Usage:
3406B (2EK1-Up, 5KJ1-Up),
3406C (3ZJ1-32590, 4CK1-9548) Truck Engines
The heating process used to install the camshaft drive gear onto the camshaft could allow a small reduction in gear tooth hardness. This reduction in hardness could result in gear tooth chipping at high mileage/hours.
The camshaft drive gear should be inspected during the Overhaul Protection Plan For Trucks (OPT) preinspection and/or at overhaul. This will help prevent the progression of any existing tooth damage. The outer edge of the camshaft drive gear can be inspected without removing the timing gear housing or the camshaft from the engine. The cover for the timing advance unit can be removed. (See the appropriate Disassembly And Assembly Manual.) When the cover is removed, the lower right hand portion of the camshaft drive gear is visible. The outer edge of the camshaft drive gear, where it mates with the fuel pump (timing advance) drive gear, can be seen. Mark the camshaft drive gear and slowly rotate the engine. Inspect each tooth of the camshaft drive gear until the camshaft drive gear has rotated 360 degrees. Inspect each tooth for visible cracks and chipping (spalling). Replace the camshaft assembly if necessary. See Gear Reusability Guideline, SEBF8045 for more information.