ad blue FORD FIESTA 1989 Service Repair Manual

and evenly the pressure of the valve springs
on the caps.
5Withdraw the caps, noting their markings
and the presence of the locating dowels, then
remove the camshafts and withdraw their oil
seals. The inlet camshaft can be identified by
the reference lobe for the camshaft position
sensor; therefore, there is no need to mark the
camshafts (see illustrations) .
6 Obtain sixteen small, clean containers, and
number them 1 to 16. Using a rubber sucker,
withdraw each hydraulic tappet in turn, invert
it to prevent oil loss, and place it in its
respective container, which should then be
filled with clean engine oil (see illustrations).
Do not interchange the hydraulic tappets, or
the rate of wear will be much increased. Do
not allow them to lose oil, or they will take a
long time to refill on restarting the engine,
resulting in incorrect valve clearances.
Inspection
7 With the camshafts and hydraulic tappets
removed, check each for signs of obvious
wear (scoring, pitting etc) and for ovality, and
renew if necessary.
8 Measure the outside diameter of each
tappet (see illustration) - take measurements
at the top and bottom of each tappet, then a
second set at right-angles to the first; if any
measurement is significantly different from the
others, the tappet is tapered or oval and must be renewed. If the necessary equipment is
available, measure the inside diameter of the
corresponding cylinder head bore. Compare
the measurements obtained to those given
in the Specifications Section of this Chapter; if
the tappets or the cylinder head bores are
excessively worn, new tappets and/or a new
cylinder head will be required.
9
If the engine’s valve components have
sounded noisy, particularly if the noise
persists after initial start-up from cold, there is
reason to suspect a faulty hydraulic tappet.
Only a good mechanic experienced in these
engines can tell whether the noise level is
typical, or if renewal of one or more of the
tappets is warranted. If faulty tappets are
diagnosed, and the engine’s service history is
unknown, it is always worth trying the effect of
renewing the engine oil and filter (see Chap-
ter 1), using onlygood-quality engine oil of the
recommended viscosity and specification,
before going to the expense of renewing any
of the tappets - refer also to the advice in
Section 5 of this Chapter.
10 Visually examine the camshaft lobes for
score marks, pitting, galling (wear due to
rubbing) and evidence of overheating (blue,
discoloured areas). Look for flaking away of
the hardened surface layer of each lobe. If any
such signs are evident, renew the component
concerned. 11
Examine the camshaft bearing journals
and the cylinder head bearing surfaces for
signs of obvious wear or pitting. If any such
signs are evident, renew the component
concerned.
12 Using a micrometer, measure the
diameter of each journal at several points. If
the diameter of any one journal is less than
the specified value, renew the camshaft.
13 To check the bearing journal running
clearance, remove the hydraulic tappets, use
a suitable solvent and a clean lint-free rag to
clean carefully all bearing surfaces, then refit
the camshafts and bearing caps with a strand
of Plastigauge across each journal. Tighten
the bearing cap bolts to the specified torque
wrench setting (do not rotate the camshafts),
then remove the bearing caps and use the
scale provided to measure the width of the
compressed strands. Scrape off the
Plastigauge with your fingernail or the edge of
a credit card - don’t scratch or nick the
journals or bearing caps.
14 If the running clearance of any bearing is
found to be worn to beyond the specified
service limits, fit a new camshaft and
repeat the check; if the clearance is still
excessive, the cylinder head must be renewed.
15 To check camshaft endfloat, remove the
hydraulic tappets, clean the bearing surfaces
carefully, and refit the camshafts and bearing
Zetec engine in-car repair procedures 2C•9
11.6a Removing hydraulic tappets
11.5b Inlet camshaft has lobe for camshaft position sensor11.5a Note locating dowels when removing camshaft bearing caps
11.8 Use a micrometer to measurediameter of hydraulic tappets11.6b Hydraulic tappets must be stored as described in text
2C
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Pistons and piston rings
Piston diameter:1.0 and 1.1 litre engines:
Standard class 1 (or A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68.65 to 68.66 mm
Standard class 2 (or B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68.66 to 68.67 mm
Standard class 3 (or C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68.67 to 68.68 mm
Standard (service) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . 68.67 to 68.70 mm
Oversize 0.5 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 69.16 to 69.19 mm
Oversize 1.0 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 69.66 to 69.69 mm
1.3 litre engines:
Standard class 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 73.91 to 73.92 mm
Standard class 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 73.92 to 73.93 mm
Standard class 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 73.93 to 73.94 mm
Oversize 0.5 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 74.46 to 74.49 mm
Oversize 1.0 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 74.96 to 74.99 mm
Piston-to-cylinder bore clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.015 to 0.050 mm
Piston ring end gap - installed: Top compression ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. 0.25 to 0.45 mmSecond compression ring: 1.0 and 1.1 litre engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.25 to 0.45 mm
1.3 litre engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . 0.45 to 0.75 mm
Oil control ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 0.20 to 0.40 mm
Piston ring-to-groove clearance: Compression rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 0.20 mm (maximum)
Oil control ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 0.10 mm (maximum)
Ring gap position: Top compression ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. Offset 180º from oil control ring gap
Second compression ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Offset 90º from oil control ring gap
Oil control ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . Aligned with gudgeon pin
Gudgeon pin
Length: 1.0 and 1.1 litre engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58.6 to 59.4 mm
1.3 litre engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 63.3 to 64.6 mm
Diameter:
White colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . 18.026 to 18.029 mm
Red colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 18.029 to 18.032 mm
Blue colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 18.032 to 18.035 mm
Yellow colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 18.035 to 18.038 mm
Clearance in piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 0.008 to 0.014 mm
Interference fit in connecting rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.016 to 0.048 mm
Crankshaft and bearings
Main bearing journal diameter: 1.0 and 1.1 litre engines:
Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . 56.990 to 57.000 mm
Standard (with yellow line) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.980 to 56.990 mm
0.254 mm undersize (with green line) . . . . . . . . . . . . . . . . . . . . . . . 56.726 to 56.746 mm
0.508 mm undersize (service) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.472 to 56.492 mm
0.762 mm undersize (service) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.218 to 56.238 mm
1.3 litre engines: Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . 56.980 to 57.000 mm
0.254 mm undersize (with green line) . . . . . . . . . . . . . . . . . . . . . . . 56.726 to 56.746 mm
0.508 mm undersize (service) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.472 to 56.492 mm
0.762 mm undersize (service) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.218 to 56.238 mm
Main bearing journal-to-shell running clearance:
1.0 and 1.1 litre engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.009 to 0.046 mm
1.3 litre engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 0.009 to 0.056 mm
Crankpin (big-end) bearing journal diameter:
Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 40.99 to 41.01 mm
0.254 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . 40.74 to 40.76 mm
0.508 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . 40.49 to 40.51 mm
0.762 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . 40.24 to 40.26 mm
Crankpin (big-end) bearing journal-to-shell running clearance . . . . . . . 0.006 to 0.060 mm
Crankshaft endfloat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . 0.100 to 0.250 mm
Thrustwasher thickness: Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 2.80 to 2.85 mm
Oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 2.99 to 3.04 mm
2D•2 Engine removal and overhaul procedures
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Pistons and piston ringsPiston diameter (production):1.4 litre engine:
Standard 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 77.190 to 77.200 mm
Standard 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 77.200 to 77.210 mm
Standard 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 77.210 to 77.220 mm
Standard 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 77.220 to 77.230 mm
Oversize A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 77.480 to 77.490 mm
Oversize B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 77.490 to 77.500 mm
Oversize C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 77.500 to 77.510 mm
1.6 litre carburettor engine and turbocharged engine:
Standard 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.910 to 79.920 mm
Standard 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.920 to 79.930 mm
Standard 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.930 to 79.940 mm
Standard 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.940 to 79.950 mm
Oversize A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 80.200 to 80.210 mm
Oversize B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 80.210 to 80.220 mm
Oversize C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 80.220 to 80.230 mm
1.6 litre EFi (non-turbo) fuel injection engine: Standard 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.915 to 79.925 mm
Standard 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.925 to 79.935 mm
Standard 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.935 to 79.945 mm
Standard 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 79.945 to 79.955 mm
Oversize A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 80.205 to 80.215 mm
Oversize B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 80.215 to 80.225 mm
Oversize C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 80.225 to 80.235 mm
Piston-to-cylinder bore clearance: 1.4 litre engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 0.020 to 0.040 mm
1.6 litre carburettor engine and turbocharged engine . . . . . . . . . . . . 0.020 to 0.040 mm
1.6 litre EFi (non-turbo) fuel injection engine . . . . . . . . . . . . . . . . . . . 0.015 to 0.035 mm
Piston ring end gaps - installed:
Compression rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 0.30 to 0.50 mm
Oil control rings:1.4 litre engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 0.40 to 1.40 mm
1.6 litre carburettor engine and turbocharged engine . . . . . . . . . . 0.40 to 1.40 mm
1.6 litre EFi (non-turbo) fuel injection engine . . . . . . . . . . . . . . . . . 0.25 to 0.40 mm
Gudgeon pins
Length:1.4 litre engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 63.000 to 63.800 mm
1.6 litre carburettor engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66.200 to 67.000 mm
1.6 litre EFi (non-turbo) fuel injection engine . . . . . . . . . . . . . . . . . . . 63.000 to 63.800 mm
1.6 litre turbocharged engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.600 to 64.400 mm
Diameter: White colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . 20.622 to 20.625 mm
Red colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 20.625 to 20.628 mm
Blue colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 20.628 to 20.631 mm
Yellow colour code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 20.631 to 20.634 mm
Clearance in piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 0.005 to 0.011 mm
Interference fit in connecting rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.013 to 0.045 mm
Crankshaft and bearings
Main bearing journal diameter:
Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 57.98 to 58.00 mm
0.25 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 57.73 to 57.75 mm
0.50 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 57.48 to 57.50 mm
0.75 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 57.23 to 57.25 mm
Main bearing journal-to-shell running clearance . . . . . . . . . . . . . . . . . . 0.011 to 0.058 mm
Crankpin (big-end) bearing journal diameter: Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 47.89 to 47.91 mm
0.25 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 47.64 to 47.66 mm
0.50 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 47.39 to 47.41 mm
0.75 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 47.14 to 47.16 mm
1.00 mm undersize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 46.89 to 46.91 mm
Crankpin (big-end) bearing journal-to-shell running clearance . . . . . . . 0.006 to 0.060 mm
Crankshaft endfloat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . 0.09 to 0.30 mm
Thrustwasher thickness: Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 2.301 to 2.351 mm
Oversize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 2.491 to 2.541 mm
2D•4 Engine removal and overhaul procedures
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Torque wrench settingsNmlbf ft
Main bearing caps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 9570
Crankpin (big-end) bearing caps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3324
Engine-to-transmission bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4130
Note: Refer to Part B of this Chapter for remaining torque wrench settings.
