Maintenance - component location 1•5
1
3261 Jaguar XJ6
Front underbody view
1 Air conditioning compressor
2 Drivebelts
3 Anti-roll bar
4 Alternator
5 Lower radiator hose
6 Lower control arm
7 Steering gear boot
8 Steering gear
9 Engine sump drain plug
10 Exhaust system
11 Outer tie-rod end
Rear underbody view (typical)
1 Rear suspension control arms
2 Differential drain plug
3 Differential filler plug
(not visible)
4 Exhaust pipe
5 Driveshaft
6 Silencers
7 Handbrake cable
8 Fuel filter
1 General information
1This Chapter is designed to help the home
mechanic maintain his/her vehicle for safety,
economy, long life and peak performance.
2The Chapter contains a master
maintenance schedule, followed by Sections
dealing specifically with each task in the
schedule. Visual checks, adjustments,
component renewal and other helpful items
are included. Refer to the accompanying
illustrations of the engine compartment and
the underside of the vehicle for the locations
of the various components.
3Servicing your vehicle in accordance with
the mileage/time maintenance schedule and
the following Sections will provide a planned
maintenance programme, which should result
in a long and reliable service life. This is a
comprehensive plan, so maintaining some
items but not others at the specified service
intervals, will not produce the same results.
4As you service your vehicle, you will
discover that many of the procedures can -
and should - be grouped together, because of
the particular procedure being performed, or
because of the proximity of two otherwise-
unrelated components to one another. For
example, if the vehicle is raised for any
reason, the exhaust can be inspected at the
same time as the suspension and steering
components.
5The first step in this maintenance
programme is to prepare yourself before the
actual work begins. Read through all theSections relevant to the work to be carried out,
then make a list and gather all the parts and
tools required. If a problem is encountered,
seek advice from a parts specialist, or a dealer
service department.
2 Intensive maintenance
1If, from the time the vehicle is new, the
routine maintenance schedule is followed
closely, and frequent checks are made of fluid
levels and high-wear items, as suggested
throughout this manual, the engine will be
kept in relatively good running condition, and
the need for additional work will be minimised.
2It is possible that there will be times when
the engine is running poorly due to the lack of
regular maintenance. This is even more likely
if a used vehicle, which has not received
regular and frequent maintenance checks, is
purchased. In such cases, additional work
may need to be carried out, outside of the
regular maintenance intervals.
3If engine wear is suspected, a compression
test (refer to Chapter 2) will provide valuable
information regarding the overall performance
of the main internal components. Such a test
can be used as a basis to decide on the extent
of the work to be carried out. If, for example, a
compression test indicates serious internal
engine wear, conventional maintenance as
described in this Chapter will not greatly
improve the performance of the engine, and
may prove a waste of time and money, unless
extensive overhaul work is carried out first.4The following series of operations are those
which are most often required to improve the
performance of a generally poor-running
engine:
Primary operations
a) Clean, inspect and test the battery
(Section 6).
b) Check all the engine-related fluids (refer
to “Weekly checks”).
c) Check the condition and tension of the
auxiliary drivebelt (Section 21).
d) Renew the spark plugs (Section 16).
e) Inspect the distributor cap and rotor arm
(Section 19).
f) Check the condition of the air filter, and
renew if necessary (Section 17).
g) Renew the fuel filter (Section 18).
h) Check the condition of all hoses, and
check for fluid leaks (Section 7).
i) Check the exhaust gas emissions (see
Chapter 6).
5If the above operations do not prove fully
effective, carry out the following secondary
operations:
Secondary operations
All items listed under “Primary operations”,
plus the following:
a) Check the charging system (refer to
Chapter 5).
b) Check the ignition system (refer to
Chapter 5).
c) Check the fuel system (refer to Chapter 4).
d) Renew the distributor cap and rotor arm
(Section 19).
e) Renew the ignition HT leads (Section 19).
1•6Maintenance procedures
3261 Jaguar XJ6
Every 7500 miles (12 000 km) or 6 months
3 Engine oil and filter renewal
2
1Frequent oil changes are the best
preventive maintenance the home mechanic
can give the engine, because ageing oil
becomes diluted and contaminated, which
leads to premature engine wear.
