1997 JAGUAR XJ6 Chapter 12

6Refit the compression gauge in the spark
plug hole (see illustration).
7Crank the engine over at least seven
compression strokes and watch the gauge.
The compression should build up quickly in a
healthy engine. Low compression on the first
stroke, followed by gradually increasing
pressure on successive strokes, indicates
worn piston rings. A low compression reading
on the first stroke, which doesn’t build up
during successive strokes, indicates leaking
valves or a blown cylinder head gasket (a
cracked cylinder head could also be the
cause). Deposits on the undersides of the
valve heads can also cause low compression.
Record the highest gauge reading obtained.
8Repeat the procedure for the remaining
cylinders and compare the results to this
Chapter’s Specifications.
9Add some engine oil (about three squirts
from a plunger-type oil can) to each cylinder,
through the spark plug hole, and repeat the
test.
10If the compression increases after the oil
is added, the piston rings are definitely worn.
If the compression doesn’t increase
significantly, the leakage is occurring at the
valves or cylinder head gasket. Leakage past
the valves may be caused by burned valve
seats and/or faces or warped, cracked or bent
valves.
11If two adjacent cylinders have equally low
compression, there’s a strong possibility that
the cylinder head gasket between them is
blown. The appearance of coolant in the
combustion chambers or the crankcase
would verify this condition.
12If one cylinder is 20 percent lower than the
others, and the engine has a slightly rough
idle, a worn exhaust lobe on the camshaft
could be the cause.
13If the compression is unusually high, the
combustion chambers are probably coated
with carbon deposits. If that’s the case, the
cylinder head(s) should be removed and
decarbonised.
14If compression is way down or varies
greatly between cylinders, it would be a goodidea to have a leak-down test performed by
an automotive repair workshop. This test will
pinpoint exactly where the leakage is
occurring and how severe it is.
5 Engine removal-
methods and precautions
If you’ve decided that an engine must be
removed for overhaul or major repair work,
several preliminary steps should be taken.
Locating a suitable place to work is
extremely important. Adequate work space,
along with storage space for the vehicle, will
be needed. If a workshop or garage isn’t
available, at the very least a flat, level, clean
work surface made of concrete or asphalt is
required.
Cleaning the engine compartment and
engine before beginning the removal
procedure will help keep tools clean and
organised.
An engine hoist or A-frame will also be
necessary. Make sure the equipment is rated
in excess of the combined weight of the
engine and transmission. Safety is of primary
importance, considering the potential hazards
involved in lifting the engine out of the vehicle.
If the engine is being removed by a novice,
a helper should be available. Advice and aid
from someone more experienced would also
be helpful. There are many instances when
one person cannot simultaneously perform all
of the operations required when lifting the
engine out of the vehicle.
Plan the operation ahead of time. Arrange
for or obtain all of the tools and equipment
you’ll need prior to beginning the job. Some of
the equipment necessary to perform engine
removal and refitting safely and with relative
ease are (in addition to an engine hoist) a
heavy duty trolley jack, complete sets of
spanners and sockets as described in the
front of this manual, wooden blocks and
plenty of rags and cleaning solvent for
mopping up spilled oil, coolant and petrol. If
the hoist must be rented, make sure that you
arrange for it in advance and perform all of the
operations possible without it beforehand.
This will save you money and time.
Plan for the vehicle to be out of use for
quite a while. A machine workshop will be
required to perform some of the work which
the do-it-yourselfer can’t accomplish without
special equipment. These shops often have a
busy schedule, so it would be a good idea to
consult them before removing the engine in
order to accurately estimate the amount of
time required to rebuild or repair components
that may need work.
Always be extremely careful when removing
and refitting the engine. Serious injury can
result from careless actions. Plan ahead, take
your time and a job of this nature, although
major, can be accomplished successfully.
6 Engine- removal and refitting
3
Note:Read through the entire Section before
beginning this procedure. It is recommended
to remove the engine and transmission from
the top as a unit, then separate the engine
from the transmission on the workshop floor. If
the transmission is not being serviced, it is
possible to leave the transmission in the
vehicle and remove the engine from the top by
itself, by removing the crankshaft damper and
tilting up the front end of the engine for
clearance,but access to the upper
bellhousing bolts is only practical when the
rear transmission mount and driveshaft have
been removed and the transmission is angled
down with a trolley jack.
Removal
1Relieve the fuel system pressure (see
Chapter 4).
2Disconnect the battery negative cable.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
3Place protective covers on the wings and
cowl and remove the bonnet (see Chapter 11).
4Remove the battery and battery tray.
5Remove the air cleaner assembly (see
Chapter 4).
