3B7Q84366-0 Tohatsu REAR PANEL

Illustration 1 g01871934
Cylinder block and components for the lower end of the engine
(1) Cylinder block
(2) Piston cooling jet
(3) Crankcase covers
(4) Crankshaft
(5) Main bearing cap
(6) Saddle bolts for the main bearing cap
(7) Main bearing studs The cylinders for this engine are positioned at a 30 degree angle from the vertical centerline of cylinder block (1).Piston cooling jets (2) are mounted to the cylinder block. The oil spray from the jets is used to provide lubrication to the piston. The oil spray is also used to cool the piston rings. Crankcase covers (3) allow access to the connecting rods, to the main bearings, and to the piston cooling jets. When the covers are removed, all of the openings can be used for inspection and for service. Main bearing caps (5) are used to secure crankshaft (4) into the cylinder block. Saddle bolts (6) are used to horizontally secure the main bearing caps. The main bearing caps are fastened vertically to the cylinder block with main bearing studs (7). A hydraulic tensioning tool must be used to tighten the main bearing studs during installation.Cylinder Liners
Illustration 2 g01873520
Components for the cylinder pack
(A) Machined counterbore surface for the sleeve
(B) Machined grooves for the O-ring seals
(C) Liner flange
(8) O-ring seals
(9) Cylinder liner
(10) Sleeve
(11) Piston rings
(12) Piston
(13) Connecting rod
(14) Piston pin For this engine, the cylinder is serviceable as a parts kit. Three O-ring seals (8) are used to create a seal between the cylinder liner (9) and the cylinder block. There are machined grooves (B) in the outer wall of the liner that accommodate each O-ring seal. Engine coolant flows around the cylinder liners in order to dissipate heat that is created in the combustion chamber during combustion. These O-ring seals are used to provide a seal around the cooling jacket. Sleeve (10) fits into machined counterbore surface (A) that is at the top of the cylinder liner. During engine operation, the sleeve scrapes the area of the piston that is above the top piston ring in order to remove carbon buildup. This action prevents polishing of the cylinder wall. The cylinder liner is a midsupported design. The support for the liner flange (C) is located below the top deck of the engine block.The engines cylinder pack consists of the piston, piston rings, piston pin, piston rod, and cylinder liner.Piston rings (11) are installed in the ring grooves that are located in the top portion of piston (12). The piston rings fit tightly inside the cylinder. The two top rings seal the combustion chamber as the piston moves in the cylinder. The bottom ring scrapes the oil from the cylinder liner. The piston is attached to the small end of connecting rod (13). Piston pin (14) is used to create an articulated joint between the piston and the connecting rod. Six bolts are used to secure the large end of the connecting rod around the bearing journal on the crankshaft. In order to create the cap of the connecting rod, the rod is fractured along the centerline of the radius of the connecting rods large end.Note: The large end of the connecting rod cannot be removed through the cylinder liner. The piston, rod, and the liner must be removed from the block as a group. The piston and rod assembly can then be removed from the bottom end of the liner.Cylinder Heads
Illustration 3 g01871414
Components for the cylinder pack
(15) Valve mechanism cover
(16) Cylinder head
(17) Valve guide bushings
(18) Valve seat inserts
(19) Integral seal
(20) Combustion gasket Valve mechanism cover (15) is bolted to cylinder head (16). A rubber gasket is installed in order to seal the cover to the head. Remove the valve mechanism cover in order to service the injector and the valve train components. Valve guide bushings (17) are mechanically pressed into the cylinder heads. Also, the valve seat inserts (18) are mechanically pressed into the cylinder heads. There are valve seats for two inlet valves and two exhaust valves that are for each cylinder. Integral seal (19) and combustion gasket (20) are used to seal the cylinder head to the cylinder block and to the liner. The integral seal is used to seal coolant passages and oil passages that transfer fluids between the cylinder block and the cylinder head. The combustion gasket seals the combustion gases that are in the combustion chamber.