1994 JAGUAR XJ spark plugs

AJ16 Engine Service Manual
SERVICE DATA
Engine Data
Application Item
Number of cylinders
Bore
Specification
Seneral 6
91
mm
Stroke 3,2 liter: 83 mm
4,O liter: 102 mm
3.2 liter: 3239 cm3
4.0 liter: 3980 cm3
Cubic capacity
Compression ratio
3.2 liter: 1O:l
4,O liter: 1O:l (normally aspirated)
4,O liter: 8,51 (supercharged)
1,5,3,6,2,4 (No. 1 cylinder at
crankshaft pulley end)
Fully mapped Lucas engine
management system with digital
ignition
Firing
order
gnition timing
0
0
0
Jalve clearance
Intake and exhaust 0,30 to 0,36 mm
Champion RCSYCC (except North
America, normally aspirated
engines)
Champion
RC12YCC (North
America, for normally aspirated
engines only)
__ ~ ~
--__ ~~
Spark
plug
0,9 mm
On-plug ignition coil
Diamond
Number per vehicle
Primary winding resistance
Current consumption ~ ~~
6
0,75 ohm
Oto6A
Clockwise
(viewed from above)
1,5,3,6,2,4 (No. 1 cylinder at
crankshaft pulley end)
-
Engine position sensor
Fuel injection equipment
Exhaust Emission Rotation
Firing order
Micro
-processor controlled engine
management system
Fuel pressure
Exhaust gas analyzer reading (at
engine idle speed, normal operating
temperature and with catalytic
converter fitted)
3 bar
0,5% CO maximum.
For Swiss market only:
0,02% CO
maximum,
70 ppm HC maximum
Idle speed (engine at normal
operating temperature) Manual transmission 700 RPM
Automatic
transmission 700 RPM (gear selector in neutral)
11,O to 11,7 bar (with all spark plugs
removed, throttle fully open, engine
at operating temperature and
a
minimum cranking speed of 300
RPM)
0,7 bar (maximum)
Compression pressure
Cylinder pressure
Differential pressure between
cylinders
Aluminum alloy
Cylinder block
. ___ Material
xiii
Issue 1 August 1994

AJ16 Engine Service Manual
FAULT DIAGNOSIS
3.1 Introduction
The following diagnostic procedures are provided to assist properly qualified persons to identify and rectify the faults
relating to the engine which are most likely to encountered. Reference is made to the Electrical Diagnostic Manual
(EDM), which should be consulted where necessary. Faults related to the cooling system are dealt with in Section 4.1
and to the fuel system in Section 5.1 in the appropriate Vehicle Service Manual (VSM).
3.2 Diagnostic Procedures
(fails to rotate)
I Engine rotates but 0 I will not fire
I
i
/Overheating
Overheating at tick-
Too cold
Loss of coolant Possible
Cause
Battery leads loose or ter
- minals corroded
Battery discharged
Starter motor inoperative
Starter motor speed too
low
Faulty ignition system
Fuel system defect
Oil requires changing
Worn crankshaft journals
Excessive crankshaft
end- float
Worn main bearing shells
Worn oil pump Oil pressure relief valve stick
- ing open
Oil pressure relief valve
spring too weak
Insufficient oil in oil pan
Engine overheating
Faulty gauge or sensor
Incorrect grade oil (viscosity
too low)
Water in oil Check
Check the condition of the
leads and terminals
Check condition of battery
with hydrometer
If the lights dim when ignition
switch is operated, the starter
may be jammed in starter
ring.
Check for loose and dirty con
- nections to the starter motor
Check battery leads and ter
- minals
Check state of battery charge
Refer to EDM
Remove the spark plugs
Check oil level and color
Listen for rumble or knock
Fit dial gauge and measure
Listen for rumble
Remove oil pump and check
the clearances
Remove valve and check for
sticking
Remove spring and check
spring rates
Check oil level
Refer to EDM
Check oil viscosity
Checkoil level and check if oil
is a milky white color
Check for leaking head gasket Remedy
Clean and tighten as necess
-
ary
Charge or renew battery as
necessary
Remove starter motor, free
off pinion and refit
Clean and tighten connec
- tions
Clean and tighten terminals
Charge or renew battery
as necessary
Rectify as required
Clean and re
-gap the spark
plugs, renew if worn out
Refer to Fuel System fault
finding in Section
5.1, VSM
Refer to Section
4.1, VSM
Refer to Section
4.1, VSM
Refer to Section
4.1, VSM
Refer to Section
4.1, VSM
Change oil and filter
Renew crankshaft
Renew thrust washers
Check crankshaft journals for
wear and renew shells
Renew oil pump
Renew valve
Renew spring
lop-up as required
Refer to Overheating fault
finding in Section
4.1, VSM
Rectify as required
Renew oil and filter
Renew oil and filter
Renew head gasket
Issue 1 August 1994 3

