A/T - Slip Bump During 3-2 Gear Downshift
88buick04Bulletin: 88-7125-5
Date: Mar., '88
Ref. No.: 88-095-7125
Corp. Ref. No.: 877118
SUBJECT: SLIP BUMP DURING 3-2 DOWNSHIFT
MODELS AFFECTED: 1988 SKYLARKS EQUIPPED WITH 2.3L (VIN CODE D), OR 3.0L (VIN CODE L) ENGINES, AND THM 125C (MD9) TRANSAXLE MODELS BHC, BJC, KDC
BULLETIN COVERS
A Slip Bump condition during a part throttle 3-2 downshift (Forced Throttle) maneuver, may be caused by excess material left in the 3-2 control valve bore during machining of the Control Valve and Oil Pump Assembly.
FIGURE 1 - THM 125/125C TRANSAXLE IDENTIFICATION INFORMATION:
DATE OF PRODUCTION CHANGE (Figure 1)
November 11, 1987 (Julian Date 315) corrected control valve assemblies went into production.
SERVICE ACTION
To repair this condition on a 1988 N Car with a 2.3L or 3.0L Engine and equipped with a THM 125C with a listed Julian Date lower than 315 install a new Control Valve and Oil Pump Assembly.
FIGURE 2 - CONTROL VALVE AND OIL PUMP ASSEMBLY:
SERVICE PARTS INFORMATION (Refer to Figure 2)
When ordering a new Control Valve and Oil Pump Assembly refer to the following part list:
Part No. Package Description Models
8664791 Control Valve and Oil Pump Assembly BHC
8664791 Control Valve and Oil Pump Assembly BJC
8664794 Control Valve and Oil Pump Assembly KDC
SERVICE MANUAL REFERENCE
When servicing a 125C transaxle for this condition replace the Control Valve and Oil Pump Assembly. Refer to the procedure given in 125/125C Unit Repair Section of your Service Manual.
WARRANTY INFORMATION
Labor Operation Number: K6570.