Cylinder Block, Liners And Heads
The cylinders in the left side of the block form a 60 degree angle with the cylinders in the right side. The main bearing caps are fastened to the block with four bolts per cap.
The cylinder liners can be removed for replacement. The top surface of the block is the seat for the cylinder liner flange. Engine coolant flows around the liners in order to keep the liners cool. Three O-ring seals around the bottom of the liner make a seal between the liner and the cylinder block. A filler band goes under the liner flange. This makes a seal between the top of the liner and the cylinder block.
The engine has a separate cylinder head for each cylinder. Two inlet valves and two exhaust valves, which are controlled by a pushrod valve system, are used for each cylinder. Valve guides without shoulders are pressed into the cylinder heads. The opening for the unit injector is located between the four valves. A third lobe on the camshaft moves the pushrod that operates the unit injector. Fuel is injected directly into the cylinder.
There is an aluminum spacer plate between each cylinder head and the block. Coolant goes out of the block through the spacer plate and into the head through eight openings in each cylinder head face. Water seals are used in each opening to prevent coolant leakage. Gaskets seal the oil drain passages between the head, the spacer plate, and the block.
 | |
| Illustration 1 | g00316188 |
Left Side Of Engine (Typical Example) (1) Covers. (2) Covers. | |
Covers (1) allow access to the camshaft, the valve lifters, and the fuel control shaft. Covers (2) allow access to the crankshaft connecting rods, main bearings, and piston cooling jets. When the covers are removed, all the openings can be used for inspection and service.
Pistons, Rings And Connecting Rods
The aluminum pistons have an iron band for the top two rings. This band helps reduce wear on the compression ring grooves. A chamber is cast into the piston just behind the top ring grooves. Oil from the piston cooling jets flows through this chamber in order to cool the piston. The flow of oil from the piston cooling jets also improves the life of the ring. The pistons have three rings which include two compression rings and one oil ring. All the rings are located above the piston pin bore. The oil ring is a standard ring. Oil returns to the crankcase through holes in the oil ring groove. The top two rings are the Keystone rings, which are tapered. The action of the ring in the piston groove, which is also tapered, helps prevent seizure of the rings from too much carbon deposit.
The connecting rod has a taper on the pin bore end. This taper gives the rod and the piston more strength in the areas with the most load. Four bolts, which are set at a small angle, hold the rod cap to the rod. This design keeps the rod width to a minimum, so that a larger rod bearing can be used and the rod can still be removed through the liner.
Crankshaft
The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the machine. A vibration damper is used at the front of the crankshaft in order to reduce torsional vibrations (twist) that can cause damage to the engine.
The crankshaft drives a group of gears on the front and the rear of the engine. The gear group on the front of the engine drives the oil pump, the jacket water pump, the fuel transfer pump, and the accessory drives.
The rear gear group, which is also driven by the crankshaft, drives the camshafts and the accessory drives.
Seals and wear sleeves are used at both ends of the crankshaft. The seals and wear sleeves are used for easy replacement and reduction of maintenance cost. Pressure oil is supplied to all main bearings through drilled holes in the webs of the cylinder block. The oil then flows through drilled holes in the crankshaft in order to provide oil to the connecting rod bearings. The 3508 crankshaft is held in place by five main bearings. The 3512 crankshaft is held in place by seven main bearings. The 3516 crankshaft is held in place by nine main bearings. A thrust plate at either side of the center main bearing controls the end play of the crankshaft.
Camshaft
There is one camshaft per side. The 3508 camshaft is supported by five bearings. The 3512 camshaft is supported by seven bearings. The 3516 camshaft is supported by nine bearings. Each camshaft is driven by the gears at the rear of the engine.
As the camshaft turns, each lobe moves a lifter assembly. There are three lifter assemblies for each cylinder. Each outside lifter assembly moves a pushrod and two valves. The valves can be inlet valves or exhaust valves. The center lifter assembly moves a pushrod that operates the unit injector. The camshafts must be in time with the crankshaft. The relation of the camshaft lobes to the crankshaft position causes the valves and unit injectors in each cylinder to operate at the correct time.