Engine Mount/Exhaust System - Vibration
Bulletin No.: 004/96Issued: 06/27/96
Revised:
Category
R
Applicable Model/s
1991 - 94 Navajo
Subject:
VIBRATION/SHAKE ON SMOOTH ROADS (+50MPH) VIBRATION/SHAKE OVER BUMPS (-45MPH)
APPLICABLE MODELS/VINS
1991-94 Navajo
DESCRIPTION
Some vehicles may experience a vibration/shake felt in the seat and/or floor at speeds above 50 MPH and peaking near 65 MPH. This concern does not depend on engine RPM and occurs in all driving modes (i.e. acceleration, cruise and deceleration). An "after shake" concern may also exist when driving over a bump at less than 45 MPH. This concern may lessen after tire balancing or replacement, but is not completely eliminated.
The cause of this concern may be the result of the movement frequency of the engine aligning with the tire rotation frequency.
Customers complaining of this concern should have the vehicle inspected according to the instructions in this bulletin and if necessary, have the revised engine mounts (left and right), rear axle-to-frame lateral shock absorber kit and main silencer tail pipe assembly installed.
NOTE:
^ Service Managers should place a copy of this bulletin in the NVH manual.
^ This bulletin does not apply to vehicles with engine block heaters. Inadequate clearance exists for new engine mount installation with block heaters installed.
^ This repair will not compensate for the following:
a) Out-of-round or out-of-balance wheel/tire assemblies.
b) Vibration resulting from abnormal or irregular tire wear.
c) Other tire/wheel quality or out-of-specification issues.
INSPECTION PROCEDURE
1. Verify that the vibration/shake occurs in all driving modes including neutral coast.
^ If the concern occurs as specified, proceed to step 2.
^ If the concern does not occur as specified, refer to the NVH manual for trouble-shooting and repair instructions.
2. Visually inspect the tires for abnormal or irregular wear patterns. If necessary, replace the tire(s) with the original equipment size and type.
3. Set the tire pressure to the specification listed on the calibration label located on the driver's side B pillar.
4. Check the wheel/tire balance, repair as necessary.
5. Test drive the vehicle.
^ If the vibration/shake still exists, install the revised engine mounts and rear axle-to-frame lateral shock absorber kit. Refer to Fig. 1, 2, and 3. Installation instructions are shown.
^ If the vibration/shake is not present, return the vehicle to the customer and explain the source of the problem.
6. Replace the main silencer, tail pipe assembly and gasket.
NOTE:
The main silencer and tail pipe assembly must be replaced on all vehicles with or without a resonator.
a) Raise the vehicle on a hoist and remove the right rear tire/wheel assembly.
b) Remove the main silencer-to-catalyst attachment bolts.
c) Remove the tail pipe hanger rod from the insulator.
d) Remove the main silencer hanger rods from the insulators.
e) Remove the main silencer assembly from the vehicle.
f) Remove and replace the main silence-to-catalyst gasket.
g) Install new main silencer assembly.
h) Insert main silencer hanger rods into insulators.
i) Insert tail pipe hanger rods into insulators.
j) Assemble main silencer-to-catalyst Tightening Torque: 30 ft-lbs. (40 Nm).
k) Lower vehicle.
7. Road test vehicle.
^ If the concern is repaired, return the vehicle to the customer.
^ If the concern is still present, the tire/wheel assemblies may require service.
PARTS INFORMATION
WARRANTY INFORMATION
(Applies To Verified Customer Complaints On Vehicles Covered Under Normal Warranty. Refer To The SRT Microfiche For Warranty Term Information)
Warranty Type: A
Symptom Code: 83
Damage Code: 9J
Part Number Main Cause: ZZLC-39-042
Quantity 1
Operation Number: YY0249RX
Labor Hours: 3-4 Hrs
DISCLAIMER