Engine Tune-up 27
move the alternator or power steering pump as
required until the drive belt concerned has the
specified deflection.
On models with air conditioning, loosen the nut
in the centre of the idler pulley and turn the adjusting
bolt until the drive belt has the specified deflection.
(3) Tighten the alternator or power steering
pump bolts securely and check the belt tension.
On models with air conditioning, tighten the idler
pulley nut securely.
TO SERVICE SPARK PLUGS
The spark plugs should be renewed at intervals of
40 000 km.
Before removing the spark plugs ensure that the
area around each plug is cl ean to prevent foreign
matter entering the cylinder when the plugs are
removed.
Spark plugs removed from an engine in good
mechanical condition should have a light powdery
deposit ranging from light brown to grayish tan in
color. After considerable service the electrodes will
show signs of wear or no rmal burning. Spark plugs
showing a thick black oily deposit indicate an engine
in poor mechanical condition or possibly, that a plug
with too low a heat range has been installed.
Spark plugs showing a white or yellowish deposit
indicate sustained high speed driving or possibly that
plugs with too high a heat range have been installed,
particularly when these deposits are accompanied by
blistering of the porcelain and burning of the elec-
trodes.
If the spark plugs are to be cleaned, use a
sandblasting machine and blow clean with com-
pressed air. Ensure that all traces of abrasive grit are
removed from the spark plug threads and from the
well in the plug body. Carefully open the electrode gap
a little, by bending the side electrode, and lightly file
the electrodes flat with a points file.
Black damp deposits can be caused by excessive oil
consumption or incorrect plug type. Spark plugs in this
condition are usually not firing.
Cutaway view of spark plug showing a crack in the
insulator nose which can be caused by exerting pres-
sure against the centre electrode when adjusting the
gap. The other crack shown on the insulator is caused
by tilting the plug spanner.
When plug electrodes are eroded to this degree the
spark can be considered worn out and should be
renewed using a plug of the recommended heat range
.
CRACK
Engine Tune-up
Spark plug with burnt electrodes and white blistered
appearance, possibly due to incorrect plug type, loose
plug or motor running too hot.
NOTE: Never attempt to alter the electrode
gap by bending the centre electrode as
damage to the porcelain insulator will
result.
Before installing any spark plugs measure the gap
between the electrodes, pref erably with clean wire
gauges. If wire gauges are una vailable, use clean feeler
gauges. Move the side electrode towards or away from
the centre electrode to obtain the correct gap-
Screw the plugs into the cylinder head ringer tight,
then use a torque wrench to tighten the plugs lo the
specified torque.
Checking the spark plug electrode gap with a wire
gauge.
NOTE: If a torque wrench is unavailable,
extreme care must be taken when tightening
the spark plugs as over tightening may lead
to stripping of the thread from the cylinder
head. If the plugs are tightened with the
fingers and then taken up an additional 1/4
of a turn with a spark plug wrench, they will
be tight enough.
TO TEST COMPRESSION
(1) With the engine at operating temperature.
disconnect the high tension leads from the spark
plugs.
(2) Ensure that the area around each spark plug
is clean to prevent foreign matter entering the cylin-
ders and remove the spark plugs. (3) Remove the fusible link that is positioned
third from the front of th e fusible link connecting
block, located at the rear of the battery. Disconnect
the coil high tension lead from the coil.
NOTE: Failure to remove the fusible link
can result in an explosion.
(4) Install a compression gauge to number one
spark hole according to the gauge manufacturers
instructions. (5) Have an assistant fully open the throttle and
operate the starter switch to rotate the engine. Ob-
serve the compression gauge and stop the engine when
the gauge has reached the highest reading, usually
after 3 or 4 compression strokes.
(6) Record the reading a nd check the compres-
sion of the remaining cylinders in the same manner.
(7) Compare all the readings taken. Variation
between the highest and lowest reading cylinders
should not exceed 100 kPa. (8) If a low reading is recorded on one or more
cylinders the trouble may be isolated as follows :
Lightly file the plug electrodes flat with a points file
Engine Tune-up 29
Check the cylinder compressions using a compression gauge.
(a) Inject a small amount of engine oil into the
spark plug hole of the cylinder concerned ensuring
that the oil is evenly distributed within the cylinder by
rotating the engine.
(b) Repeat the compression test on the cylinder
concerned.
A substantial increase of compression pressure
indicates faulty or worn piston rings, pistons or
cylinder.
No increase of compression pressure indicates
burnt, obstructed or sticking valves, or a leaking or
blown cylinder head gasket.
(9) Install the fusible li nk and connect the high
tension lead to the coil.
TO SERVICE THE DISTRIBUTOR
The electronic ignition system requires virtually
no maintenance except for checking of the distributor
cap. rotor and high tension leads as described below.