Zetec engines
Cylinder head
Maximum permissible gasket surface distortion . . . . . . . . . . . . . . . . . . 0.10 mm
Valve seat included angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
90º
Valve guide bore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . 6.060 to 6.091 mm
Valves - generalInlet Exhaust
Valve length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 96.870 to 97.330 mm 96.470 to 96.930 mm
Valve head diameter: 1.6 litre engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 26.0 mm 24.5 mm
1.8 litre engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 32.0 mm 28.0 mm
Valve stem diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . 6.028 to 6.043 mm 6.010 to 6.025 mm
Valve stem-to-guide clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.017 to 0.064 mm 0.035 to 0.081 mm
Cylinder block
Cylinder bore diameter: 1.6 litre engine: Class 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 76.000 to 76.010 mm
Class 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 76.010 to 76.020 mm
Class 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 76.020 to 76.030 mm
1.8 litre engine:
Class 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 80.600 to 80.610 mm
Class 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 80.610 to 80.620 mm
Class 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 80.620 to 80.630 mm
Pistons and piston rings
Piston diameter1.6 litre engine: Class 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 75.975 to 75.985 mm
Class 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 75.985 to 75.995 mm
Class 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 75.995 to 76.005 mm
1.8 litre engine:
Class 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 80.570 to 80.580 mm
Class 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 80.580 to 80.590 mm
Class 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 80.590 to 80.600 mm
Oversizes - all engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
None available
Piston-to-cylinder bore clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Not specified
Piston ring end gaps - installed: Compression rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . 0.30 to 0.50 mm
Oil control ring: 1.6 litre engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 0.25 to 1.00 mm
1.8 litre engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 0.38 to 1.14 mm
Gudgeon pin
Diameter:
White colour code/piston crown marked “A” . . . . . . . . . . . . . . . . . . . 20.622 to 20.625 mm
Red colour code/piston crown marked “B” . . . . . . . . . . . . . . . . . . . . 20.625 to 20.628 mm
Blue colour code/piston crown marked “C” . . . . . . . . . . . . . . . . . . . . 20.628 to 20.631 mm
Clearance in piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . 0.010 to 0.016 mm
Interference fit in connecting rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.011 to 0.042 mm
Crankshaft and bearings
Main bearing journal standard diameter . . . . . . . . . . . . . . . . . . . . . . . . . 57.980 to 58.000 mm Main bearing journal-to-shell running clearance . . . . . . . . . . . . . . . . . . 0.011 to 0.058 mm
Main bearing shell undersizes available . . . . . . . . . . . . . . . . . . . . . . . . . 0.02 mm, 0.25 mmCrankpin (big-end) bearing journal standard diameter . . . . . . . . . . . . . . 46.890 to 46.910 mm
Crankpin (big-end) bearing journal-to-shell running clearance . . . . . . . 0.016 to 0.070 mm
Big-end bearing shell undersizes available . . . . . . . . . . . . . . . . . . . . . . 0.02 mm, 0.25 mm
Crankshaft endfloat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . 0.090 to 0.310 mm
Engine removal and overhaul procedures 2D•5
2D
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diameter from the bore measurement. If the
precision measuring tools shown are not
available, the condition of the pistons and
bores can be assessed, though not quite as
accurately, by using feeler gauges as follows.
Select a feeler gauge of thickness equal to the
specified piston-to-bore clearance, and slip it
into the cylinder along with the matching
piston. The piston must be positioned exactly
as it normally would be. The feeler gauge
must be between the piston and cylinder on
one of the thrust faces (at right-angles to the
gudgeon pin bore). The piston should slip
through the cylinder (with the feeler gauge in
place) with moderate pressure; if it falls
through or slides through easily, the clearance
is excessive, and a new piston will be
required. If the piston binds at the lower end
of the cylinder, and is loose toward the top,
the cylinder is tapered. If tight spots are
encountered as the piston/feeler gauge is
rotated in the cylinder, the cylinder is
out-of-round (oval).15 Repeat these procedures for the
remaining pistons and cylinder bores.