6Raise the vehicle and support it securely on
axle stands. Drain the cooling system and
engine oil and remove the drivebelts (see
Chapter 1).
7Clearly label, then disconnect all vacuum
lines, coolant and emissions hoses, wiring
harness connectors and earth straps.
Masking tape and/or a touch up paint
applicator work well for marking items (see
illustration). Take instant photos or sketch
the locations of components and brackets.
8Remove the cooling fan(s) and radiator (see
Chapter 3).
9Disconnect the heater hoses.
10Release the residual fuel pressure in the
tank by removing the petrol cap, then detach
the fuel lines connecting the engine to the
chassis (see Chapter 4). Plug or cap all open
fittings.
2B•4 Engine removal and overhaul procedures
4.6 A compression gauge with a threaded
fitting for the spark plug hole is preferred
over the type that requires hand pressure
to maintain the seal - be sure to block
open the throttle valve as far as possible
during the compression check!
6.7 Label both ends of each wire and hose
before disconnecting it
3261 Jaguar XJ6

11Disconnect the throttle linkage,
transmission linkage (and dipstick tube) and
speed control cable, if equipped, from the
engine (see Chapters 4 and 7).
12Refer to Part A of this Chapter and
remove the intake and exhaust manifolds.
13Unbolt the power steering pump (see
Chapter 10). Tie the pump aside without
disconnecting the hoses. Refer to Part A for
removal of the hydraulic pump (if equipped)
from the timing chain cover.
14On air-conditioned models, unbolt the
compressor and set it aside. Do not
disconnect the refrigerant hoses. Note:Wire
the compressor out of the way with a coat
hanger, don’t let the compressor hang on the
hoses.
15Refer to Part A of this Chapter and
remove the drivebelts, water pump pulley and
crankshaft pulley.
16Attach a lifting sling to the engine.
Position a hoist and connect the sling to it.
Take up the slack until there is slight tension
on the hoist.
17With a trolley jack and piece of wood
supporting the bottom of the transmission
sump, refer to Chapter 8 and remove the
driveshaft and rear transmission mount.
Warning: Do not place any part
of your body under the
engine/transmission when it’s
supported only by a hoist or
other lifting device.
18With the hoist taking the weight of the
engine, unbolt the engine mounts (see Part A
of this Chapter).
19Recheck to be sure nothing is still
connecting the engine or transmission to the
vehicle. Disconnect and label anything still
remaining.
20Slowly lift the engine/transmission out of
the vehicle (see illustration). It may be
necessary to pry the mounts away from the
frame brackets.21Move the engine away from the vehicle
and carefully lower the hoist until the
engine/transmission can be set on the floor.
Refer to Chapter 7 and remove the
transmission and converter. Refer to Part A of
this Chapter for removal of the flywheel. With
the flywheel removed, remove the four large
bolts and the transmission adapter plate from
the engine (see illustration).
22Refer to Part A of this Chapter for removal
of the rear main seal retainer plate from the
back of the engine, then lift the engine to a
position where it can be attached to a sturdy
engine stand.
Refitting
23Check the engine/transmission mounts. If
they’re worn or damaged, renew them.
24Attach the hoist and remove the engine
from the stand. Refer to Part A of this Chapter
and renew the rear main seal and retainer
plate, then reattach the transmission adapter
plate and refer to Chapter 7 for mounting the
converter and transmission.
25Carefully lower the engine into the vehicle
with the hoist. An assistant is helpful to guide
the engine clear of accessories in the engine
compartment as the engine is lowered into
place.
26Refit the engine mount bolts and tighten
them securely. Raise the back of the
transmission with the trolley jack and reattach
the transmission mount, driveshaft and shift
linkage.
27Refit the remaining components and
fasteners in the reverse order of removal.
28Add coolant, oil, power steering and
transmission fluids as needed (see Chapter 1).
29Run the engine and check for proper
operation and leaks. Shut off the engine and
recheck the fluid levels.
7 Engine rebuilding
alternatives
The do-it-yourselfer is faced with a number
of options when performing an engine
overhaul. The decision to renew the engine
block, piston/connecting rod assemblies and
crankshaft depends on a number of factors,
with the number one consideration being the
condition of the engine block. Other
considerations are cost, access to machine
workshop facilities, parts availability, time
required to complete the project and the
extent of prior mechanical experience on the
part of the do-it-yourselfer.
Some of the rebuilding alternatives include:
Individual parts- If the inspection
procedures reveal that the engine block and
most engine components are in reusable
condition, purchasing individual parts may be
the most economical alternative. The engine
block, cylinder head, crankshaft, and
piston/connecting rod assemblies should all
be inspected carefully. Even if the engine
block shows little wear, the cylinder bores
should be surface honed.