Refer to the Fuel and Engine Management section
for Specifications and Trouble Shooting.
NOTE: When working on or near electronic
ignition systems, care should be taken as
dangerous high voltages are present in both
the primary and secondary circuits.
The ignition switch should be turned off
before removing or inst alling any electrical
connections otherwise damage to the igni-
tion system as well as severe electrical shock
could result.
TO SERVICE HIGH TENSION LEADS
Check the leads for perishing or cracking and
renew as required. Never a ttempt to repair defective
carbon impregnated core leads.
The lead may be carefully cleaned, using cloth
moistened with kerosene a nd then wiped completely
dry.
If an ohmmeter is available the electrical resis-
tance of the leads may be checked as follows:
View showing the location of the fusible links.
Check the spark plug high tension leads for cracks and
burnt or corroded terminals.
Check the distributor cap for cracks or tracking
between the terminals
.
30 Engine Tune-up
(1) With the distributor cap and leads removed
as an assembly, test one lead at a time, connecting the
meter probes at the spark plug end of the lead and at
the corresponding terminal in side the cap. Resistance
should be less than 15 000 ohms.
(2) If the resistance is more than 15 000 ohms
remove the lead from the distributor cap and check
(he resistance in the lead only. The lead should be
renewed if the resistance is still more than 15 000
ohms. (3) High distributor cap resistance may be due
to corrosion deposits on the cap terminals. These
deposits should be removed with a small scraper or
emery cloth. Check the distributor cap for cracks or tracking
between the high tension terminals on both the inside
and outside of the cap. Renew the cap if cracks or
tracking are evident.
Check the carbon brush in the centre of the
distributor cap for evidence of arcing and renew as
necessary.
Check the condition of the rotor and renew if
arced excessively or cracked.
HOW TO CONNECT ELECTRICAL TEST
EQUIPMENT
NOTE: Some types of tachometers, timing
lights and ignition system analysers are not
compatible with this type of electronic igni-
tion system and may result in incorrect
readings. It is therefore recommended that
the manufacturer of the test equipment be
consulted before using the equipment.
Do not allow the tachometer lead connec-
tor to short to earth as damage to the test
equipment or ignition system may result.
Timing Light
(1) Connect the timing light to the engine fol-
lowing the instrument manufacturers instructions.
NOTE: Do not connect or disconnect the
timing light with the engine running as
voltage surges could damage the alternator.
Do not allow the high tension leads to open
circuit as damage to the ignition system
could result.
(2) Where necessary, connect the power leads of
the timing light to an external power source to prevent
possible transient voltages in the timing light damag-
ing the vehicle alternator.
Tachometer
(1) Ensure that the tachometer is compatible
with the vehicle ignition system. (2) Disconnect the resistor from the tachometer
View showing the location of the tachometer pickup
wiring connector with the resistor installed
.
pick up wiring connector which is located on the
ignition coil wiring harness, and connect the positive
lead of an accurate tachometer to the brown wire
terminal in the wiring connector.
(3) Connect the negative lead to a good earthing
point.
TO CHECK AND ADJUST IGNITION TIMING
( 1 ) Connect an accurate tachometer and timing
light to the engine as previously described.
View showing the location of the diagnostic link
connector. Passengers seat removed for clarity.
Inset shows the diagnostic link connector terminal
identification.
(2) Start the engine and allow it to reach normal
operating temperature. (3) Connect a jumper lead between terminals A
and B on the diagnostic link connector. (4) With the engine idling at the specified speed,
check the ignition timing with the timing light.
Correct timing exists when the marks on the
crankshaft pulley are aligned with the pointer on the
inner timing cover.
Roadside Trouble Shooting
ing the wiring from any component, ensure
that the ignition switch is off and the
negative battery terminal is disconnected to
prevent damage to the solid state circuitry.
(4) Open the electrode gap of a serviceable spark
plug to 6 mm. Securely earth the plug using a jumper
lead or by tying the plug to an earthed engine
component.
(5) Disconnect the high tension lead from a
spark plug and connect it to the test spark plug.
(6) Have an assistant operate the starter motor.
(7) Check that a spark, if any, jumps the gap on
the test spark plug. If the spark is satisfactory, proceed to operation
(8).
If there is no spark, proceed as follows:
(a) Check the high tension leads to ensure that
they are dry and that the insulation is not cracked or
perished. Check the ends of the leads for burning. Using an ohmmeter, measure the resistance in
each high tension lead. The resistance should be no
more than 15 000 ohms per lead.
(b) Check the distributor cap to ensure that it is
dry and clean. Examine both the inside and outside of
the cap for cracks or tracki ng, particularly between the
high tension lead segments.
Check that the carbon brush in the centre of the
distributor cap interior fa ce is clean and dry and
ensure that the brush moves freely in and out of its
locating hole.
