The 6.2L Diesel engine features overhead valves & stainless steel swirl pre-chambers. It is an over square design; that is the bore is larger than the stroke. This provides higher RPM for heavy duty usage. The 6.2L is built in 2 versions. The LH6 Lt-duty is for use in 6,000-8,500 GVW Lt. Duty trucks and has 46mm diameter intake valves and 42mm diameter exhaust valves. The LL4 Heavy duty version is for use in trucks in the 8500-10,000 GVW range and has 50mm diameter intake valves and 42mm diameter exhaust valves in 1982 and 1983. The 1984 and later LL4 versions will use 46mm diameter intake valves and 38mm diameter exhaust valves. The 1985 Calif. LH6 uses 46mm intake and 39mm exhaust valves. The firing order is 1-8-7-2-6-5-4-3 and #1 cylinder is left bank forward.
Cylinders #1, 3, 5, 7 are on the left bank and cylinders #2, 4, 6, 8 are on the right bank.
This engine is similar to a V-8 gasoline engine in many ways but major differences occur in the cylinder heads, combustion chamber, fuel distribution system, air intake manifold and the method of ignition. The cylinder case, crankshaft, main bearings, rods, pistons and wrist pins are a heavy duty design, because of the high compression ratio required in the diesel engine to ignite fuel. Ignition of the fuel in a diesel engine occurs because of heat developed in the combustion chamber during the compression stroke. Thus, no spark plugs or high voltage ignition are necessary for a diesel engine.
Intake and exhaust valves in the cylinder heads operate the same as in a gasoline engine but are of special design and material for diesel operation. The special alloy steel pre-chamber inserts in the cylinder head combustion chambers are serviced separately from the head. With the cylinder head removed, they can be pushed out after removing the glow plugs and injection nozzles. Glow plugs and injector nozzles are threaded for assembly into the head. The nozzles are spring loaded and calibrated to open at a specified p.s.i. of fuel pressure.
Because the intake manifold is always open to atmospheric pressure, there is no vacuum supply and a vacuum pump is required to operate accessories such as air conditioning, door diaphragms and cruise control.
The engine is designed with a 101mm (3.98 inch) bore and a 97mm (3.8 inch) stroke, which produces 6217 CC (379.4 cubic inches). The compression ratio is 21.5 to 1. The cylinder head incorporates a 17 bolt head design which locates 5 bolts around each cylinder. This helps gasket durability, by increasing clamping load.
The cylinder head includes a high swirl pre-combustion chamber which mixes fuel and air to provide an efficient fuel burn and low emissions. A glow plug is used to assist in starting this system. A special cavity in the piston top further assists in mixing the combustion products for complete burning.
The main bearing caps all use 4 bolts to provide a rigid support for the crankshaft and minimize stress.
The rolled fillet nodular iron crankshaft utilizes a torsional damper, tuned to reduce vibrations.
This engine uses roller hydraulic valve lifters running on a forged steel camshaft.
The fuel system includes a water sensor, which signals high water levels and a need for service. Additional water separation, and a drain valve is provided at the filter.
A block heater is standard equipment to aid starting in severe weather.
