1982 - 1993 Corvette: Service Bulletin: Buzzing Noise at Idle
Subject: BUZZING NOISE AT IDLE (INSTALL PRESSURE REGULATOR VALVE)
Model and Year:
1982-93 CAPRICE, CAMARO AND CORVETTE
1982-93 C/K, R/V, S/T, M/L AND G TRUCKS WITH 4L60 AUTOMATIC TRANSMISSION
Transmission Applications: 1982-1993 HYDRA-MATIC 4L60 (MD8)
Transmission Models: All
Vehicle Applications: B, D, F, Y - Cars C/K, R/V, S/T - Trucks G, M, L - Vans
Source: Chevrolet Service Bulletin
Bulletin Number: 93-29-7A
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.
The buzzing noise may be a result of pressure regulator valve oscillating due to oll pressure instability at lower idle RPM.
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