Engine - Overview

Overview 

The 6.8L (3V) is a V-10 engine with the following features:

• Single overhead camshafts
• Three valves per cylinder
• SFI
• Aluminum cylinder heads
• Cast iron, 90-degree V-cylinder block
• Individually chain-driven camshafts with a hydraulic timing chain tensioner on each timing chain

Engine Identification 

Always refer to these labels when installation of new parts is necessary or when checking engine calibrations. The engine parts often differ within a CID (cubic inch displacement) family. Verification of the identification codes will make sure the correct parts are obtained. These codes contain all the pertinent information relating to the dates, optional equipment and revisions.

Engine Code Information Labels 

The engine code information label is located on the crankcase ventilation housing and contains the following:

Courtesy of FORD MOTOR COMPANY

Engine Cylinder Identification 

Courtesy of FORD MOTOR COMPANY

Valve Train 

The valve train operates as follows:

• Ball-tip hydraulic lash adjusters provide automatic lash adjustment.
• Roller followers ride on the camshaft lobe, transferring the up-and-down motion of the camshafts to the valves in the cylinder heads.

Lubrication System 

The engine lubrication system operates as follows:

• Oil is drawn into the oil pump through the oil pump screen cover and tube in the sump of the oil pan.
• Oil is pumped through the oil filter on the left front side of the cylinder block.
• Oil enters the main gallery where it is distributed to the crankshaft main journals and to the cylinder heads.
• From the main journals, the oil is routed through cross-drilled passages in the crankshaft to lubricate the connecting rod bearings. Controlled leakage through the crankshaft main bearings and connecting rod bearings is slung radially outward to cool and lubricate the cylinder walls as well as the entire connecting rod, piston and piston ring assembly.
• The left cylinder head is fed from a drilling into the supply passage feeding the main gallery at the front of the cylinder block. The right cylinder head is fed from a drilling into the rear of the main gallery. Main gallery pressure is reduced through fixed serviceable orifices as it enters the valve block bolted to the front of the cylinder head. It is this reduced pressure in the cylinder head galleries which feeds the camshaft journals and lash adjusters.
• The camshaft lobe and roller followers are lubricated by splash created through valve train operation.

Oil Pump 

The lubrication system of the 6.8L (3V) engine is designed to provide optimum oil flow to critical components of the engine through its entire operating range. The heart of the system is a positive displacement internal gear oil pump using top seal rotors. Generically this design is known as a gerotor pump, which operates as follows:

• The oil pump is mounted on the front face of the cylinder block.
• The inner rotor is piloted on the crankshaft post and is driven through flats on the crankshaft.
• System pressure is limited by an integral, internally-vented relief valve which directs the bypassed oil back to the inlet side of the oil pump.
• Oil pump displacement has been selected to provide adequate volume to make sure of correct oil pressure, both at hot idle and maximum speed.
• The relief valve calibration protects the system from excessive pressure during high viscosity conditions.
• The relief valve is designed to provide adequate connecting rod bearing lubrication under high- temperature and high-speed conditions.