2Make sure that you have all the necessary
tools before you begin this procedure (see
illustration). You should also have plenty of
rags or newspapers handy for mopping up
any spills.
3Access to the underside of the vehicle is
greatly improved if the vehicle can be lifted on
a hoist, driven onto ramps or supported by
axle stands.
4If this is your first oil change, get under the
vehicle and familiarise yourself with the
location of the oil drain plug. The engine and
3.2 These tools are required when
changing the engine oil and filter
1 Drain pan - It should be fairly shallow in
depth, but wide in order to prevent spills
2 Rubber gloves - When removing the drain
plug and filter, it is inevitable that you will
get oil on your hands (the gloves will
prevent burns)
3 Breaker bar - Sometimes the oil drain plug
is pretty tight and a long breaker bar is
needed to loosen it
4 Socket – To be used with the breaker bar
or a ratchet (must be the correct size to fit
the drain plug)
5 Filter wrench - This is a metal band-type
wrench, which requires clearance around
the filter to be effective
6 Filter wrench - This type fits on the bottom
of the filter and can be turned with a
ratchet or breaker bar (different size
spanners are available for different types of
filters)
hand tools to remove. Simply slide back the
locking collars and remove the inlet and outlet
fuel lines (see illustration). Detach the filter
mounting bracket and discard the old filter in
a proper container.
5Note the direction of the arrow on the
outside of the filter; it should be pointed
towards the front of the car. Make sure the
new filter is installed so that it’s facing the
proper direction. Note:Always refit new
copper washers where equipped.
6Refit the inlet and outlet fittings then tighten
the filter mounting bracket. Reconnect the
battery cable, start the engine and check for
leaks.
19 Ignition system check
2
1The spark plug leads should be checked
whenever new spark plugs are installed.
2Begin this procedure by making a visual
check of the spark plug leads while the engine
is running. In a darkened garage (make sure
there is adequate ventilation) start the engine
and observe each plug lead. Be careful not to
come into contact with any moving engine
parts. If there is a break in the lead, you will
see arcing or a small spark at the damaged
area. If arcing is noticed, make a note to
obtain new leads, then allow the engine to
cool and check the distributor cap and rotor.
3The spark plug leads should be inspected
one at a time to prevent mixing up the order,
which is essential for proper engine operation.
Each original plug lead should be numbered
to help identify its location. If the number is
illegible, a piece of tape can be marked with
the correct number and wrapped around the
plug lead.
4Disconnect the plug lead from the spark
plug. A removal tool can be used for this
purpose or you can grasp the rubber boot,
twist the boot half a turn and pull the boot
free. Do not pull on the lead itself.
5Check inside the boot for corrosion, which
will look like a white crusty powder.6Push the lead and boot back onto the end
of the spark plug. It should fit tightly onto the
end of the plug. If it doesn’t, remove the lead
and use pliers to carefully crimp the metal
connector inside the lead boot until the fit is
snug.
7Using a clean rag, wipe the entire length of
the lead to remove built-up dirt and grease.
Once the lead is clean, check for burns,
cracks and other damage. Do not bend the
lead sharply, because the conductor might
break.
8Disconnect the spark plug lead from the
distributor cap. Again, pull only on the rubber
boot. Check for corrosion and a tight fit.
Reinsert the lead in the distributor cap.
9Inspect the remaining spark plug leads,
making sure that each one is securely
fastened at the distributor and spark plug
when the check is complete.10If new spark plug leads are required,
purchase a set for your specific engine model.
Remove and replace the leads one at a time
to avoid mix-ups in the firing order.
11Detach the distributor cap by unsnapping
the cap retaining clips. Look inside it for
cracks, carbon tracks and worn, burned or
loose contacts (see illustrations).
12Pull the rotor off the distributor shaft and
examine it for cracks and carbon tracks (see
illustrations). Replace the cap and rotor if any
damage or defects are noted.
