13290 - Service Update. An analysis of engine build data revealed that there could be a build concern that could cause drivability issues with the engines originally installed in these vehicles. To ensure the highest quality and best ownership experience for our customers, these engines need to be replaced prior to vehicle delivery. This bulletin provides a service procedure to inspect and, if necessary, replace the engine assembly on certain vehicles equipped with a 5.3L V8 engine (RPO L83) or a 4.3L V6 engine (RPO LV3). These vehicles may have been assembled with bent piston oil squirters. If the squirter is bent out-of-position, the connecting rod may hit the squirter during engine operation, creating a high frequency noise. The knock sensor may respond to that noise, retarding spark, impairing engine performance and transmission shift quality.
