1987 NISSAN PULSAR engine

70 Cooling and Heating Systems


Installed view of the heater hoses. 1.6 liter models with the air cleaner removed for clarity
.
When the engine is at normal operating
temperature and the heater valve is open,
both of the heater hoses should feel
warm/hot. If the valve is not allowing the
coolant to flow, one hose will be hot while
the other will be cold.

NO COOLED AIR INSIDE VEHICLE
(1) Compressor drive belt slipping or broken:
Renew and/or adjust the drive belt as described in the
Engine Tune-up section.
(2) Insufficient refrigerant: Check the system for
leaks and charge as necessary. Refer to the Air
Conditioning heading in th is section for information
on checking the refrigerant level. (3) Compressor inoperative: Check for power to
the compressor clutch before removing the compres-
sor for repair by a specialist. (4) Heater system allowing warm air to mix with
cooled air: Check the operation of the heater system.
NOTE: The above trouble shooting proce-
dures are basic checks only. If the air
conditioning system is suspect, it is rec-
ommended that the vehicle be taken to an
authorized dealer for testing and repair.
It is normal for water to be seen drain-
ing under the vehicle from the evaporator
after the vehicle has been operated with
the air conditioning on.

3. DESCRIPTION
The cooling system is of the sealed, pressurized
type with fan and water pump assistance. The system
is pressurized in order to raise the boiling point of the
coolant and so increase the efficiency of the engine.

Provision for pressure a nd vacuum relief of the
system is incorporated in the radiator cap.

The radiator overflow hose is connected to a
reserve tank mounted adjacent to the battery. As the
coolant volume expands due to an increase in tem-
perature, the pressure valve in the radiator cap opens
and allows the excess coolant to flow into the reserve
tank. When the engine is stopped and the temperature
of the coolant falls, the vacuum valve in the radiator
cap opens and allows the excess coolant in the reserve
tank to siphon back into the radiator. Thus the
necessity for frequent topping up of the coolant is
eliminated.

The temperature of the cooling system is con-
trolled by a thermostat located in the thermostat
housing attached to the cylinder head.

The thermostat prevents circulation of coolant
through the radiator by directing coolant through the
by-pass circuit, until the engine has reached operating
temperature. This restricted circulation allows the
engine to reach operating temperature quickly, im-
proving drivability and fuel economy.

Removal of the thermostat to cure overheating is
not recommended because th e by-pass circuit will
remain open reducing the amount of water flowing
through the radiator.

An anti-corrosion inhibitor should always be
added to the coolant to protect the cooling and
heating systems from corrosion.

The water pump is mounted to the front of the
engine and is driven by the camshaft drive belt. It is
equipped with a double row ball bearing and a spring
loaded seal assembly. The water pump is a disposable
unit and cannot be repaired.

The fan is driven by an electric motor which is
actuated by the coolant temperature sensor and the
control unit.

On vehicles equipped with air conditioning, an
additional electric fan is m ounted to the radiator. This
fan is controlled by a sw itch connected to the air
conditioning compressor.

The radiator consists of an aluminum core with
plastic side tanks. Minor damage to the core can be
repaired using Nissan repair agent.

The left hand tank of the radiator houses the
transaxle oil cooler on automatic transaxle models.

To drain the cooling system a drain plug is
provided on the lower radiator pipe outlet.

4. RADIATOR
NOTE: To avoid scalding, use caution when
releasing the radiator cap on an engine
which is at the normal operating tempera-
ture. Turn the cap anti-clockwise to the first
stop and allow any pressure in the system to
release. When the pressure is released turn
the cap past the stop and remove it from the
radiator.