Short block- A short block consists of an
engine block with a crankshaft and
piston/connecting rod assemblies already
installed. All new bearings are incorporated
and all clearances will be correct. The existing
camshafts, valve train components, cylinder
head and external parts can be bolted to the
short block with little or no machine workshop
work necessary.
Long block- A long block consists of a
short block plus an oil pump, sump, cylinder
head, valve cover, camshaft and valve train
components, timing sprockets and chain or
gears and timing cover. All components are
installed with new bearings, seals and gaskets
Engine removal and overhaul procedures 2B•5
2B
3261 Jaguar XJ6 6.20 Lift the engine high enough to clear the vehicle, tilting it up
at the front to clear the front crossmember, then move it away
and lower the hoist
6.21 With the engine on the floor but still supported by the hoist,
remove the four large bolts (arrowed) and pull off the
transmission adapter plate

done during the engine overhaul. Note:If the
engine was severely overheated, the cylinder
head is probably warped (see paragraph 12).
Cleaning
2Scrape all traces of old gasket material and
sealing compound off the cylinder head
gasket, intake manifold and exhaust manifold
sealing surfaces. Be very careful not to gouge
the cylinder head. Special gasket-removal
solvents that soften gaskets and make
removal much easier are available at car
accessory outlets.
3Remove all built up scale from the coolant
passages.
4Run a stiff wire brush through the various
holes to remove deposits that may have
formed in them. If there are heavy deposits in
the water passages, the bare head should be
professionally cleaned at a machine
workshop.
5Run an appropriate-size tap into each of the
threaded holes to remove corrosion and
any thread sealant that may be present. If
compressed air is available, use it to clear the
holes of debris produced by this operation.
Warning: Wear eye protection
when using compressed air!
6Clean the exhaust and intake manifold stud
threads with a wire brush.
7Clean the cylinder head with solvent and dry
it thoroughly. Compressed air will speed the
drying process and ensure that all holes and
recessed areas are clean. Note:Decarbonising
chemicals are available and may prove very
useful when cleaning cylinder heads and valve
train components. They are very caustic and
should be used with caution. Be sure to follow
the instructions on the container.
8Clean the lifters with solvent and dry themthoroughly. Compressed air will speed the
drying process and can be used to clean out
the oil passages. Don’t mix them up during
cleaning - keep them in a box with numbered
compartments.
9Clean all the valve springs, spring seats,
keepers and retainers with solvent and dry
them thoroughly. Work on the components
from one valve at a time to avoid mixing up
the parts.
10Scrape off any heavy deposits that may
have formed on the valves, then use a
motorised wire brush to remove deposits from
the valve heads and stems. Again, make sure
that the valves don’t get mixed up.
Inspection
Note:Be sure to perform all of the following
inspection procedures before concluding that
machine workshop work is required. Make a
list of the items that need attention. The
inspection procedures for the lifters and
camshafts, can be found in Part A.
Cylinder head
11Inspect the cylinder head very carefully for
cracks, evidence of coolant leakage and other
damage. If cracks are found, check with an
automotive machine workshop concerning
repair. If repair isn’t possible, a new cylinder
head should be obtained.
12A common problem on aluminium engines
is erosion of the cylinder head or engine block
coolant passages due to improper sealing.
Using a new cylinder head gasket held
against the cylinder head, trace the bolt holes
and coolant passage outlines in pencil on the
cylinder head. Use the gasket to trace the
same on the top of the engine block (see
illustration). If the top of the engine block has
eroded outsideof the pattern around thewater passages or cylinder head bolt holes,
the engine block must be renewed; the
manufacturer doesn’t recommend resurfacing
it. If the cylinder head has eroded outside of
the water passage holes but the erosion is
away fromthe combustion chamber, the
eroded area can be built up with metal-
impregnated epoxy and machined flat again.
13Using a straightedge and feeler gauge,
check the cylinder head gasket mating
surface (on the engine block and cylinder
head) for warpage (see illustration). If the
warpage exceeds the limit found in this
Chapter’s Specifications, it can be resurfaced
at an automotive machine workshop, but no
more then 0.010-inch of material should be
removed. If the cylinder head had been
overheated, take it to the machinist for
inspection before proceeding further. It’s
possible that the overheating could have
annealed (softened) the aluminium of the
cylinder head, making it unsuitable for
machine work. In this case, a new cylinder
head is required.
Note 1:To check if a cylinder head has been
machined previously, measure the height
between the cylinder head gasket surface and
the valve cover mounting surface with a large
micrometer or vernier caliper and compare
with Specifications.
