Usage:
3408C (48W),
3408E 99C),
3412C (73W),
3412E (80M) Machine Engines In Caterpillar Machines
- SUPPLEMENT: MARCH 16, 1998
Service Magazine SEPD0404, Article 25, Page 33; "Be Sure To Use The Correct Inlet And Exhaust Valve Bridges That Do Not Ride On Dowels".
Please add the following Note to the bottom of the right hand column on Page 33:
NOTE: The 3408E (99C) and 3412E (80M) Machine Engines also have valve mechanism groups that include valve bridges that do not ride on dowels.
--------------- END SUPPLEMENT ---------------
Effective with 3408C (48W41034) and 3412C (73W18062) Machine Engines, the valve mechanism groups include valve bridges that do not ride on dowels. See Illustration 1. Formerly, valve bridges that rode on dowels were used. See Illustration 2. At the same time the valve bridges that do not ride on dowels became effective, new longer inlet and exhaust valves became effective. The distance from the top retainer groove to the top of the valve stem is 3.0 mm (.12 in) longer on the new 122-0321 Exhaust Valve and new 122-0322 Inlet Valve than on the 115-2367 Exhaust Valve and 115-2368 Inlet Valve. See Illustrations 3 and 4.
NOTE: Install a 122-0321 Exhaust Valve or 122-0322 Inlet Valves on 3408C or 3412C Machine Engine with a serial number higher than 48W41033 or 73W18061 respectively. For earlier engines, use 115-2367 Exhaust Valves and 115-2368 Inlet Valves.
Illustration 1.
Typical valve mechanism with valve bridges that do not ride dowels. The arrow identifies the valve bridge.
Illustration 2.
Typical valve mechanism with a valve bridge that rides on a dowel. The arrow identifies the valve bridge.
Illustration 3.
122-0321 Exhaust Valve or 122-0322 Inlet Valve. (X) = 15.45 mm (.608 in).
Illustration 4.
115-2367 Exhaust Valve and 115-2368 Inlet Valve. (Y) = 12.45 mm (.490 in).