Cooling and Heating Systems 71

TO DRAIN AND REFILL
(1) Place a drain tin under the radiator drain
plug.
(2) Switch the heater controls to the maximum
heat position. (3) Remove the radiator cap and open the
radiator drain plug.
(4) Disconnect the reserve tank hose from the
radiator filler neck. (5) Lower the end of the hose and drain the
coolant from the reserve tank. (6) After all the coolant has drained from the
cooling system, install the radiator drain plug
ensuring
that the plug seal is in good condition. (7) Disconnect the wire from the temperature
sender switch and remove the switch using a suitable
spanner.
(8) Using a clean container, mix Nissan long life
coolant with clean soft water to the proportions
stipulated on the coolant container.
(9) Slowly pour the premixed coolant into the
radiator until the radiator is full and all air has
escaped through the temperat ure sender switch hole.
Install the radiator cap. (10) Fill the coolant reserve tank to the Maxi-
mum mark.
(11) Start the engine and allow it to idle.
(12) When coolant starts to flow through the
temperature sender switch hole, install the temperature
sender switch and tighten securely. (13) Continue idling the engine until the cooling
fan is activated.
(14) Switch the engine off and allow it to cool.
(15) Refill the radiator using coolant and install
the radiator cap.

Dismantled view of the radiator and associated components. Automatic transaxle model with
air conditioning.

72 Cooling and Heating Systems

(16) After the vehicle has been driven several
kilometers check the coolant level in the reserve tank
and top up if necessary.

TO REMOVE
(1) Drain the cooling system as previously de-
scribed.
(2) Loosen the hose clamps and disconnect the
hoses from the radiator. (3) If applicable disconnect the automatic trans-
axle oil cooler hoses from the left hand side radiator
tank. Plug the hoses and fitt ings to prevent the entry
of dirt and the loss of fluid.
(4) Disconnect the hose from the reserve tank at
the top of the radiator. (5) On models with air conditioning, remove the
hoses and support bracket bolts and move the bracket
and hoses away from the top of the radiator. (6) Remove the radiator support bracket bolts
from the radiator support pa nel and lift the radiator
from the lower mountings and out of the vehicle.
NOTE: A radiator that has been in use for
some time should not be allowed to stand
empty for any length of time. The radiator
should be immersed in a tank of coolant or
otherwise kept full. If applicable, ensure that
no coolant is allowed to enter the automatic
transaxle oil cooler in the left hand side tank
of the radiator.

Failure to observe this precaution may
result in overheating when the engine is put
back into service. This is caused by internal
deposits in the radiator drying and flaking
and so obstructing the circulation of the
coolant in the system.

TO FLUSH AND CLEAN
(1) Remove the radiator as previously described.
(2) Apply a water hose to the radiator outlet and
reverse flush the radiator until the water flowing from
it is clean.

Cleaning the radiator core from the rear to the front
using a garden hose.
(3) Stand the radiator upright and apply a
stream of water or compressed air to the radiator core
from the rear to [he front. Maintain this procedure
until all dirt and foreign matter is removed from the
radiator core.
(4) With the aid of a light, make a visual check
of the core tubes through the radiator inlet or outlet
fittings. If it is apparent that the tubes are severely
impregnated with flakes of rust it will be necessary to
renew the radiator assembly.
TO REPAIR

The repair procedure described below is only
suitable for holes occurring in the radiator core tubes
that are not bigger than approximately 1 mm.

(1) Suitably mark the area of the leak using a
piece of chalk or similar. (2) Remove the radiator from the vehicle as
previously described, clean it thoroughly and dry the
damaged area with a hair dryer. (3) If necessary, carefully cut away or bend the
fins from the tubes to expose the affected area.
NOTE: Do not remove more than 25 mm
total finning from the radiator or cooling
performance will be affected.

(4) Clean the damaged area carefully using a
scraper and wipe clean using a cloth moistened with
petrol.
(5) Apply well mixed Nissan or Holden adhe-
sive part number 21411-J7025, or equivalent, spar-
ingly to the damaged area using a wooden spatula.
(6) Allow the repair to dry in ambient condi-
tions for a minimum of 3 hours before installing the
radiator to the vehicle and testing for leaks. Do not
use heat to promote drying.
TO INSTAL

Installation is a reversal of the removal procedure
with attention to the following points:
Reverse flushing the radiator using water pressure.

Cooling and Heating Systems 73
(1) Renew all hoses that show signs of cracking
or perishing.
(2) Before finally tightening the hose clips, en-
sure that the hoses are push ed fully onto the radiator
and are not kinked. (3) On automatic transaxle models, ensure that
the oil cooler hoses are correctly installed to the
radiator and show no signs of leakage. Check and top
up the automatic transaxle fluid as necessary.
5. COOLING FAN
The radiator cooling fan is controlled by the
electronic control unit, and on vehicles with air
conditioning, the condenser fan relay. On vehicles
with air conditioning there are two cooling fans, one
is larger than the other. The large fan is for the
radiator and the smaller fan provides extra cooling
when the air conditioning is activated. Each fan is
controlled by a separate system.

TO TEST COOLING FAN AND SYSTEM
(1) With the cooling system cold and the air
conditioning, if applicable, switched off, switch the
ignition On and confirm that the cooling fan is
stationary.

NOTE: Leave the ignition On for all tests
unless otherwise stated.

(2) In the above test, if the cooling fan rotates,
proceed as follows:

(a) Disconnect the cooling fan relay from the
rear of the engine compartment relay box.
(b) If the fan stops, backprobe terminal C1 at
the electronic control unit using an LED test lamp
connected to the positive battery terminal. If no
circuit exists, renew the cooling fan relay.

View showing the location of the diagnostic link
connector. Passengers seat removed for clarity.
If a circuit exists, check the wiring harness
between the electronic control unit and the relay for
short circuits to earth and repair if necessary. If no
short circuit is present renew the electronic control
unit.


Schematic layout of the cooling fan, coolant temper-
ature sensor and related electrical components.

Installed view of the engine compartment relays. KEY

1. To Battery
2. Fusible link
COLOUR CODE
3. Fusible link
B-Black
4. Fusible linkL- Blue
5. I
gnition relayY- Yellow
6. Fuse 20 am
pW-White
7. Coolin
g fan relayO-Orange
8. Coolin
g fan
9. Coolant tem
perature
sensor
10. To air conditionin
g
fan rela
y
11. To throttle
position
sensor
12. Control unit

74 Cooling and Heating Systems
NOTE: Refer to the Fuel and Engine Man-
agement section for the correct procedure for
backprobing the control unit.

(3) In operation (1) if the cooling fan is station-
ary proceed as follows:

(a) Connect a jumper lead between the terminals
A and B of the diagnostic link connector. (b) if the fan runs, the fan circuit is satisfactory.
If the engine is overheating check the coolant temper-
ature sensor as described in the Fuel and Engine
Management section under the appropriate codes. (c) If the fan does not run, check the fuse (6) and
the fusible link (4) show n on the illustration.
(d) Backprobe terminal C1 at the electronic
control unit using an LED t est lamp connected to the
positive battery terminal. If no circuit exists, renew
the electronic control unit. (e) If the fuse and fusible links are serviceable,
ensure that power is available at the white and pink
wires from the fuse and fusible link of the cooling fan
relay. Repair any faults in the wiring to that point if
necessary. (f) Switch the ignition Off. disconnect the
cooling fan wiring connector at the radiator and
connect power to the fan. Renew the fan if it does not
run.

(4) On air conditioned models, remove the
jumper lead from the ALDL connector if still in-
stalled, start the engine and allow it to idle. Switch the
air conditioning on and ensu re that the cooling fan
runs.

If the cooling fan is opera ting as described above
but cooling system problems still exist, refer to the
Trouble Shooting heading at the start of this section.

TO REMOVE AND INSTAL COOLING FAN
(1) Disconnect the negative battery terminal.
(2) Disconnect the cooling fa n and, if applicable,
the air conditioning fan wiring connectors at the
upper edge of the radiator. (3) On models with air conditioning, remove the
compressor hose bracket bolt from the centre of the
radiator support panel.

