C 3500 Truck 2WD V6-262 4.3L (1990)
Drive/Propeller Shaft: All Technical Service Bulletins
Driveline - Vibration With Engine Under Load
Number:
90-322-7A
Section:
7A
Date:
August 1990
Corp. Bulletin No.: 077123
Subject:
DRIVELINE RATTLE VIBRATION WITH ENGINE UNDER LOAD, TCC APPLIED
Model and Year:
1989-90 K TRUCK WITH 4L60 (THM 700-R4) AUTOMATIC TRANSMISSION AND 4.3L (VIN CODE Z) ENGINE
TO:
ALL CHEVROLET DEALERS
BULLETIN COVERS;
Service and parts information for HYDRA-MATIC 4L60 (THM 700-R4) transmissions which may produce a driveline vibration or rattle with the engine
under load at approximately 40 mph and with the torque converter clutch (TCC) applied. This condition may occur in the following HYDRA-MATIC
4L60 (THM 700-R4) models that are used with 4.3L LB4 engines: 9MRM, OKAM
To reduce this condition, a torque converter containing damper springs with a higher spring rate and torque capacity has been released for production
and service.
DATE OF PRODUCTION CHANGE:
The following information shows the transmissions which are in vehicles that may exhibit, this condition:
Model
Date of Production
9MRM
All
OKAM
All
DIAGNOSIS INFORMATION:
The following diagnosis information will help you determine if a vehicle has the driveline noise or rattle condition:
-
Gear Range: Drive 4 (overdrive) with TCC engaged
-
Vehicle Speed: Beginning at approximately 40 mph (or higher) with TCC engaged - then step into the throttle slightly.
-
Conditions: 1. Noise, vibration or rattle
2.
Low frequency noise that builds up until the truck bed rattles
3.
Low growl or driveline grumble
Road grades or trailer loads may cause the conditions to be more prominent or extended.
The conditions should disappear when the TCC is disengaged. Brake can be lightly applied to disengage the TCC for testing.
SERVICE INFORMATION:
Converters replaced under this bulletin should be charged to Labor Code T8145. Do not use Labor Code K7020 as would normally be used for converter
replacements.
SERVICE PARTS INFORMATION:
Part Number
Description
8681952
Converter Asm. Pkg. 298 mm (DEAF)
Parts are expected to be available on August 27, 1990. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP
orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part
will be shipped premium transportation at dealer's expense. All other order types will be cancelled as incorrectly ordered while the 400 control is in
place.
SERVICE MANUAL REFERENCE:
