1994 JAGUAR XJ light

AJ16 Engine Service Manual
0 GENERAL DESCRIPTION - The engine is available as a 3,2 and 4,O liter unit. A 4,O liter supercharged version is also available. Fuel is supplied
to each cylinder via an injector fed from a regulated fuel rail. To comply with statutory regulations in some countries
and to reduce emissions during the warm
-up period, secondary air is delivered to the exhaust manifold by an electri- cally operated air injection pump. This improves oxidation until the catalytic converters are fully effective. All engine
functions are controlled by an integrated engine management system, which incorporates the on-board diagnostic
system (OBDII).
1.1 Construction
The skirted design crankcase is manufactured in cast aluminum alloy with shrink fit dry cast iron cylinder sleeves.
Thecrankshaft ismanufactured from cast
ironforthe3,2 literengine,forged steel forthe 4,O liter engineand is nitro-car-
burize treated to give a very high quality finish on the bearing surfaces and increase the life of the journals.
The crankshaft is supported by seven iron bearing caps having bearings, which are lead bronze on split steel backed
shells with a lead indium overlay.
Crankshaft end
-float is controlled by half thrust washers fitted on each side of the center main bearing journal. The
connecting rods are manufactured from carbon manganese steel, forged in an 'H' section. The small end bushes are
lead bronze with steel backing, machined to size after being pressed into the connecting rods. The connecting rod bear- ings are of a lead bronze alloy on split steel backed shells and with lead indium overlay.
The pistons are of monometal construction (aluminum) and have a spring assisted micro
-land oil control ring situated
below a barrel-faced internally tapered chrome plated compression ring and an externally stepped taper-faced second-
ary ring.
The cylinder head is cast from aluminum alloy with pent
-roof shaped combustion chambers with cross-flow valve
porting. Running directly in the cylinder head are
twocast iron camshafts retained by machined aluminumcaps. Each
camshaft uses chilled cams to drive two valves per cylinder via chilled cast iron bucket tappets with shim adjustment.
Control of each of the four valves per cylinder is maintained by single valve springs.
The camshafts are operated by a two stage 'duplex' chain drive from the crankshaft. Each stage is controlled by a hy
- draulic tensioner operating through a pivoted rubber-faced curved tensioner blade. The first stage incorporates a three
point drive via the crankshaft, intermediate shaft and auxiliary shaft. The intermediate shaft is live and provides a 0.75 x crank speed drive through the timing cover. This drive access is blanked off. The 'live' auxiliary shaft is driven at
crankshaft speed and is situated on the right hand side of the engine (looking from rear). In addition to driving the
engine position sensor via a set of 2 : 1 reduction spiral gears, it provides an external drive for the power assisted steer- ing pump at the rear. The second stage is a three point drive via the intermediate shaft and two camshafts. The 2:l reduction ratio from crank speed is achieved by the combined ratio of the intermediate and camshaft sprockets sizes.
The oil pump is a rotor
-type mounted on the underside of the front of the crankcase and driven by a 'simplex' chain
from the crankshaft nose. The pump incorporates a built-in pressure relief valve. Below the line of the crankcase, but
abovetheoil pan
oillevel aretwowindagetrays; these prevent oil beingsucked upand thrown into thecrankcasethere- by alleviating windage and power losses through oil surge.
At the rear of the crankshaft is
a new design of lip-type PTFE oil seal which provides a high degree of oil retention. It also allows the use of higher engine speeds and easier serviceability.
1.2 Cylinder Head Design
The four valves per cylinder are smaller in diameter than on a conventional two valve per cylinder engine and have a greater combined effective area. They are also lighter and apply less stress to the operating gear. The design in- creases the power at high engine speeds and allows an efficient combustion of the fuel. It also allows the spark plug
to besituated in its ideal central position which creates efficient combustion and consequently enhancesfuel economy.
1.3 Crankcase Breather
Blow-by gases are recycled via the air intake system to maintain a crankcase depression and so prevent their escape
to the atmosphere. A baffled vent from the camshaft cover is used for both full and part load breathing. For full load
breathing,
a connection is made direct to the clean side ofthe air filter upstream ofthe throttle disc. Part load breathing is provided by a spur off the full load pipe to downstream ofthe throttle disc via the water heated restrictor. In this way,
a crankcase depression is maintained at all throttle settings.
1.4 Lubrication System
Oil is drawn from the oil pan via a gauze filter. Pressurized oil, having been regulated by a relief valve, is then fed via
internal galleries on the left hand side of the cylinder block. Pressurized and filtered oil is fed into the main oil gallery,
the seven main bearings are fed and thence via crankshaft drillings to the connecting rod bearings. The intermediate
shaft, auxiliary shaft and camshaft bearings are pressure lubricated by means of internal drillings directly fed from the
front of the main oil gallery. For some markets an oil cooler is fitted to vehicles with
4,O liter supercharged engines.