13It is common practice to refit a new cap
and rotor whenever new spark plug leads are
installed. When refitting a new cap, remove
the leads from the old cap one at a time and
attach them to the new cap in the exact same
location Note:If an accidental mix-up occurs,
refer to the firing order Specifications at the
beginning of this Chapter.
Every 15 000 miles or 12 months 1•15
1
19.11a Unsnap the distributor cap
retaining clips - pull the cap up and away
to access the rotor
19.11b Shown here are some of the
common defects to look for when
inspecting the distributor cap (typical cap
shown). If in doubt about its condition,
fit a new one
19.12a Pull off the rotor (arrowed) and
inspect it thoroughly
19.12b Check the ignition rotor for wear
and corrosion as indicated here (if in doubt
about its condition, buy a new one)
3261 Jaguar XJ6 18.3 Remove the banjo bolt from the
outlet side (B), detach the fitting from the
inlet side (A) and unscrew the filter
mounting bolt (C)
18.4 On 1991 to 1994 models, slide back
the locking collars and remove the inlet
and outlet fuel lines
13Allow the bellcrank to return to the idle
position and test the adjustment once again
until the correct adjustment has been attained.
11 Electronic Fuel Injection
(EFI) system-
general information
1These models are equipped with an
Electronic Fuel Injection (EFI) system. This fuel
injection system is designed by Bosch butlicensed by Lucas and is called the Lucas LH
Engine Management system. The EFI system
is composed of three basic sub systems: fuel
system, air induction system and electronic
control system (see illustration).
Fuel system
2An electric fuel pump is located on the
chassis of the rear suspension (external) (1988
to 1990) or inside the fuel tank (1991 to 1994)
The fuel pump supplies fuel under constant
pressure to the fuel rail, which distributes fuel
evenly to all injectors. From the fuel rail, fuel is
injected into the intake ports, just above the
intake valves, by fuel injectors. The amount of
fuel supplied by the injectors is precisely
controlled by an Electronic Control Unit (ECU).
A pressure regulator controls system pressure
in relation to intake manifold vacuum. A fuel
filter between the fuel pump and the fuel rail
filters fuel to protect the components of the
system.
Air induction system
3The air system consists of an air filter
housing, a Mass Air Flow (MAF) sensor
(airflow meter), Intake Air Temperature (IAT)
sensor and a throttle body. The MAF sensor is
an information gathering device for the ECU.A heated element determines the temperature
differential by measuring the current changes
which in turn measures the mass (weight and
volume) of air entering the engine. This
information helps the ECU determine the
amount of fuel to be injected by the injectors.
The throttle plate inside the throttle body is
controlled by the driver. As the throttle plate
opens, the amount of air that can pass
through the system increases, so the
potentiometer opens further and the ECU
signals the injectors to increase the amount of
fuel delivered to the intake ports. Refer to
Chapter 6 for additional information on the
fuel injection system sensors, test procedures
and renewal procedures.
Electronic control system
4The Computer Control System controls the
EFI and other systems by means of an
Electronic Control Unit (ECU), which employs
a microcomputer. The ECU receives signals
from a number of information sensors which
monitor such variables as intake air volume,
intake air temperature, coolant temperature,
engine rpm, acceleration/deceleration and
exhaust oxygen content. These signals help
the ECU determine the injection duration
necessary for the optimum air/fuel ratio. Some
Fuel and exhaust systems 4•9
4
10.11 Rotate the bellcrank until it reaches
wide open throttle and make sure the
pointer aligns with the A on the bellcrank.
Adjust if necessary
11.1 Fuel injection and emission control component locations for the 3.6 litre 1989 XJ6
3261 Jaguar XJ6 1 Fuel pressure regulator (under
fuel rail)
2 Idle Speed Control (ISC) motor
3 Fuel pressure damper4 Bellcrank
5 Throttle body (below bellcrank)
6 Intake Air Temp. (IAT) sensor
7 Supplementary air valve8 Mass Airflow (MAF) sensor
9 Throttle potentiometer (under
throttle body)
10 Fuel rail11 Fuel injector
13 Ignition amplifier (below block
valve)
14 Distributor