Note 2:Jaguar aluminium cylinder heads
require precision machine work. It is best to
find a machine workshop that has
considerable experience in servicing Jaguar
cylinder heads.
14Examine the valve seats in each of the
combustion chambers. If they’re pitted,
cracked or burned, the cylinder head will
require valve service that’s beyond the scope
of the home mechanic.
Engine removal and overhaul procedures 2B•7
2B
3261 Jaguar XJ6 10.12 Place the new head gasket on the engine block, and trace
around the water passages and bolt holes - make sure there is no
erosion of the aluminium beyond these lines
10.13 Check the cylinder head and engine block gasket surfaces
for warpage by trying to slip a feeler gauge under a precision
straightedge (see the Specifications for the maximum warpage
allowed and use a feeler gauge of that thickness) - check both the
cylinder head and engine block (shown)

15Check the valve stem-to-guide clearance
with a small hole gauge and micrometer, or a
small dial bore gauge (see illustration). Also,
check the valve stem deflection with a dial
indicator attached securely to the cylinder
head. The valve must be in the guide and
approximately 1/16-inch off the seat. The total
valve stem movement indicated by the gauge
needle must be noted, then divided by two to
obtain the actual clearance value. If it exceeds
the stem-to-guide clearance limit found in this
Chapter’s Specifications, the valve guides
should be renewed. After this is done, if
there’s still some doubt regarding the
condition of the valve guides they should be
checked by an automotive machine workshop
(the cost should be minimal).
Valves
16Carefully inspect each valve face for
uneven wear, deformation, cracks, pits and
burned areas. Check the valve stem for
scuffing and galling and the neck for cracks.
Rotate the valve and check for any obvious
indication that it’s bent. Look for pits and
excessive wear on the end of the stem. The
presence of any of these conditions indicates
the need for valve service by an automotive
machine workshop.
17Measure the margin width on each valve
(see illustration). Any valve with a margin
narrower than 1/32-inch will have to be
replaced with a new valve.
Valve components
18Check each valve spring for wear (on the
ends) and pits. Measure the free length and
compare it to this Chapter’s Specifications
(see illustration). Any springs that are shorter
than specified have sagged and should not be
re-used. The tension of all springs should be
pressure checked with a special fixture before
deciding that they’re suitable for use in a
rebuilt engine (take the springs to an
automotive machine workshop for this check).
Note:If any valve springs are found broken on
1988 or 1989 engines, all springs should be
replaced with the improved springs used in
1990 (after VIN 9EPCLA120245) and later
engines. They are identified with a white
stripe. If your engine has springs with white-
stripes, they have already been replaced, and
only broken ones need be replaced.
19Stand each spring on a flat surface and
check it for squareness (see illustration). If
any of the springs are distorted or sagged,
renew all of the springs.
20Check the spring retainers and keepers
for obvious wear and cracks. Any
questionable parts should be renewed, as
extensive damage will occur if they fail during
engine operation.
21If the inspection process indicates that the
valve components are in generally poor
condition and worn beyond the limits specified,
which is usually the case in an engine that’s
being overhauled, reassemble the valves in the
cylinder head and refer to Section 11 for valve
servicing recommendations.
11 Valves- servicing
5
1Because of the complex nature of the job
and the special tools and equipment needed,
servicing of the valves, the valve seats and the
valve guides, commonly known as a valve job,
should be done by a professional.
2The home mechanic can remove and
dismantle the cylinder head(s), do the initial
cleaning and inspection, then reassemble and
deliver them to a dealer service department or
an automotive machine workshop for the
actual service work. Doing the inspection will
enable you to see what condition the cylinder
head(s) and valvetrain components are in and
will ensure that you know what work and new
parts are required when dealing with an
automotive machine workshop.
3The dealer service department, or
automotive machine workshop, will remove
the valves and springs, will recondition or
renew the valves and valve seats, recondition
the valve guides, check and renew the valve
springs, spring retainers and keepers (as
necessary), replace the valve seals with new
ones, reassemble the valve components and
make sure the installed spring height is
correct. The cylinder head gasket surface will
also be resurfaced if it’s warped.
4After the valve job has been performed by a
professional, the cylinder head(s) will be in like
new condition. When the cylinder heads are
returned, be sure to clean them again before
refitting on the engine to remove any metal
particles and abrasive grit that may still be
present from the valve service or cylinder
head resurfacing operations. Use compressed
air, if available, to blow out all the oil holes and
passages.
12 Cylinder head- reassembly
2
1Regardless of whether or not the cylinder
head was sent to an automotive machine
workshop for valve servicing, make sure it’s
clean before beginning reassembly. Renew
the cylinder head rear plate gasket any time
that the engine is overhauled or the cylinder
head is reconditioned (see Part A of this
Chapter for renewal procedure).