The pistons run on hardened steel piston pins offset from the center line of the piston towards the thrust face.
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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
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AJ16 Engine Service Manual
= Refit the upper static damper assembly.
lighten the cylinder head bolts with reference to the se- quence shown in Fig. 1.
CAUTION: The cylinder head bolts MUST be renewed dur- ing assembly and torque tightened as de-
scribed in Section 2.1, SPS Joint Control
System.
Ensure that the camshaft is still on TDC using Ser
-
vice Tool 18G 1433 (1 Fig. 2).
Fit the harness clip and hose bracket to the cylinder head
front securing bolts.
Fit and tighten the front securing bolts.
1433 (1 Fig. 2).
b:
= Check the camshafts are set atTDC using Service Tool 18G
= Raise the timing chain from between the upper dampers.
Remove the elastic band.
= Fit and engage the sprockets to the chain and camshafts.
. Move all the chain free play to the tensioner side.
Fit upper chain tensioner tool 18G 1436/A (2 Fig. 3).
Fit and tighten the tool securing bolts (1 Fig. 3).
Tension the timing chain.
sprocket
(1 1 Fig. 4) and align the securing bolt holes.
bolts
(2 Fig. 4). Lock over the tabs.
Release the tension on the timing chain.
Re
-position the
chain over the camshafts.
. Remove the camshaft coupling (12 Fig. 4) from the
. Fit the tab washers (1 Fig. 4). Fit and tighten the securing
. Slacken off the upper chain tensioner tool securing bolts.
Remove the upper chain tensioner tool 18G 14361A (2 Fig.
Clean the tensioner assembly and gasket faces.
3).
Fit a new housing gasket (10 Fig. 4). Lubricate andfita new '0' ring (9 Fig. 4).
. Fit the tensioner to the cylinder head.
. Fit and tighten the tensioner assembly securing bolt
Clean the valve assembly and fit new '0' rings.
Using an Allen key, release the tensioner, ie turn the Allen
(4 Fig. 3).
Lubricate the tensioner valve.
key
anti-clockwise.
I
104 2 5 7 I l2
I Fig. 1
1
Fig. 2
Fig. 3
Fig. 4
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AJ16 Engine Service Manual
Note: No attempt should be made to clean up a burnt or
badly pitted valve face by extensive 'grinding in' of
the valve to the seat.
m Lightly lap the valves into the seats with a fine grinding
compound. The reseating operation should leave the fin- ished surfaces smooth. Excessive lapping will groove the
valve face resulting in a poor seat when the engine is hot.
A
- Correctly seated B - Undesirable condition C - Rectified condition
. Totestthe valvesforconcentricity withtheirseats,coatthe face of the valve with Prussian blue or similar, and rotate
the valve against the seat. If the valve face is concentric
with the valve stem, a mark will be made all around the
face. Should
a mark be made on only one side of the face,
the face is not concentric with the valve stem. Clean the
valve and again coat with Prussian blue and rotate the
valve against the seat.
. Check that the valve guide is concentric with the valve
seat,
if not, the seat must be re-cut. Whenever valves are
renewed the seats must be re-cut prior to lapping of the
valves. Check valve guide wear by inserting a new valve
into the guide to be checked,
lift it 6 mm from its seat and
rock it sideways.
. Movement of the valve across its seat (A Fig. 2) must not
exceed 0,04 to 0,07 mm. Should the movement exceed
this tolerance, the valve guide must be renewed. Ensure
that the relevant valve guide is selected prior to fitting.
. When new guides are to be fitted they should always be
one size larger than the old guide.
. Cylinder head bores will require reaming as follows: Re- move the old valve guide and ream the cylinder head to
the relevant dimension. Immerse the cylinder head in
boiling waterfor30 minutes. Coat the guide with graphite
grease, and drive in the guide from thecamshaft side until
the snap
-ring is seated in the groove.
b: The interference should not be sufficient to require
the use of excessive force when fitting the guide.
1 After fitting a valve guide, the valve seat must be recut using Service Tool MS 204 (Fig. 3). Examine the valveseat
inserts for pitting or excess wear. If renewal is necessary,
proceed as follows.
1 Remove the inserts by machining, leaving approximately 0,25 mm of metal which can easily be removed by hand
without damaging the cylinder head. Measure the diam- eter of the insert recess in the cylinder head. Grind down
the outside diameter of the new insert to a dimension 0,08
mm larger than the insert recess.
Heat the cylinder head for 30 minutes from cold to a tem- perature of 15OOC 1, Fit the insert ensuring that it beds
evenly in the recess. When the cylinder head has cooled,
re
-cut the valve seat using Service Tool MS 204. For cor- rect valve seat angles see Service Data in the Preliminary
Pages.
If new valve inserts have been fitted, the clearance
between valve stem and cam must be checked, see
Service Data in the Preliminary Pages.
. Fig. 1 shows:
U:
I
A
JIZ 2M
Fia. 2
Fig. 3
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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
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