16 Compare the results with the
Specifications at the beginning of this
Chapter; if any measurement is beyond the
dimensions specified for that class (check the
piston crown marking to establish the class
of piston fitted), or if any bore measurement is
significantly different from the others
(indicating that the bore is tapered or oval),
the piston or bore is excessively-worn.
17 Worn pistons must be renewed; on some
engines, the pistons are available as Ford
replacement parts only as part of the
complete piston/connecting rod assembly.
See a Ford dealer or engine reconditioning
specialist for advice.
18 If any of the cylinder bores are badly
scuffed or scored, or if they are excessively-
worn, out-of-round or tapered, the usual
course of action would be to have the cylinder
block/crankcase rebored, and to fit new,
oversized, pistons on reassembly. See a Ford
dealer or engine reconditioning specialist for
advice.
19 If the bores are in reasonably good
condition and not excessively-worn, then it
may only be necessary to renew the piston
rings.
20 If this is the case, the bores should be
honed, to allow the new rings to bed in
correctly and provide the best possible seal.
Honing is an operation that will be carried out
for you by an engine reconditioning specialist.
21 After all the machining operations have
been carried out, the entire block/crankcase
must be washed very thoroughly with warm
soapy water to remove all traces of abrasive
grit produced during the machining
operations. When completely clean, rinse it
thoroughly and dry it, then lightly oil all
exposed machined surfaces to prevent
rusting.
22 The cylinder block/crankcase should now
be completely clean and dry, with all components checked for wear or damage,
and repaired or overhauled as necessary.
Refit as many ancillary components as
possible, for safekeeping. If reassembly is not
to start immediately, cover the block with a
large plastic bag to keep it clean.
14 Main and big-end bearings
-
inspection
4
1 Even though the main and big-end bearing
shells should be renewed during the engine
overhaul, the old shells should be retained for
close examination, as they may reveal
valuable information about the condition of
the engine (see illustration) .
2 Bearing failure occurs because of lack of
lubrication, the presence of dirt or other
foreign particles, overloading the engine, and
corrosion. Regardless of the cause of bearing
failure, it must be corrected before the engine
is reassembled, to prevent it from happening
again.
3 When examining the bearing shells, remove
them from the cylinder block/crankcase and
main bearing caps, and from the connecting
rods and the big-end bearing caps, then lay
them out on a clean surface in the same
general position as their location in the
engine. This will enable you to match any
bearing problems with the corresponding
crankshaft journal. Do nottouch any shell’s
bearing surface with your fingers while
checking it, or the delicate surface may be
scratched.
4 Dirt or other foreign matter gets into the
engine in a variety of ways. It may be left in
the engine during assembly, or it may pass
through filters or the crankcase ventilation
system. It may get into the oil, and from there
into the bearings. Metal chips from machining
operations and normal engine wear are often
present. Abrasives are sometimes left in
engine components after reconditioning,
especially when parts are not thoroughly
cleaned using the proper cleaning methods.
Whatever the source, these foreign objects
often end up embedded in the soft bearing
material, and are easily recognised. Large
particles will not embed in the material, and
will score or gouge the shell and journal. The
best prevention for this cause of bearing
failure is to clean all parts thoroughly, and to
keep everything spotlessly-clean during
engine assembly. Frequent and regular engine
oil and filter changes are also recommended.
5 Lack of lubrication (or lubrication
breakdown) has a number of inter-related
causes. Excessive heat (which thins the oil),
overloading (which squeezes the oil from
the bearing face) and oil leakage (from
excessive bearing clearances, worn oil pump
or high engine speeds) all contribute to
lubrication breakdown. Blocked oil passages,
which usually are the result of misaligned oil
holes in a bearing shell, will also starve a bearing of oil, and destroy it. When lack of
lubrication is the cause of bearing failure, the
bearing material is wiped or extruded from the
shell’s steel backing. Temperatures may
increase to the point where the steel backing
turns blue from overheating.
6
Driving habits can have a definite effect on
bearing life. Full-throttle, low-speed operation
(labouring the engine) puts very high loads on
bearings, which tends to squeeze out the oil
film. These loads cause the shells to flex,
which produces fine cracks in the bearing
face (fatigue failure). Eventually, the bearing
material will loosen in pieces, and tear away
from the steel backing.
7 Short-distance driving leads to corrosion of
bearings, because insufficient engine heat is
produced to drive off condensed water and
corrosive gases. These products collect in the
engine oil, forming acid and sludge. As the oil
is carried to the engine bearings, the acid
attacks and corrodes the bearing material.
8 Incorrect shell refitting during engine
assembly will lead to bearing failure as well.
Tight-fitting shells leave insufficient bearing
running clearance, and will result in oil
starvation. Dirt or foreign particles trapped
behind a bearing shell result in high spots on
the bearing, which lead to failure.
9 Do not touch any shell’s bearing surface
with your fingers during reassembly; there is a
risk of scratching the delicate surface, or of
depositing particles of dirt on it.