Dismantled view of the fans and the shroud assembly. Air conditioned model.

Cooling and Heating Systems 75
(4) Remove the bolts retaining the fan shroud
assembly to the radiator and carefully move the
shroud assembly upwards and towards the engine to
release it from the lower mountings.

NOTE: On models with air conditioning, it
will be necessary to hold the air conditioning
compressor hoses toward s the engine to
allow clearance for removal of the shroud
assembly.

(5) If necessary, remove the fan from the fan
motor by removing the retaining bolts or on some
models the nut and washers.
(6) If necessary, remove the fan motor from the
shroud assembly by removing the retaining bolts or
nuts. Installation is a reversal of the removal procedure
with attention to the following points:

(1) Ensure all the fan motor and fan retaining
nuts and bolts are tightened securely. (2) Ensure that all the rubber mountings are in
good condition. Installation is a reversal of the removal procedure
with attention to the following points:

(1) Ensure that all sealing surfaces are clean.
(2) Renew the O ring on installation.
(3) Tighten the thermostat cover retaining bolts
securely.
(4) Fill the cooling system as previously de-
scribed ensuring that the heater control lever is in the
maximum heat position. Check for coolant leaks.
TO CHECK

NOTE: A visual examination of the thermo-
stat will often determine its serviceability
and make further testing unnecessary. For
instance, a thermostat with its valve fully-
open when removed from a cold engine is
obviously faulty and should be renewed.

Remove the thermostat from the thermostat
6. THERMOSTAT
Special Equipment Required:
To Check — Thermometer

TO REMOVE AND INSTAL
(1) Drain the cooling system as previously de-
scribed under the Radiator heading.
(2) On 1.6 liter models, remove the air cleaner
assembly. Refer to the Fuel and Engine Management
section if necessary. (3) Disconnect the top radiator hose from the
thermostat cover.
(4) Remove the bolts retaining the thermostat
cover to the thermostat housing. (5) Remove the thermostat cover, thermostat
and O ring from the thermostat housing.
NOTE: The thermostat and cover are ser-
viced as a unit and cannot be renewed
separately.


View of the thermostat removed from the vehicle and dismantled for testing. Line drawing showing the correct method to test the
thermostat.

(4) Progressively heat the mixture noting the
temperature reading on the thermometer as the ther-
mostat valve commences to open and when it is fully
open.

See the Specifications for opening and fully open
temperatures.

A thermostat which is not opening or is not open
at the specified temperatures should be renewed.

Cooling and Heating Systems
7. THERMOSTAT HOUSING
Special Equipment Required:
To Adjust Camshaft Drive Belt — Adjusting tool
TO REMOVE AND INSTAL
(1) Disconnect the negative battery terminal.
(2) On 1.6 liter models, remove the air cleaner
assembly from the engine. Refer to the Fuel and
Engine Management section if necessary. (3) Drain the cooling system as previously de-
scribed. (4) Remove the camshaft drive belt as described
in the Engine section under the heading Camshaft
Drive Belt. (5) Remove the bolts retaining the camshaft
drive belt rear cover to the cylinder block and remove
the rear cover.
\ COOLANT TEMPERATURE SENSOR TEMPERATURE SENDER SWITCH
View of the thermostat housing and
components.
(6) Disconnect the top radi ator hose, the heater
hose and the inlet manifold heater hose from the
thermostat housing.
(7) Disconnect the wire from the temperature
sender switch and the coolant temperature sensor. (8) Remove the bolts retaining the thermostat
housing to the cylinder head and remove the thermo-
stat housing and the O ring from the cylinder head. Installation is a reversal of the removal procedure
with attention to the following points:

(1) Ensure that all mounting faces are clean.
(2) Renew the O ring on installation.
NOTE; Ensure that the O ring is not
twisted. Do not use sealant.

