All about Ford Mondeo

General information
In-car engine repair procedures / General information

How to use this Chapter This Part of Chapter 2 is devoted to repair procedures possible while the engine is still installed in the vehicle, and includes only the Specifications relevant to those procedures.

Since these procedures are based on the assumption that the engine is installed in the vehicle, if the engine has been removed from the vehicle and mounted on a stand, some of the preliminary dismantling steps outlined will not apply.

Information concerning engine/transmission removal and refitting, and engine overhaul, can be found in Part B of this Chapter, which also includes the Specifications relevant to those procedures.

General description - engine The engine, also known by Fords internal code name Zetec (formerly Zeta), is of four-cylinder, in-line type, mounted transversely at the front of the vehicle, with the (clutch and) transmission on its left-hand end (see illustrations).

1.3A Longitudinal cross-section through engine - inset showing timing belt
1.3A Longitudinal cross-section through engine - inset showing timing belt details

1 Inlet camshaft
2 Exhaust camshaft
3 Oil galleries
4 Exhaust port
5 Oil strainer and pick-up pipe 6 Oil baffle
7 Crankshaft
8 Piston-cooling oil jet (where fitted) 9 Inlet valve
10 Inlet port
11 Fuel injector
12 Inlet camshaft toothed pulley 13 Timing belt
14 Exhaust camshaft toothed pulley 15 Timing belt (front) guide pulley 16 Crankshaft toothed pulley - behind 17 Crankshaft pulley
18 Oil cooler (where fitted) 19 Timing belt (rear) guide pulley 20 Timing belt tensioner

1.3B Lateral cross-section through engine
1.3B Lateral cross-section through engine

1 Exhaust valve
2 Piston
3 Oil baffle
4 Oil strainer and pick-up pipe 5 Spark plug
6 Fuel injector
7 Piston-cooling oil jets (where fitted)

Apart from the plastic timing belt covers and the cast-iron cylinder block/crankcase, all major engine castings are of aluminium alloy.

The crankshaft runs in five main bearings, the centre main bearings upper half incorporating thrustwashers to control crankshaft endfloat. The connecting rods rotate on horizontally-split bearing shells at their big-ends. The pistons are attached to the connecting rods by gudgeon pins which are an interference fit in the connecting rod small-end eyes. The aluminium alloy pistons are fitted with three piston rings: two compression rings and an oil control ring. After manufacture, the cylinder bores and piston skirts are measured and classified into three grades, which must be carefully matched together, to ensure the correct piston/cylinder clearance; no oversizes are available to permit reboring.

The inlet and exhaust valves are each closed by coil springs; they operate in guides which are shrink-fitted into the cylinder head, as are the valve seat inserts.

Both camshafts are driven by the same toothed timing belt, each operating eight valves via self-adjusting hydraulic tappets, thus eliminating the need for routine checking and adjustment of the valve clearances. Each camshaft rotates in five bearings that are linebored directly in the cylinder head and the (bolted-on) bearing caps; this means that the bearing caps are not available separately from the cylinder head, and must not be interchanged with caps from another engine.

The water pump is bolted to the right-hand end of the cylinder block, inboard of the timing belt, and is driven with the power steering pump and alternator by a flat polyvee-type auxiliary drivebelt from the crankshaft pulley.

When working on this engine, note that Torx-type (both male and female heads) and hexagon socket (Allen head) fasteners are widely used; a good selection of bits, with the necessary adaptors, will be required, so that these can be unscrewed without damage and, on reassembly, tightened to the torque wrench settings specified.

General description - lubrication system
Lubrication is by means of an eccentricrotor trochoidal pump, which is mounted on the crankshaft right-hand end, and draws oil through a strainer located in the sump. The pump forces oil through an externallymounted full-flow cartridge-type filter - on some versions of the engine, an oil cooler is fitted to the oil filter mounting, so that clean oil entering the engines galleries is cooled by the main engine cooling system. From the filter, the oil is pumped into a main gallery in the cylinder block/crankcase, from where it is distributed to the crankshaft (main bearings) and cylinder head (see illustration).

