Engine: Description and Operation

DESCRIPTION
The 4.6L (281 CID) engine is an 8 cylinder "V" gasoline engine. It is of the overhead cam design (OHC) and operates on unleaded fuel. This is NOT a free-wheeling engine, it is an interference type engine. If it has jumped time, there will be damage to the valves and pistons (6108) and will require the removal of the cylinder heads.

AIR/FUEL SYSTEM
The fuel/air mixture needed for burning in the cylinders is provided by sequential multiport fuel injection (SFI). This fuel induction system is mounted on an aluminum intake manifold which in turn is bolted to cast iron cylinder heads. Refer to Powertrain Management for information on the SFI system and air induction components.

CYLINDER HEAD
The cylinder heads (6049) are aluminum. They house the single overhead camshafts (6250) (SOHC) and there are two valves per cylinder.

CYLINDER BLOCK
The cylinder block is a 90° V design and cast iron.

INTAKE MANIFOLD
The intake manifold (9424) is a center entry composite intake manifold.

OIL PUMP
The oil pump is a positive displacement, internal gear pump using top seal rotors. It is mounted on the front face of the cylinder block. System pressure is limited by an integral, internally vented relief valve which directs the bypass oil back to the inlet side of the oil pump.

POSITIVE CRANKCASE VENTILATION (PCV)
This engine incorporates a closed-type positive crankcase ventilation (PCV) system and exhaust emission control system. All engine/emission control systems are covered in Powertrain Management. To maintain the required exhaust emission levels, the fuel system, ignition system, and engine must be kept in good operating condition and meet recommended adjustment specifications.

SERVICING
When performing tests, adjustments or service to the engine, ignition system or fuel system, it is essential to follow the proper procedures and specifications. Refer to the proper component or system. Refer to Powertrain Management for emission control or computer control information. Make sure that the following engine components are not serviceable before replacing damaged or worn engine components:
- crankshaft.
- cylinder heads
- valve guides
- exhaust valves.
- intake valve.
- camshafts.
- cylinder block.

TRANSMISSION
Available with an automatic transmission.

VALVE TRAIN
The single overhead camshafts (6250) (SOHC) open the valves. There are two valves per cylinder.