15 Engine overhaul -
reassembly sequence
1 Before reassembly begins ensure that all
new parts have been obtained and that all
necessary tools are available. Read through
the entire procedure to familiarise yourself with
the work involved, and to ensure that all items
Engine removal and overhaul procedures 2D•21
14.1 Typical bearing failures
2D
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7 Fuel pump/fuel pressure-
checking
3
Note: Refer to the warning note in Section 1
before proceeding.
Fuel pump operation check
1 Switch on the ignition, and listen for the fuel
pump (the sound of an electric motor running,
audible from beneath the rear seats).
Assuming there is sufficient fuel in the tank,
the pump should start and run for
approximately one or two seconds, then stop,
each time the ignition is switched on. Note:If
the pump runs continuously all the time the
ignition is switched on, the electronic control
system is running in the backup (or “limp-
home”) mode referred to by Ford as “Limited
Operation Strategy” (LOS). This almost
certainly indicates a fault in the EEC IV module
itself, and the vehicle should therefore be
taken to a Ford dealer for a full test of the
complete system, using the correct diagnostic
equipment; do not waste time or risk
damaging the components by trying to test
the system without such facilities.
2 Listen for fuel return noises from the fuel
pressure regulator. It should be possible to
feel the fuel pulsing in the regulator and in the
feed hose from the fuel filter.
3 If the pump does not run at all, check the
fuse, relay and wiring (see Chapter 12). Check
also that the fuel cut-off switch has not been
activated and if so, reset it.
Fuel pressure check
4 A fuel pressure gauge will be required for
this check and should be connected in the
fuel line between the fuel filter and the fuel rail,
in accordance with the gauge maker’s
instructions. On Zetec engines, a pressure
gauge equipped with an adapter to suit the
Schrader-type valve on the fuel rail pressure
test/release fitting (identifiable by its blue
plastic cap, and located on the union of the
fuel feed line and the fuel rail) will be required.
If the Ford special tool 29-033 is available, the
tool can be attached to the valve, and a
conventional-type pressure gauge attached to
the tool.
5 If using the service tool, ensure that its tap
is turned fully anti-clockwise, then attach it to
the valve. Connect the pressure gauge to the
service tool. If using a fuel pressure gauge
with its own adapter, connect it in accordance
with its maker’s instructions.
6 Start the engine and allow it to idle. Note
the gauge reading as soon as the pressure
stabilises, and compare it with the regulated
fuel pressure figures listed in the
Specifications .
a) If the pressure is high, check for a
restricted fuel return line. If the line is
clear, renew the fuel pressure regulator.
b) If the pressure is low, pinch the fuel return
line. If the pressure now goes up, renew the fuel pressure regulator. If the pressure
does not increase, check the fuel feed
line, the fuel pump and the fuel filter.
7 Detach the vacuum hose from the fuel
pressure regulator; the pressure shown on the
gauge should increase. Note the increase in
pressure, and compare it with that listed in the
Specifications . If the pressure increase is not
as specified, check the vacuum hose and
pressure regulator.
8 Reconnect the regulator vacuum hose, and
switch off the engine. Verify that the hold
pressure stays at the specified level for five
minutes after the engine is turned off.
9 Carefully disconnect the fuel pressure
gauge, depressurising the system first as
described in Section 2. Be sure to cover the
fitting with a rag before slackening it. Mop up
any spilt petrol.
10 Run the engine, and check that there are
no fuel leaks.
8 Fuel tank - removal,
inspection and refitting
3
Proceed as described in Part A, Section 8,
but before disconnecting the battery, relieve
the residual pressure in the fuel system (see
Section 2), and equalise tank pressure by
removing the fuel filler cap.
9 Fuel pump/fuel gauge sender unit - removal and
refitting
3
Refer to Part B, Section 9.
10 Fuel tank ventilation tube -
removal and refitting
3
Refer to Part A, Section 10, but note that
the ventilation tube connects to the combined
roll-over/anti-trickle-fill valve assembly but,
instead of venting to atmosphere, a further
tube runs the length of the vehicle to the
evaporative emission control system carbon canister in the front right-hand corner of the
engine compartment.
Further information on the evaporative
emission control system is contained in Part E
of this Chapter.
11 Fuel tank filler pipe -
removal and refitting
3
Refer to Part A, Section 11.
12 Fuel cut-off switch -
removal and refitting
1
Refer to Part B, Section 12.
13 Fuel injection system -
checking
3
Refer to Part B, Section 13
14 Fuel injection system components - removal and
refitting
3
Note: Refer to the warning note in Section 1
before proceeding.
Throttle housing
1 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
2 Remove the air inlet components as
described in Section 4.
3 Disconnect the accelerator cable from the
throttle linkage (see Section 5).
4 Disconnect the throttle position sensor
multi-plug.
5 Unscrew the retaining bolts, and detach the
accelerator cable support bracket at the
throttle housing (see illustration) .
