Usage:
3116 (7SF) Truck Engines
Description of Change: A new shim is used in the governor. During normal use at operating temperature, an audible rpm surge may be present at low engine rpm. The new shim brings the governor high idle spring into contact with the spring seat at lower rpm. This improves the low idle stability of the engine.
Adaptable To: The new 4P5605 Shim is effective with governor serial number 0034377, engine serial number 7SF15340. The new shim is adaptable to earlier truck engines. Use the following procedure to install the shim(s).
Procedure To Install 4P5605 Shim
NOTE: DO NOT remove the governor. This procedure can be done easily with the governor on the engine and requires approximately 0.5 hours labor.
1. Remove three socket head bolts (2) securing rear cover assembly (3) to the rear governor housing. See illustration.
2. Carefully remove rear cover (3), shims (4), and governor spring seat (5) as an assembly.
NOTE: DO NOT remove the governor springs, DO NOT disturb existing shims (4).
3. Install one 4P5605 Shim (1) on the spring side of spring seat (5). See illustration.
4. Install spring seat (5), shims (4) and rear cover assembly (2). Make certain dashpot piston (6), low idle spring (7) and high idle spring (8) are correctly positioned. Tighten the three socket head bolts (2) to a torque of 2.2 ± 0.2 N·m (20 ± 2 lb in).
5. Bring the engine to operating temperature.
6. Use a 1U7771 Phototach or 6V3121 Multitach and set low idle to 750 ± 10 rpm.
NOTE: DO NOT use the instrument panel tachometer to set low or high idle.
7. Evaluate for improvement in surge condition. If satisfactory, proceed to Step 8.
If low idle instability has been reduced, but not satisfactorily, shut off the engine and add a second shim.
NOTE: DO NOT add more shims than is necessary to improve the stability. A MAXIMUM of three shims may be installed.
8. When completed, reset the high idle to the "Bare Engine High Idle" specification printed on the Engine Identification Plate, located on the valve cover. Install a new lockwire and dealer seal on the high idle adjusting screw.
Location of new shim and corresponding components.