancer hub arrow approaches the 12 o'clock position. If a valve moves as arrow moves to position, engine assembly is in the number 6 cylinder firing position. Crankshaft must then be turned one more revolution to reach number 1 cylinder firing position. 2. In this position the following rocker arms should be replaced. Exhaust 1, 3, 4, 8 Intake 1, 2, 5, 7 3. Loosen rocker arm nut and lift rocker arms from stud. 4. Install new rocker arms. Be sure, push rod is properly seated in the lifter and rocker arms. 5. Install nuts and torque to 25 N.m (18 lb. ft.). 6. Rotate engine clockwise one more revolution until hub arrow is again at 12 o'clock position. This is number 6 cylinder firing position. 7. In this #6 firing position the following rocker arms should be replaced. Exhaust 2, 5, 6, 7 Intake 3, 4, 6, 8 8. Repeat Steps 3 through 6. 9. After rocker arm installation, be sure that the roller tip of the rocker arm is squarely seated on top of valve stem. Refer to 1996 Corvette Preliminary Service Manual, Section 6A1B-13, Figure 14.
ROCKER COVER INSTALLATION:
RH SIDE
1. Install (4) rocker cover bolts and cover. Torque bolts to 12 N.m (106 lb. in.). Original cover gaskets are to be reused. 2. Install P.C.V. fresh air hose. 3. Install fuel rail beauty cover.
LH SIDE
1. Install (4) rocker cover bolts and cover. Torque bolts to 12 N.m (106 lb. in.). Original cover gaskets are to be reused. 2. Install alternator, alternator bolts, and rear bracket. Torque front alternator bolts and bolt with nut to 50 Nm (37 lb. ft.). Torque rear bolts and bracket bolt to 47 N.m (35 lb. ft.). 3. Tighten A.I.R. chock valve tube at exhaust manifold and torque to 55 N.m (41 lb. ft.). 4. Install (2) hoses from A.I.R. check valve. 5. Install booster vacuum hose to intake manifold. 6. Install distributor vent hose to intake manifold. 7. Install fuel rail cover attaching studs. Torque studs to 12 N.m (106 lb. in.). 8. Install fuel rail beauty cover. 9. Install accessory drive belt. 10. Install air cleaner assembly. 11. Connect battery and reset all electrical devices as noted in Step 1. 12. Install Campaign Identification Label.
INSTALLATION OF CAMPAIGN IDENTIFICATION LABEL
Clean surface of radiator upper mounting panel and apply a Campaign Identification label. Make sure the correct campaign number is inserted on the label. This will indicate that the campaign has been completed.
Dear General Motors Customer,
General Motors of Canada Limited has determined that CERTAIN 1996 Chevrolet Corvettes equipped with 5.7L engines may have been built with rocker arms with attaching pins not fully seated to properly retain the roller. When improperly seated, the pin may back out, with a resultant engine failure likely to occur.
To correct this condition, your dealer will install new rocker arms in your engine.
This service will be provided for you at no charge.
Please contact your GM dealer as soon as possible to arrange a service date.
If parts are required, ask your dealer for details regarding their availability. If parts are not in stock, they can be ordered before scheduling your service date.
This letter identifies your vehicle. Presentation of this letter to your dealer will assist their Service personnel in completing the necessary correction to your vehicle in the shortest possible time.
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products.
Customer Support Department General Motors of Canada Limited
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.
