Skylark L4-138 2.3L DOHC VIN D MFI (1988)
Coolant Pump: All Technical Service Bulletins
Engine - Rattling Noise/Overheating
File In Section: 6 - Engine
Bulletin No.: 47-61-47A
Date: January, 1995
Subject:
Rattling Noise/Engine Overheating (Replace Idler Sprocket and Bearing)
Models:
1988 Buick Skylark
1987-88 Oldsmobile Calais
1988 Pontiac Grand Am
with 2.3L Engine (VIN D - RPO LD2)
Condition
Some customers may comment on a rattling noise emanating from the front cover area of the engine and/or lack of cooling capability of the engine.
Cause
The timing chain idler sprocket on some engines was manufactured without the 4 mm hole in the center of the idler sprocket assembly. This hole is
necessary for adequate lubrication at sprocket to coolant pump spline connection. Without the necessary lubrication, spline wear occurs on the sprocket
splines and possibly the splines on the coolant pump shaft.
Correction
If above conditions exist, remove timing chain front cover and inspect for 4 mm hole located directly in the center of the timing chain idler sprocket (See
Figure). If hole is not present, remove timing chain housing assembly as instructed in Service Procedure and replace idler sprocket and bearing. The
coolant pump must also be inspected for shaft spline damage and replaced if necessary.
Service Procedure
Remove or Disconnect
