A/T - Buzz Condition Correction

Bulletin No. T 83-75
File In Group 7
Number 68
Date Apr. '83

NEW DESIGN PUMP ASSEMBLY TO ELIMINATE A "BUZZ" CONDITION - 1981-1982 THM 200-4R


New design pump assemblies were released for the THM 200-4R late in the 1982 model year. This new design eliminates a buzz condition that is caused by the pressure regulator valve. The design changes involve a new pump body, pump cover, and pressure regulator valve with orifice.

When servicing the pump body assembly or cover assembly on all 1981 and 1982 THM 200-4R transmissions, a complete pump assembly must be ordered (see chart below).

MODEL TRANSMISSION PUMP ASSEMBLY
YEAR MODEL NUMBER

1981-1982 BY 8639077
1982 AA, AP 8639077
1982 OM 8639135
1982 AH 8639079


MODEL TRANSMISSION PRESSURE REGULATOR
YEAR MODEL NUMBER

1981 & 1982 All Models 8637546

SERVICE INFORMATION

1. Follow proper Service Manual procedures for removal and installation of pump assemblies.

2. The solenoid and filter assembly must be removed before pulling the pump assembly from the case. Failure to follow this procedure can damage the solenoid, filter or "O" rings.

3. DO NOT MIX the old pump halves (body and cover) with the new design pump halves as this may create a "no drive" condition or may not eliminate the "buzz" condition.

4. New design pressure regulator valve listed above can be used with either new or previous design pump cover and body assemblies.