The engine block and cylinder heads are cast iron. Turbo engines are equipped with a three-piece aluminum intake manifold and cast iron exhaust manifolds.
The oil cooling system for turbo diesel pistons provides for oil spray onto the underside of the piston crown. This is accomplished by additional oil feed orifice tubes and galleries in the block. Oil spray occurs when the piston is approaching bottom dead center on the intake and power strokes. The extra oil pressure and volume needed for piston cooling is provided by a high output oil pump. The pump has a working pressure of 80 psi (552 kPa). Oil feed for piston spray is through galleries and oil tubes located in the main bearing saddles and webs.
The crankshaft is supported by five insert style main bearings.
Thrust is taken by the number 3 main. The camshaft is also supported by five bearings; plain type bearings are used.
The engine is equipped with three ring aluminum pistons. Connecting rods are forged steel. The pistons are attached to the rods with hardened steel piston pins. Each piston pin is retained by two snap rings; one at each end of the pin. The pin is a floating fit in the rod and piston.
A single chain driven camshaft operates the overhead valve train. Roller lifters and tubular push rods actuate the rocker arms.
The arms are mounted on shafts bolted to each cylinder head.
The cylinder heads are equipped with glow plugs for each cylinder and a prechamber for each combustion chamber. One plug and one prechamber are used in each combustion chamber. The glow plugs heat air entering the prechambers. This aids the combustion process and improves cold weather starting and operation. The glow plugs are activated only when ambient temperatures fall below a preset value. On the turbo diesel engine the glow plug relay is mounted on the intake manifold and is controlled by the PCM.
The turbocharged diesel engine is equipped with a Warner Gear turbocharger. A wastegate, in the turbine housing, controls boost. The wastegate is operated by an externally mounted vacuum actuator. The actuator opens the gate to decrease boost, or closes it to increase boost. Waste gate position is controlled by the PCM.
The turbocharger increases the amount of air entering the combustion chambers. This allows a proportionate increase in fuel injected into the cylinders. The result is a much denser cylinder charge and greater power output.
The turbocharger turbine and compressor impellers are the mechanisms that pump additional air into the combustion chambers. The impeller wheels are operated by the high speed gas flow through the engine exhaust system.
Engine lubrication is through a conventional mechanical pump located at the rear of the crankcase. The pump is shaft driven by the oil pump drive unit which in turn, is driven off the camshaft. A belt driven vacuum pump is used on both engines.
Both versions of the 6.5L diesel are equipped with a high pressure fuel injection system. The system consists of an electric fuel supply pump, an injection pump, a separate injector nozzle for each cylinder, and the necessary injector feed lines.
The rotary type injection pump pressurizes, meters, and distributes fuel to the individual injectors. System working pressure is 1750 psi (120 bar) for turbocharged engines. The pump is gear driven through matching gears on the pump and camshaft.
