Jeep Cherokee

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Engine » 4.0L engine » Description and operation
Engine

DESCRIPTION

The 4.0 Liter (242 CID) six-cylinder engine is an In-line, lightweight, overhead valve engine.

This engine is designed for unleaded fuel. The engine cylinder head has dual quench-type combustion chambers that create turbulence and fast burning of the air/fuel mixture. This results in good fuel economy.

The cylinders are numbered 1 through 6 from front to rear. The firing order is 1-5-3-6-2-4 (Fig. 1).

Fig. 1 Engine Firing Order

The crankshaft rotation is clockwise, when viewed from the front of the engine. The crankshaft rotates within seven main bearings. The camshaft rotates within four bearings.

BUILD DATE CODE

The engine Build Date Code is located on a machined surface on the right side of the cylinder block between the No.2 and No.3 cylinders (Fig. 2).

The digits of the code identify:

•  1st Digit-The year (8 = 1998).
•  2nd & 3rd Digits-The month (01 - 12).
•  4th & 5th Digits-The engine type/fuel system/ compression ratio (MX = A 4.0 Liter (242 CID) 8.7:1 compression ratio engine with a multi-point fuel injection system).
•  6th & 7th Digits-The day of engine build (01 - 31).

(1) FOR EXAMPLE: Code * 801MX12 * identifies a 4.0 Liter (242 CID) engine with a multi-point fuel injection system, 8.7:1 compression ratio and built on January 12, 1998.

Fig. 2 Build Date Code Location

1 - YEAR
2 - MONTH
3 - DAY

Engine

Lubrication system

Cylinder block

Cylinder head

Crankshaft

Piston and connecting rod

Camshaft

Rocker ARM

Valves

Cylinder head cover

Hydraulic tappet

Valve stem seal

Exhaust manifold