(c) Check the rotor arm for cracks, deposits and
burning on the metal arm. (d) Ensure that the high tension leads have dry.
clean and secure connections on the distributor cap. (8) If the above checks r esult in a good spark at
the spark plug high tension leads but the engine is still
not operating satisfac torily, remove all the spark plugs
and check the condition and electrode gap as de-
scribed in the Engine Tune-up section under the
appropriate heading.
3. TO CHECK FUEL SYSTEM
Due to the complex nature of the EFI system, it is
recommended that should the following checks prove
satisfactory but the engine fail to start, reference be
made to the Fuel and Engine Management section of
this manual or a Nissan workshop be consulted.
(1) Check that the fuel tank contains a reason-
able amount of fuel. (2) Have an assistant switch the ignition on and
off while squeezing the fuel supply hose with the
fingers. If the fuel pump is operating it should be
possible to feel the fuel pr essure increase for approx-
imately two seconds.
NOTE: When conducting the above test it
should be possible to hear the fuel pump and
ignition relays clicking when the ignition is
switched on and off
If the fuel pump relay fails, power will be
supplied to the fuel pump via the oil pressure
Check the distributor cap for cracks or tracking between the terminals. Squeeze the fuel supply hose while the ignition is
switched On. An increase in pressure should be felt.
Check the spark plug high tension leads for cracks and
burnt or corroded terminals.
Roadside Trouble Shooting 35
View showing the location of the fuel pump fuse and the EGI and fuel pump relays.
switch. When starting the engine, the fuel
pump will not operate until the oil pressure
is sufficient to extinguish the oil pressure
warning lamp. Therefore it will be necessary
to operate the starter motor for a longer
period than usual to start the engine.
(3) If the fuel pump cannot be felt operating,
check the fuel pump fuse located in the fuse panel
adjacent to the steering column.
If the fuel pump fuse is serviceable, refer to the
Fuel and Engine Management section for detailed
tests on the fuel pump.
(4) Check that all fuel hose connections are
secure.
(5) Remove the spark plugs and check for petrol
saturation of the electrodes which indicates flooding.
Thoroughly clean and dry the spark plugs before
replacement. Fully depress the throttle pedal and turn the
ignition switch to the start position. If the engine does
not start, proceed as follows.
Check that the MAP sensor hose is not blocked or split
and ensure that all electrical connections are clean and
secure.
If flooding persists, refer to the Fuel and Engine
Management section.
(6) Check that all EFI electrical wiring connec-
tors are clean and secure.
(7) Check that the MAP sensor vacuum hose is
securely connected at each end and is not split or
blocked.
4. TO CHECK MECHANICAL SYSTEM
The following check procedure assumes that the
starter motor will rotate the engine. If not, on manual
transaxle models, depress the clutch pedal to disen-
gage the engine from the tr ansaxle in case the fault lies
within the transaxle.
If the starter motor will not rotate the engine, it
will be necessary to remove the starter motor and
attempt to turn the engine over manually. This will
establish whether the fault lies with the starter motor,
which could be jammed or defective, or with the
engine, which could be seized or have broken internal
components such as connecting rods, pistons and
crankshafts etc.
If the starter motor is not at fault and the engine
will not rotate manually, refer to the Engine Mechan-
ical Trouble Shooting heading in the Engine section.
It should be noted that the only way that cylinder
compression can be accurately tested is with a com-
pression gauge. The method described in the following
procedure is only intended to give a rough indication
when checking for causes of engine breakdown,
(I) When the engine is cool, check for loss of
coolant from the cooling system.
If coolant loss is evident, check carefully for any
indication of external leakage. Remove the engine oil
dipstick and check for wate r contamination (emulsi-
fication) of the oil. When oil mixes with water it will
Ensure that all fuel connections are securely tightened.
36 Roadside Trouble Shooting
Check the engine oil for level and dilution on the dipstick.
turn creamy. The oil level will also have increased. If
the oil is emulsified, proceed to operation (5).
(2) Remove the fusible link that is positioned
third from the front of th e fusible link connection
block, located at the rear of the battery. Disconnect
the coil high tension lead from the coil. (3) Remove all of the spark plugs except one.
(4) Have an assistant operate the ignition switch
to rotate the engine and listen to the sound made by
the engine as it is being turned over. Move the spark
plug to a different cylinder and repeat the lest. By performing the same test on all cylinders, a
rough comparison can be made to determine if there
is any loss of compression in any cylinder. This will be
apparent by the different sound made by the engine as
it is being turned over.
Normally, if the compression is satisfactory the
cylinder with the spark plug installed will create a
resistance to the rotating engine.
However, if the compression is low in a particular
cylinder, the engine will tu rn over easily and smoothly
when that spark plug is in place.