2If the cylinder head was sent out for valve
servicing, the valves and related components
will already be in place. Begin the reassembly
procedure with paragraph 8.
3Refit new seals on each of the valve guides.
Gently push each valve seal into place until
it’s seated on the guide.
Caution: Don’t hammer on the valve seals
once they’re seated or you may damage
them. Don’t twist or cock the seals during
refitting or they won’t seat properly on the
valve stems.
2B•8 Engine removal and overhaul procedures
10.15 Use a small dial bore gauge to
determine the inside diameter of the valve
guides - subtract the valve stem diameter
to determine the stem-to-guide clearance10.17 The margin width on each valve
must be as specified (if no margin exists,
the valve cannot be re-used)
10.18 Measure the free length of each
valve spring with a dial or vernier caliper10.19 Check each valve spring for
squareness
3261 Jaguar XJ6

4Beginning at one end of the cylinder head,
lubricate and refit the first valve. Apply moly-
base grease or clean engine oil to the valve
stem.
5Place the spring seat or shim(s) over the
valve guide and set the valve spring and
retainer in place.
6Compress the springs with a valve spring
compressor and carefully refit the keepers in
the upper groove, then slowly release the
compressor and make sure the keepers seat
properly. Apply a small dab of grease to each
keeper to hold it in place if necessary (see
Haynes Hint).
7Repeat the procedure for the remaining
valves. Be sure to return the components to
their original locations - don’t mix them up!
13 Pistons/connecting rods-
removal
4
Note :Prior to removing the piston/connecting
rod assemblies, remove the cylinder head(s),
the sump and the oil pump transfer tubes by
referring to Chapter 2A.
1Use your fingernail to feel if a ridge has
formed at the upper limit of ring travel (about
1/4-inch down from the top of each cylinder).
If carbon deposits or cylinder wear have
produced ridges, they must be completely
removed with a special tool (see illustration).
Follow the manufacturer’s instructions
provided with the tool. Failure to remove the
ridges before attempting to remove the
piston/connecting rod assemblies may result
in piston damage.
2After the cylinder ridges have been
removed, turn the engine upside-down so the
crankshaft is facing up. Remove the screws
and the front and rear baffle plates from the
bottom of the engine block (see illustration).
3Before the connecting rods are removed,
check the endplay with a feeler gauge. Slide
the blade between the first connecting rod
and the crankshaft throw until the play is
removed (see illustration). The endplay is
equal to the thickness of the feeler gauge(s). If
the endplay exceeds the specified service
limit, new connecting rods will be required. Ifnew rods (or a new crankshaft) are installed,
the endplay may fall under the service limit (if
it does, the rods will have to be machined to
restore it - consult an automotive machine
workshop for advice if necessary). Repeat the
procedure for the remaining connecting rods.
4Check the connecting rods and caps for
identification marks. If they aren’t plainly
marked, use a small centre punch to make the
appropriate number of indentations on each rod
and cap (1, 2, 3, etc, depending on the cylinder
they’re associated with) (see illustration).
5Loosen each of the connecting rod cap nuts
1/2-turn at a time until they can be removed by
hand. Remove the number one connecting rod
cap and bearing insert. Don’t drop the bearing
insert out of the cap. Note:These engines use
special connecting rod and main bearing cap
bolts that are designed to be used one time
only. They can be used during Plastigage
checks, but must be replaced with new bolts
when the engine is finally reassembled.
6Slip a short length of plastic or rubber hose
over each connecting rod cap bolt to protect
the crankshaft journal and cylinder wall as the
piston is removed (see illustration).
7Remove the bearing insert and push the
connecting rod/piston assembly out through
the top of the engine. Use a wooden hammer
handle to push on the upper bearing surface
in the connecting rod. If resistance is felt,
double-check to make sure that all of the
ridge was removed from the cylinder.
Engine removal and overhaul procedures 2B•9
2B
13.2 Remove the screws (arrowed) and
remove the front and rear baffle plates13.3 Check the connecting rod side
clearance with a feeler gauge as shown
13.4 The connecting rods and caps should
be marked by cylinder number - if they
aren’t, mark them with a centre punch to
avoid confusion during reassembly13.6 To prevent damage to the crankshaft
journals and cylinder walls, slip sections of
hose over the connecting rod bolts before
removing the pistons
3261 Jaguar XJ6 13.1 A ridge reamer is required to remove
the ridge from the top of each cylinder -
do this before removing the pistons!
The keepers are easier to fit if a small
amount of grease is applied to keep
them in place

8Repeat the procedure for the remaining
cylinders. Note:Turn the crankshaft as
needed to position the piston/connecting rod
assembly to be removed close to parallel with
the cylinder bore - i.e. don’t try to drive it out
while at a large angle to the bore.