6 Unscrew the throttle housing-to-manifold
retaining bolts (see illustration) , and unbolt
the throttle housing support bracket bolts
(where fitted). Remove the throttle housing
4D•4 Fuel system - sequential electronic fuel injection engines
14.6 Throttle housing retaining bolts
(arrowed)14.5 Unscrew the retaining bolts (arrowed),and detach the accelerator cable support
bracket
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d)Refit the remaining parts in the reverse
order of removal. Tighten all fasteners to
the specified torque wrench settings
where given.
e) Where drained, refill the cooling system (see Chapter 1).
f) Run the engine, and check for exhaust
leaks. Check the coolant level when fully
warmed-up to normal operating
temperature.
4 Catalytic converter - general
information and precautions
The catalytic converter is a reliable and
simple device, which needs no maintenance
in itself, but there are some facts of which an
owner should be aware if the converter is to
function properly for its full service life. a) DO NOT use leaded petrol in a vehicle equipped with a catalytic converter - the
lead will coat the precious metals,
reducing their converting efficiency, and
will eventually destroy the converter.
b) Always keep the ignition and fuel systems
well-maintained in accordance with the
manufacturer’s schedule (see Chapter 1).
c) If the engine develops a misfire, do not drive the vehicle at all (or at least as little
as possible) until the fault is cured.
d) DO NOT push - or tow-start the vehicle -
this will soak the catalytic converter in
unburned fuel, causing it to overheat
when the engine does start.
e) DO NOT switch off the ignition at high engine speeds, ie do not “blip” the
throttle immediately before switching off.
f) DO NOT use fuel or engine oil additives - these may contain substances harmful to
the catalytic converter.
g) DO NOT continue to use the vehicle if the
engine burns oil to the extent of leaving a
visible trail of blue smoke.
h) Remember that the catalytic converter
operates at very high temperatures. DO
NOT, therefore, park the vehicle in dry
undergrowth, over long grass or piles of
dead leaves, after a long run.
I) Remember that the catalytic converter is FRAGILE. Do not strike it with tools
during servicing work.
j) In some cases, a sulphurous smell (like
that of rotten eggs) may be noticed from
the exhaust. This is common to many
catalytic converter-equipped vehicles.
Once the vehicle has covered a few
thousand miles, the problem should
disappear. Low quality fuel with a high
sulphur content will exacerbate this effect.
k) The catalytic converter used on a well-
maintained and well-driven vehicle should
last for between 50 000 and
100 000 miles. If the converter is no
longer effective, it must be renewed.
5 Positive crankcase ventilation system - checking
and component renewal
2
Checking
1 Checking procedures for the system
components are included in Chapter 1.
Component renewal - all
engines except Zetec
Air cleaner components
2 See Chapter 1.
Filter/oil separator and hoses
3All the components relating to the positive
crankcase ventilation system, with the
exception of the HCS engine filter/adapter
located on the underside of the air cleaner,
may be removed by simple disconnection and
withdrawal (having noted all connections for
subsequent refitting).
4 The refitting of all components is a reversal
of the removal procedure, ensuring that the
connections are correctly made.
Component renewal - Zetec
engines
Air cleaner components
5 See Chapter 1.
Positive Crankcase Ventilation (PCV)
valve
6The valve is plugged into the oil separator
on Zetec engines (see illustration).Depending on the tools available, access to
the valve may be possible once the pulse-air
assembly has been removed (see Section 7).
If this is not feasible, proceed as outlined in
paragraph 7 below.
Oil separator
7
Remove the exhaust manifold (see Sec-
tion 3). The positive crankcase ventilation
valve can now be unplugged and flushed, or
renewed, as required, as described in Chap-
ter 1.
8 Unbolt the oil separator from the cylinder
block/crankcase, and withdraw it; remove and
discard the gasket.
9 Flush out or renew the oil separator, as
required (see Chapter 1).
10 Refitting is the reverse of the removal
procedure, but use a new gasket between the
oil separator and cylinder block. Refill the
cooling system (see Chapter 1). Run the
engine, check for exhaust leaks, and check
the coolant level when it is fully warmed-up.
6 Evaporative emissions control system - checking
and component renewal
2
Checking
1 Poor idle, stalling and poor driveability can
be caused by an inoperative canister-purge
solenoid valve, a damaged canister, split or
cracked hoses, or hoses connected to the
wrong fittings. Check the fuel filler cap for a
damaged or deformed gasket.
Exhaust and emission control systems 4E•5
5.6 Crankcase emission control system (Zetec engine models)
1 Oil separator
2 Gasket
3 Positive crankcase ventilation (PCV) valve 4 Cylinder block/crankcase opening
5 Crankcase breather pipe and flexible
hoses
4E
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flux can pass between the magnet and the
sensor. When a trigger vane segment is in line
with the sensor, the magnetic flux is diverted
through the trigger vane, away from the
sensor. The sensor detects the change in
magnetic flux and sends an impulse to the
EEC IV module. Additional data is received
from the engine coolant temperature sensor,
manifold absolute pressure sensor, inlet air
temperature sensor, throttle position sensor
and vehicle speed sensor. Using this
information the EEC IV module calculates the
optimum ignition advance setting and
switches off the low tension circuit via the
ignition module. This results in the collapse of
the magnetic field in the coil which generates
the high tension voltage. The high tension
voltage is then fed, via the coil HT lead and
the carbon brush in the centre of the
distributor cap, to the rotor arm. The voltage
passes across to the appropriate metal
segment in the cap and via the spark plug HT
lead to the spark plug where it finally jumps
the spark plug gap to earth. It can be seen
that the ignition module functions basically as
a high current switch by controlling the low
tension supply to the ignition coil primary
windings.In the event of failure of a sensor, the
EEC IV module will substitute a preset value
for that input to allow the system to continue
to function. In the event of failure of the
EEC IV module, a “limited operation strategy”
(LOS) function allows the vehicle to be driven,
albeit at reduced power and efficiency. The
EEC IV module also has a “keep alive
memory” (KAM) function which stores idle and
drive values and codes which can be used to
indicate any system fault which may occur.
