Usage:
3406 (92U),
3406B (7FB, 8TC, 4MG, 5YG, 3ZJ1-15181, 5KJ1-7799, 2EK),
3406C (3ZJ16182-Up, 5KJ7800-Up, 4CK),
3406E (5EK) Truck Engines
Reference: Truck Engine News, October 1991, Page 5, "No Gaskets Used With Aluminum Flywheel Housings" on 3406B and 3408 Truck Engines.
Truck Engine News, September 1992, Page 1, "New Plug And O-Ring Can Prevent Oil Leakage At The Flywheel Housing Gasket" on 3406B, 3406C And 3408 Truck Engines.
Description of Change: The flywheel housing to cylinder block joint uses a gasket to improve the integrity of the joint. Additional mounting bolts, clip attachment holes, oil baffles and spotfacing under mounting bolts improve the joint reliability. A part service gasket is also available for engines without the extra mounting bolts.
Flywheel Housing Gasket
This gasket is a steel core composite design with beading between the upper bolt holes to increase gasket loading in the tongue area of the housing. The 108-5891 Gasket has 5 more (24 total bolts) 3/8 inch mounting bolt holes and requires a cylinder block and flywheel housing with comparable mounting holes. A 105-5082 Gasket (19 total bolts) is for part service to replace the 7N-9335 Gasket or the 1U-8846 Liquid Gasket on engines without the 5 additional holes in the cylinder block and flywheel housing.
Flywheel Housing
The 108-4749, 108-4750, 108-4753, and 108-4754 Flywheel Housings have:
-
- * 5 more (24 total bolts) 3/8 inch mounting bolts to provide additional clamping load on the gasket.
- * 5 tapped 3/8 inch holes for attaching clips or brackets to prevent disturbing the initial tightening torque of the mounting bolts.
- * Cast oil baffles around the camshaft and the rear main bearing area to reduce the splash oil to the upper housing area.
- * Spotfacing under all mounting bolts to assure more consistent transfer of bolt torque into bolt clamping load.
- * 5 more (24 total bolts) 3/8 inch mounting bolts to provide additional clamping load on the gasket.
Cylinder Block
The new 108-3912 Cylinder Block in 108-3916 Field Replacement Block Group for 3406B and 3406C Truck Engines and the 108-3918 Cylinder Block in 108-2111 Field Replacement Block Group for 3406E Truck Engines has 5 more (24 total bolts) 3/8 inch mounting bolt holes. These 5 mounting holes provide additional clamping load on the gasket. These cylinder blocks also have cast oil baffles around the camshaft and the rear main bearing area to reduce the splash oil to the upper housing area.
Adaptable To: 3406B and 3406C Truck Engines 2EK901-UP, 3ZJ6200-49090, 4CK168-24018, 5KJ7584-8008 and 3406E Truck Engines 5EK1-1384 were built with 1U-8846 sealant and may be serviced with the 105-5082 Flywheel Housing Gasket.
Truck Engines built with 108-5891 Flywheel Housing Gasket between the flywheel housing and cylinder block should be serviced with that gasket.
These improvements were phased in over several months. Engines are built with castings changed but bosses not machined. Therefore, engines may have bosses machined or not machined on the cylinder block and a flywheel housing with no bosses or bosses not machined. Conversely, there may be engines with no cylinder block bosses but the flywheel housing with bosses not machined.
The 108-3912 Cylinder Block is effective with 3406C Truck Engines 3ZJ48667, 4CK23678, 5KJ8009. The 108-3918 Cylinder Block is effective with 3406E Truck Engine 5EK01368.
The 108-5891 Flywheel Housing Gasket and 108-4749, 108-4750, 108-4753, and 108-4754 Flywheel Housings are effective with 3406C Truck Engines 3ZJ49091, 4CK24019, 5KJ8009 and 3406E Truck Engine 5EK01385.
Repair Procedure
Before installing the gasket, existing sealant must be removed from the mating surfaces of the flywheel housing and cylinder block with 4C-4188 Paint Remover. Do not use a steel brush or rotary "Scotch Brite" pad to clean the surfaces. These may damage the contact surfaces. The previous gasket extended below the pan mounting surface and filled the entire block to flywheel housing joint. The 108-5891 and 105-5082 Flywheel Housing Gaskets with the steel core cannot be trimmed after assembly and is flush to recessed at the "Tee" joint between the block, flywheel housing, and oil pan. Seal the area not occupied with gasket material with 8T-9022 RTV Sealant (BLUE). This sealant is compatible with the gasket material. Using the 105-5082 Flywheel Housing Gasket on a flywheel housing originally designed for use with sealant may require elongation of the bolt holes in the pan, oil pan gasket, and stiffener plate (if equipped). The gasket is approximately 0.76 mm (.030 in) thick. Before engine operation, check the clearance between the flywheel housing and rear gear train and flywheel. Push the crankshaft towards the front of the engine when checking the flywheel to flywheel housing clearance. Flywheel housings designed for gaskets have a 16.76 mm (.660 in) dimension from the flywheel housing to the centerline of the oil pan mounting bolts. Flywheel housings designed for sealant have a 17.46 mm (0.688 in) dimension from the flywheel housing mounting face to the centerline of the oil pan mounting bolts. These housings are usually marked with the note "CAUTION: USE ONLY LIQUID GASKET ON BLOCK JOINT" on the inside of the housing
Illustration 1. Bolt Tightening Procedure For "19 Bolt" Flywheel Housings
Bolt identification for "19 Bolt" flywheel housings.
Tighten bolts 1 through 19 in numerical sequence to a torque of 40 ± 10 N·m (30 ± 7 lb ft).
Tighten bolts 1 through 9 in numerical sequence to a torque of 135 ± 20 N·m (100 ± 15 lb ft).
Tighten bolts 10 through 19 in numerical sequence to a torque of 55 ± 10 N·m (40 ± 7 lb ft).
Bolt Tightening Procedure For "24 Bolt" Flywheel Housings
Illustration 2. Bolt identification for "24 Bolt" flywheel housings.
Tighten bolts 1 through 24 in numerical sequence to a torque of 40 ± 10 N·m (30 ± 7 lb ft).
Tighten bolts 1 through 9 in numerical sequence to a torque of 135 ± 20 N·m (100 ± 15 lb ft).
Tighten bolts 10 through 24 in numerical sequence to a torque of 55 ± 10 N·m (40 ± 7 lb ft).