1.10 Engine lubrication system - inset showing longitudinal cross-section
1.10 Engine lubrication system - inset showing longitudinal cross-section

1 Main oil gallery
2 From oil filter
3 Oil pump
4 Cylinder head oil-retaining valve 5 Cylinder head oil gallery 6 Cylinder head oil supply 7 Oil return
8 Piston-cooling oil spray (where fitted) 9 Oil filter - oil cooler not shown here

The big-end bearings are supplied with oil via internal drillings in the crankshaft. On some versions of the engine, each piston crown is cooled by a spray of oil directed at its underside by a jet. These jets are fed by passages off the crankshaft oil supply galleries, with spring-loaded valves to ensure that the jets open only when there is sufficient pressure to guarantee a good oil supply to the rest of the engine components; where the jets are not fitted, separate blanking plugs are provided, so that the passages are sealed, but can be cleaned at overhaul (see illustration).

1.11 Piston-cooling oil jet details
1.11 Piston-cooling oil jet details

1 Oil jets (when fitted) 2 Oil flow - only when valve opens at set pressure 3 Oil spray
4 Blanking plug (when fitted)

The cylinder head is provided with two oil galleries, one on the inlet side and one on the exhaust, to ensure constant oil supply to the camshaft bearings and hydraulic tappets. A retaining valve (inserted into the cylinder heads top surface, in the middle, on the inlet side) prevents these galleries from being drained when the engine is switched off. The valve incorporates a ventilation hole in its upper end, to allow air bubbles to escape from the system when the engine is restarted.

While the crankshaft and camshaft bearings and the hydraulic tappets receive a pressurised supply, the camshaft lobes and valves are lubricated by splash, as are all other engine components.

Valve clearances - general It is necessary for a clearance to exist between the tip of each valve stem and the valve operating mechanism, to allow for the expansion of the various components as the engine reaches normal operating temperature.

On most older engine designs, this meant that the valve clearances (also known as tappet clearances) had to be checked and adjusted regularly. If the clearances were allowed to be too slack, the engine would be very noisy, its power output would suffer, and its fuel consumption would increase. If the clearances were allowed to be too tight, the engines power output would be reduced, and the valves and their seats could be severely damaged.

The engines covered in this manual, however, employ hydraulic tappets which use the lubricating systems oil pressure automatically to take up the clearance between each camshaft lobe and its respective valve stem. Therefore, there is no need for regular checking and adjustment of the valve clearances, but it is essential that only good-quality oil of the recommended viscosity and specification is used in the engine, and that this oil is always changed at the recommended intervals. If this advice is not followed, the oilways and tappets may become clogged with particles of dirt, or deposits of burnt (inferior) engine oil, so that the system cannot work properly; ultimately, one or more of the tappets may fail, and expensive repairs may be required.

On starting the engine from cold, there will be a slight delay while full oil pressure builds up in all parts of the engine, especially in the tappets; the valve components, therefore, may well rattle for about 10 seconds or so, and then quieten. This is a normal state of affairs, and is nothing to worry about, provided that all tappets quieten quickly and stay quiet.

After the vehicle has been standing for several days, the valve components may rattle for longer than usual, as nearly all the oil will have drained away from the engines top end components and bearing surfaces.

While this is only to be expected, care must be taken not to damage the engine under these circumstances - avoid high speed running until all the tappets are refilled with oil and operating normally. With the vehicle stationary, hold the engine at no more than a fast idle speed (maximum 2000 to 2500 rpm) for 10 to 15 seconds, or until the noise ceases. Do not run the engine at more than 3000 rpm until the tappets are fully recharged with oil and the noise has ceased.

If the valve components are thought to be noisy, or if a light rattle persists from the top end after the engine has warmed up to normal operating temperature, take the vehicle to a Ford dealer for expert advice.

Depending on the mileage covered and the usage to which each vehicle has been put, some vehicles may be noisier than others; only a good mechanic experienced in these engines can tell if the noise level is typical for the vehicles mileage, or if a genuine fault exists. If any tappets operation is faulty, it must be renewed (Section 13).

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