(3) Tighten the thermostat housing retaining
bolts to the specified torque. (4) Adjust the camshaft drive belt tension as
described in the Engine section under the heading
Camshaft Drive Belt. (5) Fill the cooling system as previously de-
scribed and check for coolant leaks. 8. WATER PUMP

Special Equipment Required:
To Adjust Camshaft Drive Belt — Adjusting tool
TO REMOVE AND INSTAL
NOTE: The water pump is non-repairable
and if faulty must be renewed as a complete
assembly.

(1)
Drain the cooling system as previously de-
scribed.
(2) Remove the camshaft drive belt as described
in the Engine section under the heading Camshaft
Drive Belt. (3) Remove the water pump retaining bolts and
remove the water pump and the O ring from the
engine. Installation is a reversal of the removal procedure
with attention to the following points:


View of the water pump and components removed
from the vehicle.
(1) Ensure that all mounting faces are clean.
(2) Use a new O ring and smear it with a liberal
amount of silicone grease.
(3) Install the water pump to the engine but
do
not tighten the retaining bolts until the camshaft drive
belt has been installed and tensioned correctly as
described in the Engine section under the heading
Camshaft Drive Belt.
(4) Fill the cooling system as previously de-
scribed in this section and check for coolant leaks.
9. WELCH PLUGS

To facilitate the casting of the cylinder block and
cylinder head passages and water jackets, a number of
openings had to be ma de at manufacture.

Cooling and Heating Systems 77
These openings are plugged with welch plugs. The
plugs may have to be renewed when cleaning the
engine water jackets or when defective due to corro-
sion.

TO RENEW
NOTE: If a welch plug is found to be
corroded it is good policy to renew all the
welch plugs.

(1) Drain the radiator and cylinder block.
(2) Remove the necessary engine components or
accessories to gain ampl e working space around the
welch plug. (3) Using a punch and hammer, tap the welch
plug on its outer circumference into its opening. (4) Grasp the edge of the welch plug with a pair
of multi-grip pliers and using the shoulder of the pliers
as a fulcrum, lever the plug out of its opening. (5) Thoroughly clean and dry the welch plug
opening.
(6) Lightly smear the edge of a new welch plug
and the opening with Loctite 675. (7) Place the welch plug onto the opening and
using a tube or socket fitting the rim of the plug, drive
the plug squarely into its opening.
NOTE; The welch plug must be driven into
the opening straight and squarely or leaks
may occur.

(8) Install the components which were removed
to gain access to the plug. (9) Fill the cooling system as previously de-
scribed. With the reserve tank pressure cap installed,
run the engine until it reaches normal operating
temperature and check for coolant leaks.
10. HEATER UNIT, WATER VALVE AND
CONTROLS
DESCRIPTION
The heater controls use four adjustments to direct
air through the vehicle.

The air intake control selects fresh air from
outside the vehicle or recirculates air from inside the
vehicle. The recirculate position is used in dusty
conditions or to rapidly heat or cool the vehicle
interior. The fresh air positi on is the best to deodorize
the vehicle interior or demist the windscreen.

The air control lever is used to direct air to the
face outlets, the floor outle ts and the windscreen
outlets. This control also has two bi-level positions
where air may be directed to the face and floor outlets
or the windscreen and floor outlets.

The temperature control opens or shuts the heater
water valve to control the flow of engine coolant
through the heater core, which raises or lowers the
temperature of the air passing through the core.
Maximum heating is only available when the engine is
at the normal operating temperature.

The fan speed control switches the fan on and off
and is used to select the desired fan speed.

Air conditioned models use identical controls
with the addition of an air conditioner on/off button.
The centre of the button is illuminated when the air
conditioner is switched on.

Tap the welch plug on its ou ter circumference into the
cylinder block.
Using a correct fitting tube or socket, drive the welch
plug into its opening. View of the heater controls.