4 SP OR 5SP MAN. TRANSMISSION DIAGNOSIS AND EXCHANGE
MODELS: 1988 C/K TRUCKS WITH 4-SPEED (MCO) AND 5-SPEED (MG5) MANUAL TRANSMISSIONS
THIS BULLETIN COVERS:
Preliminary diagnosis and exchange procedure for the MG290 4 or 5-speed manual transmission.
Until further notice, any MG290 4 or 5-speed transmission needing repair will be exchanged for a new unit. The exchange program will be administered by Technical Assistance (TAS).
SERVICE INFORMATION
Transmission Identification Information.
Serial number tag location is on top of the front clutch housing (Figure No. 1).
Preliminary Diagnosis Procedure.
Insure correct oil level. Insure that the clutch is working properly. Insure that all engine and transmission mounts are tight.
SERVICE ACTION
Exchange ALL transmissions through Technical Assistance that require service except:
Clutch Release Bearing Service/Replacement Any Clutch Repair/Replacement
SERVICE MANUAL REFERENCE
Refer to Service Manual X-8731 (1988 C/K)
NOTICE: After removing the shift tower (exchange units are complete less shift tower assembly), cover the shift tower opening to prevent dirt from getting into the transmission during removal.
After installation of the new transmission, use P/N 1052942 Loctite (gasket maker) in place of the shift tower gasket until parts are available.
Do not force the shift tower onto the transmission, this will cock the socket on the bottom of the shift tower and may damage the machined surface.
The shift control lever and jam nut on the 4-speed are left handed, while the 5-speed has right hand threads.
EXCHANGE PROCEDURE
1. Reference Figures No. 1 - 3 and have information available before calling TAS. If the vehicle has an oil leak, determine where the leak is by using the oil leak identification chart. The noise and shifting charts can be filled in by using check marks. It will be necessary to record this information, as it will be needed to fill out the form on the transmission being retumed. (Blank form will be shipped with the new transmission.)
2. TAS will provide an authorized "Case Request Number". This number must be written on the clutch housing as well as the shipping container with a black marker pen.
3. TAS will arrange to ship an exchange unit to the dealership.
4. The exchange unit will have an envelope attached to it which contains:
Return Shipping Label
Administrative Procedures
MCO/MG5 Reporting Form (Reference Figures No. 2 and 3)
Return Shipping Carrier Information
Identification Tag
5. Once the exchange unit is received, the removed transmission is to be returned to:
Hydra-Matic (Muncie) 1200 West Eighth Street Muncie, IN 47302
6. The complaint unit must be returned within 8 to 10 days after the receipt of the exchange unit to avoid a chargeback.
PREPARATION FOR SHIPPING
1. Drain the oil and replace the drain plug.
2. Remove plastic shipping plugs from the exchange unit and install them into the removed unit.
3. Fold the MC0/MG5 reporting form, staple it to the identification tag and secure the tag to the clutch housing of the removed transmission.
4. Write the TAS "Case Request Number" on the clutch housing and shipping container with a black marker pen.
5. Repack the removed transmission into the exchange shipping container.
6. Place the shipping label on the shipping container.
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.
