PISTON & ROD GP 1508238 - Caterpillar

Location of Bolts (1) and Camshaft Idler Gear Shaft (2). The effective serial numbers identified in the chart are for reference only. The preferred idler gear shafts and/or bolts may already be installed on the engine as a result of service replacement action. 3406 Machine Engines with a "70V" serial number prefix and 3406 Machine Engines built prior to serial number 11N1285 that are equipped with a 4N-0345 or 6I-0093 Idler Gear Shaft (2) require only inspection for bolt type and bolt tightening torque.
The 3G-2292 Self-Locking Bolt (1) is the preferred bolt to secure the idler gear shaft. This bolt has a locking patch and is unplated with a phosphate and oil finish. The 30-8535 Self-Locking Bolt is plated. The 0L-1351 Bolt has a phosphate and oil finish. The 30-8535 or 0L-1351 Bolts should be replaced whenever the front housing is removed.
If the engine suffers overspeed (valve train separation or damage), the front housing should be removed and the camshaft idler gear shaft retaining bolts replaced with new 3G-2292 Bolts. Tighten the bolts to a torque of 55 7 N m (41 5 lb ft).