K 30 P/U 4WD V6-262 4.3L (1985)
Cross-Member: Customer Interest
Vehicle - Vibration in 1500-2500 RPM Range
CHEVROLET NUMBER: 86-T-211
SECTION:
6A - Engine Mechanical
DATE:
January, 1987
SUBJECT:
VEHICLE VIBRATION
MODELS:
1985-86 C1 AND C2 TRUCKS WITH THE 4.3L V6 ENGINE AND THM 400 TRANSMISSION
Some 1985-86 C1 and C2 trucks with the 4.3L V6 may experience a vehicle vibration in tHe 1500-2500 rpm range. This condition may be the result of
the natural frequency second order vibration of the 4.3L V6 engine which is then amplified by the other powertrain components such as the transmission,
transmission crossmember, and the center support bearing crossmember for the two-piece propshaft. Vehicles exhibiting this condition can be repaired
by using the following procedure:
FIGURE NO. 1 - ENGINE TO TRANSMISSION STRUT BARS
Procedure
1.
Road test the truck to verify the complaint.
2.
Inspect the truck to make sure no components are loose or grounding out against the frame such as the exhaust system, hoses, and lines, etc.
3.
Check vehicle to make sure engine to transmission strut bars are on the vehicle, see Figure No. 1. If strut bars are missing, they must be installed.
Refer to section 0.00 page 0-26, of the C/K parts book illustrations for part numbers.
4.
Re-index the torque converter to try to reduce the vibration.
