GEAR 2986977 - Caterpillar

Illustration 1. The new valve stem seal assemblies with the new spring retainers now used on the inlet and exhaust valves.The former seal formed only an "umbrella" over the end of the valve stem guide. The former seal was not retained and thus it could slide up and down with the valve and become ineffective. The new seal seats directly on the head, and is held in this position by the force of the valve spring.
As an interim change, the new spring retainer was used with the FORMER seal. Since the new retainer was designed for use with the new seal that has a flange under the spring, a 9Y7355 Seat (Spacer) is required to maintain the same compressed spring length on these interim engines. See Illustration 2.
Illustration 2. The interim change where the new retainers are used with the separate spring seats on both valves, but the former seal was still used only on the inlet valve as shown.Adaptable To: The new spring retainers and the interim 9Y7355 Seats are effective with: (interim engines) 3114 Ind. Engine: 5EF482, 1ZG (not available)3114 Standby Generator Set Engine: 6AF4703114 Generator Set Engine: 5JG4733116 Ind. Engine: 2WG546, 4PG (not available)3116 Standby Generator Set Engine: 2SG6433116 Generator Set Engine: 1NJ5763114, 3116 Cat Vehicular Engines (not available) The new seals are effective with:
3114 Ind. Engine: 5EF617, 1ZG (not available)3114 Standby Generator Set Engine: 6AF5283114 Generator Set Engine: 5JG6453116 Ind. Engine: 2WG766, 4PG (not available)3116 Standby Generator Set Engine: 2SG7813116 Generator Set Engine: 1NJ7903114, 3116 Cat Vehicular Engines (not available)On the interim engines, the new 9Y8847 Seal Assembly can be installed in place of the former 7C7448 Seal and the 9Y7355 Seat. Do not use the seat if the new seal is used. The new 9Y7356 Retainers already on these engines can be reused.
For the earlier engines that are using both the former retainer and former seal, replace these parts with the new 9Y7356 Retainers and new 9Y8847 Seal Assemblies. See Illustration 1. Do not use the 9Y7355 Seat.
Installing The New Seals
The seals can be installed with the head on the engine, and with the fuel injectors installed, by using a special plate to compress the springs. Make this plate as shown in Illustration 3. Use mild steel plate, 6.0 mm (.25") thick.
Illustration 3. Dimensions of spring compressor plate.Also needed are three threaded rods. They should be about 153 mm (6.0") long with 8 mm threads (M8 by 1.25).
To prevent the valves from falling inside the cylinders, the pistons should be at TDC (Top Dead Center). For 3114 Engines, this means pistons 1 and 4 are at TDC when the 8T0100 Bolt engages the timing hole in the flywheel through the flywheel housing. Turning the crankshaft 180° counterclockwise (CCW) moves pistons 3 and 4 to TDC.
For 3116 Engines, pistons 1 and 6 are at TDC when the 8T0100 Bolt engages the timing hole. Turning the crankshaft 120° CCW moves pistons 2 and 5 to TDC, and another 120° moves 3 and 4 to TDC.
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