9After removal, reassemble the connecting
rod caps and bearing inserts in their
respective connecting rods and refit the cap
nuts/bolts finger tight. Leaving the old bearing
inserts in place until reassembly will help
prevent the big-end bearing surfaces from
being accidentally nicked or gouged.
10Don’t separate the pistons from the
connecting rods (see Section 18 for additional
information).
14 Crankshaft- removal
3
Note:The rear main oil seal and retainer must
be removed from the engine block before
proceeding with crankshaft removal (see Part
A of this Chapter).
1Before the crankshaft is removed, check
the endplay. Mount a dial indicator to the front
of the engine with the stem in line with, and
just touching, the end of the crankshaft (see
illustration).2Push the crankshaft all the way to the rear
and zero the dial indicator. Next, pry the
crankshaft to the front as far as possible and
check the reading on the dial indicator. The
distance that it moves is the endplay. If it’s
greater than that specified in this Chapter’s
Specifications, check the crankshaft thrust
surfaces for wear. If no wear is evident, new
thrust washers should correct the endplay.
3If a dial indicator isn’t available, feeler
gauges can be used. Gently pry or push the
crankshaft all the way to the front of the
engine. Slip feeler gauges between the
crankshaft and the front face of the number 4
(thrust) main bearing to determine the
clearance (see illustration).
4Check the main bearing caps to see if
they’re marked to indicate their locations.
They should be numbered consecutively from
the front of the engine to the rear. If they
aren’t, mark them with number stamping dies
or a centre punch. Main bearing caps
generally have a cast-in arrow, which points
to the front of the engine. Loosen the main
bearing cap bolts 1/4-turn at a time each,
stating at the ends and working toward the
centre, until they can be removed by hand.
5The main bearing caps are numbered on
the right side with corresponding numbers
stamped into the sump rail on the same side
(see illustration). Gently tap the caps with asoft-face hammer, then separate them from
the engine block. If necessary, use the bolts
as levers to remove the main bearing caps.
Try not to drop the bearing inserts if they
come out with the caps. Note:The number
four main bearing is the thrust bearing and is
not numbered.
6Carefully lift the crankshaft out of the
engine. It may be a good idea to have an
assistant available, since the crankshaft is
quite heavy. With the bearing inserts in place
in the engine block and main bearing caps,
return the main bearing caps to their
respective locations on the engine block and
tighten the bolts finger tight.
15 Engine block- cleaning
2
Caution: The core plugs (also known as
freeze or soft plugs) may be difficult or
impossible to retrieve if they’re driven
completely into the engine block coolant
passages.
1Using the blunt end of a punch, tap in on
the outer edge of the core plug to turn the
plug sideways in the bore. Then using pliers,
pull the core plug from the engine block (see
illustrations).
2B•10 Engine removal and overhaul procedures
14.5 The right side of each main bearing
cap is stamped with a number (left arrow)
that corresponds to the stamped number
on the pan rail (right arrow)15.1a A hammer and a large punch can be
used to knock the core plugs sideways in
their bores15.1b Pull the core plugs from the engine
block with pliers
3261 Jaguar XJ6 14.1 Checking crankshaft endplay with a dial indicator
14.3 Checking crankshaft endplay with a feeler gauge

is the difference between the parallel and
perpendicular readings. Compare your results
to this Chapter’s Specifications.
8If the cylinder walls are badly scuffed or
scored, or if they’re out-of-round or tapered
beyond the limits given in this Chapter’s
Specifications, have the engine block rebored
and honed at an automotive machine
workshop. If a rebore is done, oversize
pistons and rings will be required.
9Using a precision straightedge and feeler
gauge, check the engine block deck (the
surface that mates with the cylinder head) for
distortion (see illustration 10.13). If it’s
distorted beyond the specified limit, it can be
resurfaced by an automotive machine
workshop.
10If the cylinders are in reasonably good
condition and not worn to the outside of the
limits, and if the piston-to-cylinder clearances
can be maintained properly, then they don’t
have to be rebored. Honing is all that’s
necessary (refer to Section 17).
17 Cylinder honing
3
1Prior to engine reassembly, the cylinder
bores must be honed so the new piston rings
will seat correctly and provide the best
possible combustion chamber seal. Note:If
you don’t have the tools or don’t want to
tackle the honing operation, most automotive
machine shops will do it for a reasonable fee.
2Before honing the cylinders, refit the main
bearing caps (without bearing inserts) and
tighten the bolts to the specified torque.
