SLIP JOINT GP 3904797 - Caterpillar

All 3304, 3306 Industrial, Marine, Generator Set Engines, Excluding Natural Gas EnginesThe rotocoil assembly (valve rotator) used in the above engines is made of a rotocoil assembly and an oil shield. To give acceptable oil control, both the oil shield and the rotocoil assembly must be installed together as a unit; the shield fits into the bottom of the rotocoil assembly.
There have been reports from the field that some servicemen have installed these components separately. The oil shields were installed below the valve springs while the rotocoil assemblies were installed above the springs. The result was a loss of oil control.
Make a reference to this article next to the installation procedure for valves in the Service Manuals for the above engines.