The 2.0 litre DOHC (Double OverHead Camshaft) engine was introduced in August 1989 to replace the 2.0 litre SOHC engine used previously in the Sierra range. The engine is of four-cylinder, in-line type.

The crankshaft incorporates five main bearings. Thrustwashers are fitted to the centre main bearing in order to control crankshaft endfloat.

The camshafts are driven by a chain from the crankshaft, and operate the angled valves via hydraulic cam followers. One camshaft operates the inlet valves, and the other operates the exhaust valves. The operation of the cam followers is explained in Chapter 2, Part C, but note that no rollers are fitted and the base of each cam follower is in direct contact with the cam profile.

The distributor is driven directly from the front of the inlet camshaft, and the oil pump is driven by a chain from the crankshaft. An electric fuel pump is mounted in the fuel tank.

Lubrication is by means of a bi-rotor pump which draws oil through a strainer located inside the sump, and forces it through a fullflow filter into the engine oil galleries, from where it is distributed to the crankshaft and camshafts. The big-end bearings are supplied with oil via internal drillings in the crankshaft.

The undersides of the pistons are supplied with oil from drillings in the connecting rods.

The hydraulic cam followers are supplied with oil from passages in the cylinder head. The camshafts are lubricated by oil from spray tubes mounted above the camshaft bearing caps.

A closed crankcase ventilation system is employed, whereby piston blow-by gases are drawn from the crankcase, through a breather pipe into the inlet manifold, where they are burnt with fresh air/fuel mixture.

Crankcase ventilation system - inspection and maintenance

Refer to Chapter 1, Section 35.

Major operations possible with the engine in the vehicle

The following operations can be carried out without removing the engine from the vehicle: a) Removal of the camshafts.

b) Removal and servicing of the cylinder head c) Removal of the timing chain and sprockets.

d) Removal of the oil pump.

e) Removal of the sump.

f) Removal of the pistons and connecting rods.

g) Removal of the big-end bearings.

h) Removal of the engine mountings i) Removal of the clutch and flywheel.

j) Removal of the crankshaft front and rear oil seals.

Major operations requiring engine removal

The following operation can only be carried out after removing the engine from the vehicle: a) Removal of the crankshaft and main bearings.