1993 FORD MONDEO gas mileage

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
head’s 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
engine’s 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 system’s 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
onlygood-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 engine’s
top end components and bearing surfaces.
While this is only to be expected, care mustbe 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 vehicle’s mileage, or if a genuine fault
exists. If any tappet’s operation is faulty, it
must be renewed (Section 13).
The following major repair operations can
be accomplished without removing the
engine from the vehicle. However, owners
should note that any operation involving the
removal of the sump requires careful
forethought, depending on the level of skill
and the tools and facilities available; refer to
the relevant text for details.
(a) Compression pressure - testing.
(b) Cylinder head cover - removal and
refitting.
(c) Timing belt covers - removal and refitting.
(d) Timing belt - renewal.
(e) Timing belt tensioner and toothed pulleys
- removal and refitting.
(f) Camshaft oil seals - renewal.
(g) Camshafts and hydraulic tappets -
removal and refitting.
(h) Cylinder head - removal, overhaul and
refitting.
(i) Cylinder head and pistons -
decarbonising.
(j) Sump - removal and refitting.
(k) Crankshaft oil seals - renewal.
(l) Oil pump - removal and refitting.
(m) Piston/connecting rod assemblies -
removal and refitting (but see note below).
(n) Flywheel/driveplate - removal and
refitting.
(o) Engine/transmission mountings - removal
and refitting.
Clean the engine compartment and the
exterior of the engine with some type of
degreaser before any work is done. It will
make the job easier, and will help to keep dirt
out of the internal areas of the engine.
Depending on the components involved, it
may be helpful to remove the bonnet, to
improve access to the engine as repairs are
performed (refer to Chapter 11 if necessary).Cover the wings to prevent damage to the
paint; special covers are available, but an old
bedspread or blanket will also work.
If vacuum, exhaust, oil or coolant leaks
develop, indicating a need for component/
gasket or seal replacement, the repairs can
generally be made with the engine in the
vehicle. The intake and exhaust manifold
gaskets, sump gasket, crankshaft oil seals
and cylinder head gasket are all accessible
with the engine in place.
Exterior components such as the intake
and exhaust manifolds, the sump, the oil
pump, the water pump, the starter motor, the
alternator and the fuel system components
can be removed for repair with the engine in
place.
Since the cylinder head can be removed
without lifting out the engine, camshaft and
valve component servicing can also be
accomplished with the engine in the vehicle,
as can renewal of the timing belt and toothed
pulleys.
In extreme cases caused by a lack of
necessary equipment, repair or renewal of
piston rings, pistons, connecting rods and
big-end bearings is possible with the engine
in the vehicle. However, this practice is not
recommended, because of the cleaning and
preparation work that must be done to the
components involved, and because of the
amount of preliminary dismantling work
required - these operations are therefore
covered in Part B of this Chapter.
1When engine performance is down, or if
misfiring occurs which cannot be attributed to
the ignition or fuel systems, a compression
test can provide diagnostic clues as to the
engine’s condition. If the test is performed
regularly, it can give warning of trouble before
any other symptoms become apparent.
2The engine must be fully warmed-up to
normal operating temperature, the oil level
must be correct, the battery must be fully
charged, and the spark plugs must be
removed. The aid of an assistant will be
required also.
3Disable the ignition system by unplugging
the ignition coil’s electrical connector, and
remove fuse 14 to disconnect the fuel pump.
4Fit a compression tester to the No 1
cylinder spark plug hole - the type of tester
which screws into the plug thread is to be
preferred.
5Have the assistant hold the throttle wide
open and crank the engine on the starter
motor; after one or two revolutions, the
compression pressure should build up to a
maximum figure, and then stabilise. Record
the highest reading obtained.
6Repeat the test on the remaining cylinders,
recording the pressure developed in each.
7At the time of writing, no compression
3 Compression test -
description and interpretation
2 Repair operations possible with
the engine in the vehicle
In-car engine repair procedures 2A•5
2A
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