1999 JAGUAR S TYPE engine

V6 Engine AJ-V6/AJ28
32(LHD vehicles) or rear right (RHD) of the engine
bay and in the LHD location has a bleed valve on
the return pipe running across the bulkhead. The
pipe layout is shown in the ÔS-TYPE IntroductionÕ
Technical Guide. A dip tube within the bottle
ensures that coolant is drawn back into the engine
when it cools down.
A subsidiary circuit provides a series coolant feed
through the lower throttle body and top of the
intake manifold inlet. This is necessary to prevent
ice forming at low ambient temperatures at the
base of the throttle body and also in the positive
crankcase ventilation (PCV) port.
Hoses and Connectors
Coolant ducting consists of flexible hoses,
aluminium tubing and plastic tubing with
injection moulded rubber to plastic joints. All
coolant hose clamps are of the spring band type
and are glued to the hose with a pull off clip for
D.303.1374
HOSE LAYOUT
Electronic throttle
D.303.1374
fitting. The thermostat is enclosed in an
aluminium casting which is a separate component
supported by hose connections.
Top Hose
Bottom Hose
Heater Control
Valve
Thermostat
Coolant Pump

V6 EngineAJ-V6/AJ28
33
J.303.1378
HOSE LAYOUT
D.303.1378
Electronic Throttle
Top Hose
Bottom HoseFrom Heater
Control Valve
To
Reservoir
Bottle
Engine Coolant Outlet
A cast aluminium outlet junction bolts to both
cylinder heads to provide a single return flow to
the radiator top hose assembly.
D.303.1353
ENGINE COOLANT OUTLET
D.303.1353
To Engine
From Engine
To Heater
Control
Valve
ThermostatCoolant Pump

V6 Engine AJ-V6/AJ28
34Coolant Pump
The coolant pump is fitted via three bolts to the
engine front cover. The pulley is mounted in-
board of the pump assembly, between the pump
and front cover, and has a smooth surface which
is driven from the outer, non ribbed side of the
drive belt.
Coolant returns from the radiator and cabin
heater system are connected via hoses to inlets on
the front of the pump assembly. The outlet from
the pump is connected to the engine block via a
hose and a tubular casting bolted to the top front
of the block between the cylinders.
Radiator and Cooling Fan Assembly
The engine radiator is one component of the
cooling pack assembly which also includes the
PAS and transmission heat exchangers and the
A/C condenser. The cooling pack assembly and
the PAS and A/C systems are described in the
ÔS-TYPE IntroductionÕ Technical Guide and
transmission cooling is described elsewhere in
this Guide.
The radiator consists of an aluminium core,
26mm in thickness, with crimped on plastic end
tanks. A single electrical cooling fan and a fan
D.303.1213
COOLANT PUMP
D.303.1213
D.303.1375
RADIATOR AND FAN SHROUD ASSEMBLY
D.303.1375
Fan Speed
Regulator Module

V6 EngineAJ-V6/AJ28
35
J.303.1384
ENGINE BLOCK HEATER
D.303.1384
J.303.1377
FAN SPEED REGULATOR MODULE COOLING DUCT speed regulator module are fixed to the glass
filled nylon fan shroud assembly which is
mounted on the rear of the radiator end tanks via
two lower slots and pegs, two upper screws and
two clips at the bottom of the radiator. The A/C
system receiver drier bottle is also mounted on
the fan shroud assembly - see the
ÔS-TYPE IntroductionÕ Technical Guide.
The 500W fan motor drives a glass filled nylon
impeller over a continuously variable speed range
from 300RPM to 2900RPM and is controlled by a
regulator module mounted at the lower LH side of
the fan shroud. Since the fan speed regulator
module provides power drive to the fan, it has a
finned heat sink outer casing and is enclosed
within a cooling duct. The ducting extends
forwards below the cooling pack to receive an
inflow of air.
The radiator drain is located on the RH end tank.
Coolant
A new type of anti-freeze fluid is used for the
coolant mixture. This product is a conventional
ethylene glycol based fluid but with new organic
corrosion inhibitors instead of the silicate, nitrite
and other additives which are normally used.
These new corrosion inhibitors do not form a
deposit on the inner surfaces of the coolant
system and therefore provide improved heat
transfer (more efficient cooling), better
component protection and an extended coolant
life due to the low rate of depletion of the
additives. The recommended coolant change is
every five years or 250,000km (150,000miles).
Engine Block Heater
For markets subject to very low temperatures, an
engine coolant heater, for connection to an
external mains electrical supply, is screwed into
the RH side of the cylinder block adjacent to the
knock sensor. Two heaters are available, a 400W
115V unit with a two pin connector and a 600W
230V unit with flying lead.
J.303.1377