(5) If the above checks show a loss of coolant
which is present in the engine oil or on the spark plug,
one or more of the following faults may be the cause:
Blown cylinder head gasket.
Cracked cylinder or cylinder head.
If the compression check showed any weak or
inconsistent compressions, in addition to the above
faults any of the following could also be the cause:
Broken piston{s)
Burnt or broken valve(s).
Provided the previous checks do not indicate an
View showing the location of the fusible links.
internal leakage of coolant, proceed with the follow-
ing:
(6) Remove the distributor cap and, with the aid
of an assistant operating th e starter motor, check that
the rotor arm rotates as the engine turns over. (7) Remove the camshaft hous ing top cover and.
again with an assistant operating the ignition switch,
check that all the valves open and close as the engine
turns over.
If the rotor arm or valves do not operate with
engine rotation, one of the following faults may be the
cause:
Rotor arm does not turn but valves operate:
Distributor drive shaft broken.
Rotor arm and valves do not operate: Broken
camshaft drive belt. Sheare d crankshaft timing gear
drive key. Sheared camshaft liming gear drive dowel.
Provided that all the previous checks have been
performed correctly and the operator is satisfied that
none of the components are at fault, all that remains
is for the ignition and valve timing to be checked. It
should be noted, however, that if loss of valve timing
proves to be the fault, th e cause of this occurrence
must be sought and rectified.
(8) In order to check the valve timing it will be
necessary to remove the distributor cap and the
camshaft housing top cover and turn the engine
clockwise via the crankshaft pulley until No. 1 piston
is at TDC on the compression stroke. In this position
the valves of No. 1 cylinder should be closed, the
valves of No. 4 should be rocking and the distributor
rotor should be pointing to the No. 1 high tension lead
segment in the distributor cap.
Engine 39
Oil pump cover plate screws............................ 6 Nm
Oil pump mounting bolts.................................. 6 Nm
Oil pump pickup bolts
(coat with Loctite 242)..................................... 8 Nm
Sump bolts (coat with Loctite 242) .................. 5 Nm
Sump drain plug .............................................. 35 Nm
*Use new bolts
Head bolts maximum torque 135 Nm
1. ENGINE MECHANICAL TROUBLE
SHOOTING
ENGINE MISSES AT IDLING SPEED
NOTE: For other causes of engine misfire,
refer to the Fuel and Engine Management
section.
(1) Blown head gasket: Check the cylinder com-
pressions and renew the he ad gasket as necessary.
(2) Burnt valves or seats in the cylinder head:
Check the cylinder compressions and overhaul the
cylinder head as necessary. (3) Broken or worn piston rings: Check the
cylinder compressions and renew the piston rings as
necessary.
(4) Weak or broken valve springs: Remove the
camshaft housing top cover and check the condition
of the valve springs. (5) Air leak at the inlet manifold gasket; Check
for air leaks by applying oil around the manifold
joints. Renew the gasket if an air leak is evident.
NOTE: Use a compre ssion gauge and check
the compression pressure in each cylinder as
described in the Engine Tune-up section. If
a low pressure reading is indicated in one or
more cylinders, remove the cylinder head for
gasket and valve inspection. Should the
gasket and valves prove satisfactory, inspect
the cylinder bores, pistons and rings.
Check for air leaks at the inlet manifold
by applying engine oil around the manifold
joints. If the oil can be seen or heard sucking
into the manifold or excessive smoke begins
to issue from the exhaust system, there is an
air leak at the inlet manifold.
NOISY VALVE OPERATION
(1) Faulty hydraulic tappets: Renew the faulty
tappet assemblies. (2) Weak or broken valve springs: Remove the
camshaft housing top cover and check the condition
of the valve springs. (3) Worn valve guides: Overhaul the cylinder
head as described in this section. (4) Worn rocker gear: Remove (he rocker gear
and check the components for wear.
Camshaft lobe wear is also a cause of noisy valve
operation.
BIG END BEARING NOISE
(1) Inadequate oil supply: Check the oil level in
the sump and the condition of the oil pump and relief
valve. Renew the oil filter.
(2) Excessive bearing clearance: Renew the bear-
ing shells, check and regrind the big end journals if
oval or tapered. (3) Thin oil or oil diluted by petrol or water:
Change to the correct oil grade. Check and rectify the
cause of the oil dilution. Ch eck that the engine is not
operating in overheat conditions.
(4) Low oil pressure: Check the engine oil level.
Check the pressure relief valve and spring and the oil
filter bypass valve. (5) Misaligned big end bearings: Align the con-
necting rods and renew the big end bearing shells.
NOTE: Big end bearing noise is indicated
by a metallic knock wh ich is usually loudest
at approximately 60 km/h with the throttle
Air leaks at the inlet manifold can be located by
applying engine oil around the suspect joints.