A/T - Buzzing Noise on Engine Shutdown

BULLETIN NUMBER:
93-7A-17

SECTION:
7A

NUMBER:
3

CORPORATE
REFERENCE NUMBER:
277141

DATE:
October 1992



SUBJECT:
BUZZING NOISE ON ENGINE SHUTDOWN (INSTALL NEW PRESSURE REGULATOR VALVE)

MODELS:
1993 C/K, S/T TRUCKS AND G/M/L VANS WITH 4L60E TRANSMISSION



CONDITION:
Some 1993 vehicles equipped with the HYDRA-MATIC 4L60-E transmission may exhibit a buzzing noise coming from the transmission on engine shutdown.

CAUSE:
The buzzing noise may be a result of the pressure regulator valve oscillating due to oil pressure instability during engine shutdown.

CORRECTION:





A new pressure regulator valve (See Figure 1) has been released which will improve the oil pressure stability at lower RPM.



SERVICE PARTS INFORMATION:

Part
Description Number
Valve, Pressure Regulator (See Figure 1) 8684041

Parts are expected to be available on October 5, 1992. In case of limited inventory, parts will be placed on 400 control to waive VIP surcharges. Only verifiable emergency VIP orders will be accepted. GMSPO will make every effort to obtain parts. However, the part will be shipped premium transportation at dealer's expense and all other order types will be placed on back order until the 400 control is removed.

WARRANTY INFORMATION:

Labor Operation:
K6550 Valve, Pressure Regulator - R&R or Replace

Use the appropriate labor time in the labor time guide.