V6 Engine AJ-V6/AJ28
36
Fail Safe Cooling System
A unique feature of the V6 engine is the use of a fail safe cooling strategy, controlled by the EMS, in the
event of coolant loss leading to rising engine temperatures. The principle of the strategy involves
switching off one or more fuel injectors to inhibit combustion and reduce heat, thus allowing the flow of
ambient intake air to further cool the selected cylinders. By cycling the selected cylinders, ie switching
different injectors off for a period and in a sequence determined by EMS parameters, overall engine
temperature can be controlled sufficiently to allow the vehicle to be driven, at reduced power, for a
short distance. Throughout the malfunction period, instrument panel messages and warnings advise the
driver of the current status of the cooling system as described below.
Driver Indication and EMS Action
The fail safe strategy moves though different stages depending on engine temperature:
¥ Temperatures below 122û C (250û F) are within the normal range. At high temperatures below this
level the temperature gauge pointer enters the red zone.
¥ If the temperature rises to between 122û C - 127û C (250û F to 260û F) no action is taken by the EMS
which affects engine running but the following indications appear:
Temperature gauge pointer in red zone
Message Centre HIGH ENGINE TEMPERATURE
Warning light TEMP
Priority light red
Audible indicator single chime sounded
¥ If the temperature rises to 127û C (260û F) or above, the fail safe strategy operates. At 127û C (260û F),
the EMS will cut out one cylinder (the selected cylinder is varied) and as the temperature continues
to rise, this will increase to a maximum of three cylinders cut (with cylinder cycling). The following
indications are given:
Temperature gauge pointer in red zone
Message Centre ENGINE POWER REDUCED
Warning light TEMP
Priority light red
Audible indicator three chimes sounded
¥ At 166û C (300û F) or above, the fail safe strategy continues as described but the following
indications are given:
Temperature gauge pointer in red zone
Message Centre PULL OFF ROAD SAFELY alternates with TURN OFF IGNITION
Warning light TEMP flashes
Priority light red
Audible indicator five chimes sounded
¥ EMS shuts the engine down.

V6 EngineAJ-V6/AJ28
37
Front End Accessories Drive
D.303.1349
Drive Belt
A single six ribbed belt is driven from the
crankshaft damper pulley to drive the coolant
pump, generator, PAS pump and A/C pump. The
drive belt run is guided via two idler pulleys and
an automatic belt tensioner.
PAS Pump
Generator
D.303.1349
ENGINE ACCESSORIES AND DRIVE BELT
Coolant Pump
A/C Compressor
Drive Belt
Tensioner
Crankshaft
Damper Pulley
Idler pulley
Idler pulley

V6 Engine AJ-V6/AJ28
38
J.303.1348
Generator
The 120AH generator is fitted with a special casing
to enable it to be bolted directly to the engine via
three fixing points.
On the manual transmission vehicles, sudden
deceleration may result in generator momentum
driving the belt against the engine which is
slowing down, with possible effects on the life of
the drive belt. The generator pulley fitted to the
manual transmission vehicle incorporates a clutch
mechanism which allows it to freewheel in the
reverse drive (anti-clockwise) direction. Note that
a special tool is required to remove the pulley.
To improve generator control on all
engine/transmission variants, the generator now
has a four pin connector to provide two new
sensing signals:
¥ pin S is directly connected to the battery to
provide voltage feedback to the regulator
¥ the regulator senses field current and
produces a PWM signal from pin FR to the
PCM to indicate the generator duty cycle.
D.303.1350
DRIVE BELT TENSIONER
GENERATOR
D.303-1350
Drive Belt Tensioner
The drive belt tensioner is a similar type to that
fitted to the V8 engines. An index on the
tensioned arm rotates with wear against three
markings on the tensioner spring cap which
indicate the minimum and maximum lengths for a
new belt and the point at which the belt must be
replaced.
Replace Belt
Belt Wear
Indicator
New Belt Maximum Length
New Belt Minimum Length
Manual
transmission
pulleyAutomatic
transmission
pulley
J.303.1348

V6 EngineAJ-V6/AJ28
39
D.303.1351D.303.1352
PAS PUMPA/C COMPRESSOR
D.303.1352
D.303.1369
Idler Pulleys
Two idler pulleys are used, one fixed by a single
bolt to the front cover and a second (see
illustration) fixed via a mounting bracket to the
upper RH side of the cylinder head and front
cover.
PAS Pump
The PAS pump is fixed by a single bolt to the LH
cylinder head and by two bolts to the front cover.
The pulley is constructed of lightweight phenolic
material.
Air Conditioning Compressor
The A/C compressor is mounted on the lower LH
side of the engine and is secured by two bolts to a
bracket fixed to the bedplate and by two lower
bolts directly to the oil sump.IDLER PULLEY
D.303.1351
D.303.1369