3Two types of cylinder hones are commonly
available - the flex hone or “bottle brush” type
and the more traditional surfacing hone with
spring-loaded stones. Both will do the job, but
for the less-experienced mechanic the “bottle
brush” hone will probably be easier to use.
You’ll also need some paraffin or honing oil,
rags and a variable-speed electric drill motor.
The drill motor should be operated at a
steady, slow speed. Proceed as follows:
a) Mount the hone in the drill motor,
compress the stones and slip it into the
first cylinder (see illustration).
Warning: Be sure to wear safety
goggles or a face shield!
b) Lubricate the cylinder with plenty of
honing oil, turn on the drill and move the
hone up-and-down in the cylinder at a
pace that will produce a fine crosshatch
pattern on the cylinder walls. Ideally, the
crosshatch lines should intersect at
approximately a 60° angle (see
illustration). Be sure to use plenty of
lubricant and don’t take off any more
material than is absolutely necessary to
produce the desired finish. Note:Piston
ring manufacturers may specify a smallercrosshatch angle than the traditional 60° -
read and follow any instructions included
with the new rings.
c) Don’t withdraw the hone from the cylinder
while it’s running. Instead, shut off the drill
and continue moving the hone up-and-
down in the cylinder until it comes to a
complete stop, then compress the stones
and withdraw the hone. If you’re using a
“bottle brush” type hone, stop the drill
motor, then turn the chuck in the normal
direction of rotation while withdrawing the
hone from the cylinder.
d) Wipe the oil out of the cylinder and repeat
the procedure for the remaining cylinders.
4After the honing job is complete, chamfer
the top edges of the cylinder bores with a
small file so the rings won’t catch when the
pistons are installed. Be very careful not to
nick the cylinder walls with the end of the file.
5The entire engine block must be washed
again very thoroughly with warm, soapy water
to remove all traces of the abrasive grit
produced during the honing operation. Note:
The bores can be considered clean when a
lint-free white cloth - dampened with clean
engine oil - used to wipe them out doesn’t
pick up any more honing residue, which will
show up as grey areas on the cloth. Be sure to
run a brush through all oil holes and galleries
and flush them with running water.
6After rinsing, dry the engine block and
apply a coat of light rust preventive oil to all
machined surfaces. Wrap the engine block in
a plastic bag to keep it clean and set it aside
until reassembly.
18 Pistons/connecting rods-
inspection
2
1Before the inspection process can be
carried out, the piston/connecting rod
assemblies must be cleaned and the original
piston rings removed from the pistons. Note:
Always use new piston rings when the engine
is reassembled.
2Using a piston ring refitting tool, carefully
remove the rings from the pistons. Be careful
not to nick or gouge the pistons in the
process.
3Scrape all traces of carbon from the top of
the piston. A hand-held wire brush or a piece
of fine emery cloth can be used once the
majority of the deposits have been scraped
away. Do not, under any circumstances, use a
wire brush mounted in a drill motor to remove
deposits from the pistons. The piston material
is soft and may be eroded away by the wire
brush.
4Use a piston ring groove-cleaning tool to
remove carbon deposits from the ring
grooves. If a tool isn’t available, a piece
broken off the old ring will do the job. Be very
careful to remove only the carbon deposits -
don’t remove any metal and do not nick or
scratch the sides of the ring grooves (see
illustrations).
5Once the deposits have been removed,
clean the piston/connecting rod assemblies
with solvent and dry them with compressed
air (if available). Make sure the oil return holes
2B•12 Engine removal and overhaul procedures
17.3a A “bottle brush” hone will produce
better results if you have never done
cylinder honing before17.3b The cylinder hone should leave a
smooth, crosshatch pattern with the lines
intersecting at approximately a 60° angle
18.4a The piston ring grooves can be
cleaned with a special tool, as shown . . .18.4b . . . or a section of a broken ring
3261 Jaguar XJ6

in the back sides of the ring grooves and the
oil hole in the lower end of each rod are clear.
6If the pistons and cylinder walls aren’t
damaged or worn excessively, and if the
engine block is not rebored, new pistons
won’t be necessary. Normal piston wear
appears as even vertical wear on the piston
thrust surfaces and slight looseness of the top
ring in its groove. New piston rings, however,
should always be used when an engine is
rebuilt.
7Carefully inspect each piston for cracks
around the skirt, at the pin bosses and at the
ring lands.
Caution: Some early 1988 3.6 litre engines
(before engine no. 9D 121113) have
incorrectly-stamped pistons. On these, the
word FRONT is actually stamped on the rear
of the pistons. Correct pistons will have the
cast arrows on the inside of the skirt to your
left when facing the word FRONT.
