A/T - Buzzing Noise at Idle

Bulletin Number: 93-7-5
Reference Number: 277142
Publish Date:10/92

Subject:
BUZZING NOISE AT IDLE (INSTALL NEW PRESSURE REGULATOR VALVE)

Models Affected:
1984-1993 FIREBIRD MODELS W/4L60 TRANSMISSION

TRANSMISSION APPLICATIONS:
1984-1993 HYDRA-MATIC 4L60 (MD8)

TRANSMISSION TYPE 4L60 700R4

TRANSMISSION MODELS: All

CONDITION:

Some 1984-1993 vehicles equipped with a HYDRA-MATIC 4L60 transmission may have a buzzing noise coming from the transmission when the vehicle is at idle. The buzzing noise may be noticed more when the vehicle is in reverse at idle.

CAUSE:

The buzzing noise may be a result of pressure regulator valve oscillating due to oil pressure instability at lower idle RPM.





CORRECTION:

A new pressure regulator valve (Ill. 218) has been made which will improve the oil pressure stability at lower RPM.

SERVICE PARTS INFORMATION:

Description Part Number

Valve, Pressure Regulator (Ill. 218) 8684048
Parts are currently available from GMSPO.

WARRANTY INFORMATION:
Labor Operation No.: K6550
Labor Time:
Use Applicable Labor Time.