Engine - Vibration at 1100-1300 RPM
89pontiac09Bulletin Number: 88-6-96
Reference Number: 906102
Publish Date: 5/89
Subject: ENGINE VIBRATION 1100-1300 RPM RANGE (NEW PART)
Models 1987-1988 BONNEVILLE MODELS WITH
Affected: 3.8L LG3 ENGINE (VIN CODE 3)
Some 1987-88 Bonneville models equipped with a 3.8L engine may exhibit a shake/vibration in the 1100-1300 engine rpm range. The condition could be described as a shake/vibration from the floor pan, seat, steering wheel and/or instrument panel at slow speeds (0-15 mph) or as a shudder/chuggle at speeds of 45-55 mph with the Torque Converter Clutch (TCC) engaged. To effectively minimize this condition, use the following repair procedure:
1. Verify engine performance.
^ All cylinders firing correctly
^ Expected normal ALDL scan tool readings
2. Check engine mounts for ground out or stress condition.
3. Remove the engine crankshaft balancer and install a new balancer, part number 25532179.
NOTICE: To ensure the interrupter ring on the new balancer has not been damaged prior to installation, use Kent-Moore Crankshaft sensor Adjusting Tool J-37089 to check concentricity of the interrupter ring and for correct crankshaft sensor adjustments.
Torque balancer bolt and washer to 270 N-m (200 ft.lbs.).
Parts are currently available from GMSPO.
4. Disconnect the exhaust pipe from the exhaust manifold. Using a high temperature anti-seize compound, lubricate the exhaust pipe seal (donut) and reinstall the pipe.
5. Remove the intermediate exhaust pipe hanger and rubber insulators. Refer to figure 1. Bend the hanger ends upward 1/2". Lubricate the rubber insulators with silicone grease and reinstall the hanger and insulators.
WARRANTY INFORMATION
Labor Operation Number: T5186
Labor Time: .8 Hours
Trouble Code: 92