8Look for scoring and scuffing on the thrust
faces of the skirt, holes in the piston crown
and burned areas at the edge of the crown. If
the skirt is scored or scuffed, the engine may
have been suffering from overheating and/or
abnormal combustion, which caused
excessively high operating temperatures. The
cooling and lubrication systems should be
checked thoroughly. A hole in the piston
crown is an indication that abnormal
combustion (pre-ignition) was occurring.
Burned areas at the edge of the piston crown
are usually evidence of spark knock
(detonation). If any of the above problems
exist, the causes must be corrected or the
damage will occur again. The causes may
include intake air leaks, incorrect air/fuel
mixture, incorrect ignition timing and EGR
system malfunctions.
9Corrosion of the piston, in the form of small
pits, indicates that coolant is leaking into the
combustion chamber and/or the crankcase.
Again, the cause must be corrected or the
problem may persist in the rebuilt engine.
10Measure the piston ring groove clearance
by laying a new piston ring in each ring groove
and slipping a feeler gauge in beside it (see
illustration). Check the clearance at three or
four locations around each groove. Be sure touse the correct ring for each groove - they are
different. If the clearance is greater than that
listed in this Chapter’s Specifications, new
pistons will have to be used.
11Check the piston-to-bore clearance by
measuring the bore (see Section 16) and the
piston diameter. Make sure the pistons and
bores are correctly matched. Measure the
piston across the skirt, at a 90° angle to
the piston pin (see illustration). Subtract the
piston diameter from the bore diameter to
obtain the clearance. If it’s greater than
specified, the engine block will have to be
rebored and new pistons and rings installed.
12Check the piston-to-rod clearance by
twisting the piston and rod in opposite
directions. Any noticeable play indicates
excessive wear, which must be corrected.
13If the pistons must be removed from the
connecting rods for any reason, the rods
should be taken to an automotive machine
workshop, to be checked for bend and twist,
since automotive machine shops have special
equipment for this purpose.
14Check the connecting rods for cracks and
other damage. Temporarily remove the rod
caps, lift out the old bearing inserts, wipe the
connecting rod and cap bearing surfaces
clean and inspect them for nicks, gouges and
scratches. After checking the connecting
rods, renew the old bearings, slip the caps
into place and tighten the nuts finger tight.
Note:If the engine is being rebuilt because of
a connecting rod knock, be sure to refit new
rods.
19 Crankshaft- inspection
3
1Clean the crankshaft with solvent and dry it
with compressed air (if available). Be sure to
clean the oil holes with a stiff brush and flush
them with solvent.
2Check the main and connecting rod bearing
journals for uneven wear, scoring, pits and
cracks.
3Remove all burrs from the crankshaft oil
holes with a stone, file or scraper.4Check the remainder of the crankshaft for
cracks and other damage. It should be
magnafluxed to reveal hidden cracks - an
automotive machine workshop will handle the
procedure.
5Using a micrometer, measure the diameter
of the main and connecting rod journals and
compare the results to this Chapter’s
Specifications (see illustration). By
measuring the diameter at a number of points
around each journal’s circumference, you’ll be
able to determine whether or not the journal is
out-of-round. Take the measurement at each
end of the journal, near the crank throws, to
determine if the journal is tapered. Crankshaft
runout should be checked also, but large V-
blocks and a dial indicator are needed to do it
correctly. If you don’t have the equipment,
have a machine workshop check the runout.
6If the crankshaft journals are damaged,
tapered, out-of-round or worn beyond the
limits given in the Specifications, have the
crankshaft reground by an automotive
machine workshop. Be sure to use the correct
size bearing inserts if the crankshaft is
reconditioned.
7Check the oil seal journals at each end of
the crankshaft for wear and damage. If the
seal has worn a groove in the journal, or if it’s
nicked or scratched, the new seal may leak
when the engine is reassembled. In some
cases, an automotive machine workshop may
be able to repair the journal by pressing on a
thin sleeve. If repair isn’t feasible, a new or
different crankshaft should be installed.
8Refer to Section 20 and examine the main
and big-end bearing inserts.
20 Main and big-end bearings-
inspection and selection
3
Inspection
1Even though the main and big-end bearings
should be replaced with new ones during the
engine overhaul, the old bearings should be
retained for close examination, as they may
Engine removal and overhaul procedures 2B•13
2B
19.5 Measure the diameter of each
crankshaft journal at several points to
detect taper and out-of-round conditions
3261 Jaguar XJ6 18.10 Check the ring groove clearance
with a feeler gauge at several points
around the groove
18.11 Measure the piston diameter at a
90° angle to the piston pin, at the bottom
of the piston pin area - a precision caliper
may be used if a micrometer isn’t available