Engine: Description and Operation

GENERAL DESCRIPTION

ENGINE IDENTIFICATION

The 3100 engine may be identified by the code letter M in the eighth digit location of the vehicle identification number.

ENGINE CONSTRUCTION

Cylinder Block

The cylinder block is made of cast alloy iron and has six cylinders arranged in a "V" shape with three cylinders in each bank. The cylinder banks are set at a 60 degree angle from each other.

The right bank cylinders (1,3,5) are on the cowl side of the engine compartment, and the left bank cylinders (2,4,6) are on the front side of the vehicle.

Four main bearings support the crankshaft which is retained by bearing caps that are machined with the block for proper alignment and clearances. The main bearing caps are also drilled and tapped for the structural oil pan side bolts.

Cylinder Head

The aluminum cylinder heads have individual intake and exhaust ports for each cylinder. Valve guides are pressed, and rocker arms are located on a pedestal in a slot in the cylinder head and are retained on individual threaded bolts.

Crankshaft and Bearings

The crankshaft is cast nodular iron with deep rolled fillets on all six crankpins and all four main journals. Four steel-backed aluminum bearings are used, with the #3 bearing being the end-thrust bearing.

Camshaft and Drive

The camshaft is made from a new metal composite design. The camshaft profile is a hydraulic roller design. The camshaft is supported by four journals and includes an oil pump drive gear.

Pistons and Connecting Rods

The pistons are cast aluminum using two compression rings and one oil control ring. The piston pin is offset 0.8 mm (0.031 inch) towards the major thrust side. This allows a gradual change in thrust pressure against the cylinder wall as the piston travels its path. Pins are chromium steel and have a floating fit in the pistons. They are retained in the connecting rods by a press fit.

Connecting rods are made of forged steel. Full pressure lubrication is directed to the connecting rods by drilled oil passages from the adjacent main bearing journal.

Valve Train

A roller rocker type valve train is used. Motion is transmitted from the camshaft through the hydraulic roller lifter and pushrod to the roller rocker arm. The rocker arm pivots on needle roller bearings and transmits the camshaft motion to the valve. The rocker arm pedestal locates in a slot in the cylinder head and the rocker arm is retained in the cylinder head by a bolt. The pushrod is located by the rocker arm.

Intake Manifold

The intake manifold is a two-piece cast aluminum unit. It centrally supports a fuel rail with six fuel injectors.

Exhaust Manifolds

The exhaust manifolds are cast nodular iron.

ENGINE LUBRICATION

Full pressure lubrication, through a full flow oil filter is furnished by a gear type oil pump. Oil is drawn up through the pickup screen and tube, and passed through the pump to the oil filter.

The oil filter is a full flow paper element unit. An oil filter bypass is used to ensure adequate oil supply 9n cold start or should the filter become plugged or develop excessive pressure drop. The bypass is designed to open at 69-83 kpa (10-12 psi).

A new priority oil delivery system supplies oil first to the crankshaft journals. Oil from the crankshaft main bearings is supplied to the connecting rod bearings by means of intersecting passages drilled in the crankshaft. The passages supplying 6i1 to the camshaft bearings also supply oil to the crankshaft main bearings through intersecting vertical drilled holes. Oil passages from the camshaft journals supply oil to the hydraulic lifters.

The hydraulic lifters pump oil up through the pushrods to the rocker arms. Oil draining back from the rocker arms is directed by cast dams in the crankcase casting to supply the camshaft lobes. The camshaft chain drive is lubricated by indirect oil splash.