Distributorless ignition systems
The main ignition system components
include the ignition switch, the battery, the
crankshaft speed/position sensor, the ignition
module, the coil, the primary (low tension/LT)
and secondary (high tension/HT) wiring
circuits, and the spark plugs. The system used on carburettor models is
termed DIS (Distributorless Ignition System),
and on fuel injection models E-DIS, (Electronic
Distributorless Ignition System). The primary
difference between the two is that the DIS
system is an independent ignition control
system while the E-DIS system operates in
conjunction with the EEC IV engine
management module which also controls the
fuel injection and emission control systems.
With both systems, the main functions of
the distributor are replaced by a computerised
ignition module and a coil unit. The coil unit
combines a double-ended pair of coils - each
time a coil receives an ignition signal, two
sparks are produced, at each end of the
secondary windings. One spark goes to a
cylinder on compression stroke and the other
goes to the corresponding cylinder on its
exhaust stroke. The first will give the correct power stroke, but the second spark will have
no effect (a “wasted spark”), occurring as it
does during exhaust conditions.
The ignition signal is generated by a
crankshaft position sensor which scans a
series of 36 protrusions on the periphery of
the engine flywheel. The inductive head of the
crankshaft position sensor runs just above the
flywheel periphery and as the crankshaft
rotates, the sensor transmits a pulse to the
ignition module every time a protrusion
passes it. There is one missing protrusion in
the flywheel periphery at a point
corresponding to 90° BTDC. The ignition
module recognises the absence of a pulse
from the crankshaft position sensor at this
point to establish a reference mark for
crankshaft position. Similarly, the time interval
between absent pulses is used to determine
engine speed. On carburettor engines, the ignition module
receives signals provided by information
sensors which monitor various engine
functions (such as crankshaft position,
coolant temperature, inlet air temperature,
inlet manifold vacuum etc). This information
allows the ignition module to generate the
optimum ignition timing setting under all
operating conditions.
On fuel injection engines, the ignition
module operates in conjunction with the
EEC IV engine management module, and
together with the various additional
information sensors and emission control
components, provides total control of the fuel
and ignition systems to form a complete
engine management package. The information contained in this Chapter
concentrates on the ignition-related
components of the engine management
system. Information covering the fuel, exhaust
and emission control components can be
found in the applicable Parts of Chapter 4.
Precautions
When working on the ignition system, take
the following precautions:
a) Do not keep the ignition switch on for
more than 10 seconds if the engine will
not start.
b) If a separate tachometer is ever required
for servicing work, consult a dealer
service department before buying a
tachometer for use with this vehicle -
some tachometers may be incompatible
with these types of ignition systems - and
always connect it in accordance with the
equipment manufacturer’s instructions.
c) Never connect the ignition coil terminals to earth. This could result in damage to
the coil and/or the ignition module.
d) Do not disconnect the battery when the
engine is running.
e) Make sure that the ignition module is
properly earthed.
f) Refer to the warning at the beginning of the next Section concerning HT voltage.
2 Ignition system - testing
2
Warning: Voltages produced by
an electronic ignition system are
considerably higher than those
produced by conventional
ignition systems. Extreme care must be
taken when working on the system with
the ignition switched on. Persons with
surgically-implanted cardiac pacemaker
devices should keep well clear of the
ignition circuits, components and test
equipment.
Note: Refer to the precautions given in
Section 1 of Part A of this Chapter before
starting work. Always switch off the ignition
before disconnecting or connecting any
component and when using a multi-meter to
check resistances.
1 If the engine turns over but won’t start,
disconnect the (HT) lead from any spark plug,
and attach it to a calibrated tester (available at
most automotive accessory shops). Connect
the clip on the tester to a good earth - a bolt
or metal bracket on the engine. If you’re
unable to obtain a calibrated ignition tester,
have the check carried out by a Ford dealer
service department or similar. Any other form
of testing (such as jumping a spark from the
end of an HT lead to earth) is not
recommended, because of the risk of
personal injury, or of damage to the ignition
module.
2 Crank the engine, and watch the end of the
tester to see if bright blue, well-defined sparks
occur.
