1993 FORD SIERRA gas type

Torque wrench settingsNmlbf ft
Radiator upper mounting nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 to 2515 to 18
Radiator lower mounting bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 to 126 to 9
Coolant pump bolts:
SOHC models:
M8 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 to 2113 to 15
M10 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 to 4226 to 31
CVH models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 to 116 to 8
CVH (R6A type) models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 to 105 to 7
DOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 to 2815 to 21
Thermostat housing bolts:
SOHC/DOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 to 2013 to 15
CVH models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 to 116 to 8
CVH (R6A type) models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 to 126 to 9
Cooling fan shroud-to-radiator nuts/bolts . . . . . . . . . . . . . . . . . . . . . . .8 to 116 to 8
Coolant pump pulley bolts:
SOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 to 2815 to 21
DOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 to 2515 to 18
Coolant pump/alternator drivebelt tensioner bolt:
CVH models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 to 3017 to 22
DOHC models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 to 9752 to 72
Cooling fan blades-to-fan hub bolts (SOHC models) . . . . . . . . . . . . . . .8 to 106 to 7
Air conditioning compressor-to-bracket bolts . . . . . . . . . . . . . . . . . . . .65 to 7548 to 55
Air conditioning compressor bracket-to-engine bolts:
M10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85 to 9263 to 68
M12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110 to 12081 to 89
Air conditioning condenser fan assembly-to-condenser bolts:
Models up to 1987 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 to 31 to 2
Models from 1987 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 to 116 to 8
Air conditioning condenser securing bolts (models from 1987) . . . . . . .27 to 3320 to 24
General information
The cooling system is of pressurised type,
and consists of a front mounted radiator,
coolant pump, cooling fan, wax type
thermostat, and an expansion tank.
The radiator matrix is manufactured from
honeycombed metal, and the end tanks are
made of plastic. On automatic transmission
models, the right-hand end tank incorporates
the transmission fluid cooler.
The coolant pump is located on the front
face of the engine block, and is belt-driven.
The pump is of the impeller type.
The cooling fan draws cold air over the
radiator matrix to assist the cooling process
when the forward speed of the vehicle is too
low to provide sufficient cooling airflow, or the
ambient temperature is unusually high. SOHC
models have a thermo-viscous fan, whereas
CVH and DOHC models have an
electrically-operated fan.
The thermo-viscous fan is controlled by the
temperature of the air behind the radiator.
When the air temperature reaches a
predetermined level, a bi-metallic coil
commences to open a valve within the unit,
and silicon fluid is fed through a system of
vanes. Half the vanes are driven directly by
the coolant pump, and the remaining half are
connected to the fan blades. The vanes are
arranged so that drive is transmitted to the fan
blades in relation to the viscosity of the silicon
fluid, and this in turn depends on ambienttemperature and engine speed. The fan is
therefore only operating when required, and
compared with direct-drive type fans
represents a considerable improvement in fuel
economy, drivebelt wear and fan noise.
The electrically-operated fan is switched on
by a temperature sensor mounted in the
thermostat housing when the temperature
reaches a predetermined level. The fan is
therefore only operating when required, and like
the thermo-viscous fan, offers a considerable
advantage over direct-drive type fans.
A thermostat is fitted. Its purpose is to
ensure rapid engine warm-up by restricting
the flow of coolant to the engine when cold
and also to assist in regulating the normal
operating temperature of the engine.
The expansion tank incorporates a pressure
cap which effectively pressurises the cooling
system as the coolant temperature rises,
thereby increasing the boiling point of the
coolant. The tank also has a further degas
function. Any accumulation of air bubbles in the
coolant is returned to the tank and released in
the air space, thus maintaining the efficiency of
the coolant. The pressure cap also incorporates
a vacuum relief valve which prevents a vacuum
forming in the system as it cools.
The system functions as follows. Cold
coolant in the bottom of the radiator circulates
through the bottom hose to the coolant pump
where the pump impeller pushes the coolant
through the passages within the cylinder
block, cylinder head and inlet manifold. After
cooling the cylinder bores, combustion
chambers and valve seats, the coolant
reaches the underside of the thermostat
which is initially closed. A small proportion ofthe coolant passes from the thermostat
housing to the expansion tank, but the main
circulation is through the inlet manifold,
automatic choke (where applicable), and
heater matrix, finally returning to the coolant
pump. When the coolant reaches a
predetermined temperature, the thermostat
opens and hot water passes through the top
hose to the top of the radiator. As the coolant
circulates through the radiator, it is cooled by
the flow of air to the vehicle’s forward motion,
supplemented by the action of the cooling fan
where necessary. By the time it reaches the
bottom of the radiator the coolant is cooled,
and the cycle is repeated. Circulation of
coolant continues through the expansion
tank, inlet manifold, automatic choke (where
applicable) and heater at all times, the heater
temperature being controlled by an air flap.
An air conditioning system is available as
an optional extra on certain models. In
conjunction with the heater, the system
enables any reasonable air temperature to be
achieved inside the vehicle; it also reduces
the humidity of the incoming air, aiding
demisting even when cooling is not required.
The refrigeration side of the air conditioning
system functions in a similar way to a
domestic refrigerator. A compressor, belt-
driven from the crankshaft pulley, draws
refrigerant in its gaseous phase from an
evaporator. The compressed refrigerant
passes through a condenser where it loses
heat and enters its liquid phase. After passing
through the dehydrator, which acts as a
reservoir and filter to extract moisture from
the circuit, the refrigerant returns to the
evaporator where it absorbs heat from the air
1General information and
precautions
3•2Cooling, heating and air conditioning systems