SLIP OR NO DRIVE RESULTING FROM LOW LINE PRESSURE

BULLETIN COVERS:

A slip or no drive condition on a THM 440-T4 transaxle may be caused by low line pressure due to the pump slide binding on excessive casting flash when the slide is in the low pressure position. Modulator vacuum will not affect line pressures if this candition is present. This condition can be repaired by replacing the oil pump assembly.

DATE OF PRODUCTION (Figure 1)

A THM 440-T4 transaxle built between November 26, 1986 (Julian Date 330) and January 12, 1987 (Julian Date 012) may exhibit this condition.

SERVICE ACTION (Figure 2)

Remove oil pump cover and pump priming springs and move the slide by hand. If excessive flash is present the slide will bind in the area indicated in Figure 2.

SERVICE PARTS INFORMATION:

Refer to GM Parts Catalogue for part number information.

SERVICE MANUAL REFERENCE

Refer to THM 440-T4 (ME9) Automatic Transaxle Unit Repair Table of Contents for oil pump service information.

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.