A/T - Buzzing Noise at Idle

Number: 93-29-7A
Section: 7A
Date: OCT. 1992
Corporate Bulletin No.: 277142
ASE No.: A2

Subject:
BUZZING NOISE AT IDLE

Model and Year:
1982-93 CAPRICE, CAMARO AND CORVETTE
1982-93 C/K, R/V, S/T, M/L AND G TRUCKS WTIH 4L60 AUTOMATIC TRANSMISSION

TRANSMISSION APPLICATIONS:
1982-1993 HYDRA-MATIC 4L60 (MD8)

TRANSMISSION MODELS:
All

SUBJECT:
Pressure Regulator Valve Buzz

VEHICLE APPLICATIONS:
B, D, F, Y - Cars C/K, R/V, S/T Trucks G, M, L - Vans

CONDITION:

Some 1982-1993 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 (III. 218) has been made which will improve the oil pressure stability at lower RPM.

SERVICE PARTS INFORMATION:

Description Part Number
Valve, Pressure Regulator (III. 218) 8684048

Part numbers are for Reference Only.
Check with your Parts Department for latest information.

Labor Operation No.: K6550 Valve, Pressure Regulator-R&R or Replace

Use the appropriate labor time in the labor time guide.

Parts are currently available from GMSPO.