AJ16 Engine Service Manual
Symptom
Joisy chains
)etonation knock pinking)
.oss of power
Gugh running at iormal engine speed Possible
Cause
Low oil pressure
Tensioners not released
Chains worn
Sprockets worn
Tensioner worn
Ignition timing too far ad
- vanced
Head gasket leaking
Fuel
/ air mixture too weak
Engine running
too hot
Valve timing incorrect
Incorrect grade fuel
Burned valves Sticking valves
Poor engine tune
Insufficient valve clearance
Fuel injection fault
Lowcompression in cylinders
Ignition fault
Valve timing incorrect
Partial seizure of engine
Worn
camshaftb)
Incorrect grade fuel
Sticking valves Broken valve springs Piston fault
Leaking head gasket
Valve burned out
Valve seat burned out
Ignition fault
Fuel injection fault
Check
Take reading from oil pres- sure gauge when engine is
hot
Remove camshaft cover and
check tension of chain (top
chain). Remove timing cover
to check bottom chain tension
Visually check
/ remove and
check for wear
Visual check
Visual check
Refer to EDM
Check engine oil level and
checkfor contamination of oil
Pressure test cooling system
and check for contamination
of coolant in header tank
Refer to EDM
Check valve timing
If all other checks
OK, this
could be the cause
Check cylinder compressions
Check cylinder compressions
Refer to EDM
Check valve clearance
Check compressions
Refer to EDM
Check valve timing
Remove spark plugs and ro
- tate crankshaft
Remove
camshaft(s) and
check for wear
If all other checks OK this
could be the cause
Check cylinder compressions
Check cylinder compressions
and for bent valve stems
Check cylinder cornpressions
Check cylinder compressions
Check cylinder compressions
Refer to
EDM
Remedy
Refer to Insufficient Oil Pres- sure fault finding
Insert
3 mm Allen key and
turn tensioner anti-clock- wise, compress tensioner to
release bottom chain
Renew as necessary
Renew as necessary
Renew as necessary
Rectify as required
Renew head gasket
Rectify
as required
Refer
to Overheating fault
finding in Section 4.1, VSM
Adjust valve timing
Drain fuel tank and refill with
correct grade fuel
Remove cylinder head and
renew valves
Remove cylinder head and
renew valves
/ guides or
springs
Rectify as required
Adjust as necessary
Refer to Fuel System fault
finding in Section 5.1, VSM
Rebore
1 re-ring as necessary
Rectify as required
Adjust valve timing
Overhaul engine as required
Renew
camshaft(s)
Drain fuel tank and refill with
correct grade fuel
Renew valve, springs or
guides
Renew valve springs and
valves as required
Renew pistons
Refer to Detonation Knock
fault finding
Renew valve
Re
-cut or renew valve seat
Rectify as required
Refer to Fuel System fault
Tindim in Section 5.1, VSM
issue 1 August 1994 5

AJ16 Engine Service Manual
4.2 Camshaft Cover Gasket, Renew
SRO 12.29.39
1 Remove the top cover and disconnect the on-plug coils
from the spark plugs.
. Disconnect the camshaft cover breather hose.
1 Remove the camshaft cover to cylinder head securing
Screws (1 Fig. 11, and remove the camshaft cover (2 Fig. 1).
. Remove and discard the camshaft cover gasket (3 Fig. 1).
. Clean the camshaft cover and cylinder head mating faces.
1 Fit a new gasket to the camshaft cover.
. Refit the camshaft cover.
1 Fit and tighten the camshaft cover securing screws.
. Reconnect the breather hose.
1 Reconnect the on-plug coils to the spark plugs and fit the
top cover.
I Fia. I
Issue 1 August 1994 9