3 If sparks occur, sufficient voltage is
reaching the plug to fire it. Repeat the
check at the remaining plugs, to ensure
that all leads are sound and that the
coil is serviceable. However, the plugs
themselves may be fouled or faulty, so
remove and check them as described in
Chapter 1.
4 If no sparks or intermittent sparks occur,
the spark plug lead(s) may be defective. Also,
on distributor systems, there may be
problems with the rotor arm or distributor cap
- check all these components as described in
Chapter 1.
5 If there’s still no spark, check the coil’s
electrical connector (where applicable), to
make sure it’s clean and tight. Check for full
battery voltage to the coil at the connector’s
centre terminal. Check the coil itself (see
Section 3). Make any necessary repairs, then
repeat the check again.
6 The remainder of the system checks should
be left to a dealer service department
or other qualified repair facility, as there is a
chance that the ignition module may
be damaged if tests are not performed
properly.
Ignition system 5B•3
5B
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1595 Ford Fiesta Remake
MOT test checksREF•13
REF
MExamine the handbrake mechanism,
checking for frayed or broken cables,
excessive corrosion, or wear or insecurity of
the linkage. Check that the mechanism works
on each relevant wheel, and releases fully,
without binding.
M It is not possible to test brake efficiency
without special equipment, but a road test can
be carried out later to check that the vehicle
pulls up in a straight line.
Fuel and exhaust systems
M Inspect the fuel tank (including the filler
cap), fuel pipes, hoses and unions. All
components must be secure and free fr om
leaks.
M Examine the exhaust system over its entire
length, checking for any damaged, broken or
missing mountings, security of the retaining
clamps and rust or corrosion.
Wheels and tyres
M Examine the sidewalls and tread area of
each tyre in turn. Check for cuts, tears, lumps,
bulges, separation of the tread, and exposure
of the ply or cord due to wear or damage.
Check that the tyre bead is correctly seated
on the wheel rim, that the valve is sound and pr
operly seated, and that the wheel is not
distorted or damaged.
M Check that the tyres are of the correct size
for the vehicle, that they are of the same size
and type on each axle, and that the pressur es
ar e correct.
M Check the tyre tread depth. The legal
minimum at the time of writing is 1.6 mm over
at least three-quarters of the tread width.
Abnormal tread wear may indicate incorrect
fr ont wheel alignment.
Body corrosion
M Check the condition of the entire vehicle
structur e for signs of corrosion in load-bearing
ar eas. (These include chassis box sections,
side sills, cross-members, pillars, and all
suspension, steering, braking system and
seat belt mountings and anchorages.) Any
corrosion which has seriously reduced the
thickness of a load-bearing area is likely to
cause the vehicle to fail. In this case
pr ofessional repairs are likely to be needed.
M Damage or corrosion which causes sharp
or otherwise dangerous edges to be exposed
will also cause the vehicle to fail.
Petrol models
M Have the engine at normal operating
temperatur e, and make sure that it is in good
tune (ignition system in good order, air filter
element clean, etc).
M Befor e any measurements are carried out,
raise the engine speed to around 2500 rpm,
and hold it at this speed for 20 seconds. Allow the engine speed to return to idle, and watch
for smoke emissions from the exhaust
tailpipe. If the idle speed is obviously much
too high, or if dense blue or clearly-visible
black smoke comes from the tailpipe for more
than 5 seconds, the vehicle will fail. As a rule
of thumb, blue smoke signifies oil being burnt
(engine wear) while black smoke signifies
unbur nt fuel (dirty air cleaner element, or other
carbur ettor or fuel system fault).
M An exhaust gas analyser capable of
measuring carbon monoxide (CO) and
hydr ocarbons (HC) is now needed. If such an
instrument cannot be hired or borrowed, a
local garage may agree to perform the check
for a small fee.
CO emissions (mixture)
M At the time of writing, the maximum CO
level at idle is 3.5% for vehicles first used after
August 1986 and 4.5% for older vehicles.
Fr om January 1996 a much tighter limit
(ar ound 0.5%) applies to catalyst-equipped
vehicles first used from August 1992. If the
CO level cannot be reduced far enough to
pass the test (and the fuel and ignition
systems are otherwise in good condition) then
the carburettor is badly worn, or there is some
pr oblem in the fuel injection system or
catalytic converter (as applicable).
HC emissionsM With the CO emissions within limits, HC
emissions must be no more than 1200 ppm
(parts per million). If the vehicle fails this test
at idle, it can be re-tested at around 2000 rpm;
if the HC level is then 1200 ppm or less, this
counts as a pass.
M Excessive HC emissions can be caused by
oil being burnt, but they are more likely to be
due to unburnt fuel.
Diesel models
M The only emission test applicable to Diesel
engines is the measuring of exhaust smoke
density . The test involves accelerating the
engine several times to its maximum
unloaded speed.
Note: It is of the utmost importance that the
engine timing belt is in good condition before
the test is carried out.
M
Excessive smoke can be caused by a dirty
air cleaner element. Otherwise, professional
advice may be needed to find the cause.
4Checks carried out on
YOUR VEHICLE’S EXHAUST
EMISSION SYSTEM
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