AJ16 Engine Service Manual
4.5 Cylinder Head, Overhaul
SRO 12.29.19
1 Remove the cylinder head, see Section 4.4.
1 Place the cylinder head on suitable blocks on a bench.
1 Remove the spark plugs and the intake and exhaust mani-
folds.
1 Mark the position of the camshaft caps relative to the
head, remove the cap securing bolts and remove the caps
(1 Fig. 1).
1 Remove the camshafts.
. Using a magnet, lift out the cam followers (1 Fig. 2).
1 Remove the valve springs, using Service Tool MS 1519A,
1 Retrieve the collars, collets and spring retaining plates.
1 Remove the valves, noting the relationship between valve
and guide to ensure correct pairing during re-assembly.
* Remove the seals from the intake valve guides and re- move the cylinder head rear blanking plate.
1 Clean all component parts.
1 Check for wear and burning of valves or seats.
1 Check the cylinder head face for distortion.
1 If distortion is evident, a maximum of 0,25 mm may be re- moved by skimming the cylinder head.
1 Taking care not to damage the inside surface of the com-
bustion chambers, clean the intake and exhaust ports.
CAUTION: When using scrapers or wire brushes for re- moving carbon deposits, avoid scratching the
valve faces and seats. A soft wire brush is the most suitable implement for this purpose.
1 Clean all carbon and other deposits from the valve guide
using a suitable valve guide brush. Thoroughly wash the
cylinder head to ensure that all loose carbon is removed
and dry the cylinder head with a high pressure air line.
. After cleaning and polishing each valve, examine the
stems for straightness and wear, using a suitable dial
gauge and vee
-block see example at Fig. 3.
1 Examine the valve faces for burns, pitting and distortion.
Renew any valves that are excessively worn, bent, or too
badly pitted to be salvaged by refacing.
Support the
valves using a wooden block.
valve spring compressor.
/ 112 310
Fig. 1
Fia. 2
I
JlZ 268
Fia. 3 I " 1
Issue 1 August 1994 16

0 4.6 Cylinder Head Casting, Renew
SRO 12.29.15
1 Remove the cylinder head, see Section 4.4.
1 Place the cylinder head on suitable blocks on a bench.
1 Remove the spark plugs.
1 Remove the intake valve camshaft cap securing bolts.
1 Remove the camshaft caps.
1 Remove the camshaft.
1 Repeat the procedure for the exhaust camshaft.
1 Remove the cam followers and shims, noting the posi-
1 Remove the valves using Service Tool MS 1519A valve
1 Remove the seals from the intake valve guides.
1 Remove the rear blanking plate.
1 Clean all components and examine for wear and damage.
Renew any worn or damaged parts as necessary.
1 Clean thoroughly the new cylinder head casting.
1 Refit the rear blanking plate to the new cylinder head.
0 1 Smearfinegrindingcompound on tothe face ofonevalve.
1 Oil the valve stem.
1 Fit the valve to the head.
1 Lightly lap the valves into the seats, leaving a smooth fin-
ish to both surfaces.
Note: Excessive lapping will groove the valve face, result- ing in poor seating when hot.
1 Clean the valve and seat.
1 Repeat the procedure for the remaining valves.
1 Fit a new seal to the intake valve guide.
1 Lubricate the valve stem. Fit the valve to the guide. Fit the
. Fit Service Tool MS 1519A spring compressor to the valve.
1 Compress the valve spring, fit and seat the collets, and re- lease the clamp.
1 Repeat the procedure for the remaining valves.
. Refit the shims.
1 Ensure that the shims are seated correctly.
1 Lubricate and fit the cam followers (Fig. 1).
. Lubricate the camshafts and bearings.
1 Fit the camshafts.
1 Fit the camshaft caps.
1 Fit and torque tighten the camshaft cap securing bolts.
. Measure the valve clearance between the heel of the cam
and the cam follower (Fig.
21, turning the camshaft as
necessary to measure all the clearances, see Section 4.3.
Afinal check of the valveclearancesshould be done
when the cylinder head is fitted and torque tigh- tened to the cylinder block.
1 Clean the cylinder head thoroughly and check the cylinder
head and cylinder block for warping, bowing or cracks.
Renew if necessary.
tions
for re
-assembly.
spring compressor.
spring seat, spring and collar.
Note:
1 Fit a new cylinder head gasket.
1 Fit the cylinder head assembly, see Section 4.4.
I II
Fig. 1
JI1 U4
Fig. 2
Issue 1 August 1994 19