2001 NISSAN PICK-UP Repair Manual

2. Reinstall all removed parts in the reverse order of removal.
+Confirm that no foreign objects are adhering to the installa-
tion planes of the oil cooler or block.
+Tighten the connecting bolt after aligning the stopper on the
cylinder block side with protrusion of the oil cooler.
SLC477B
ENGINE LUBRICATION SYSTEMYD25DDTi
Oil Cooler (Cont'd)
LC-3007

Overheating Cause Analysis
TROUBLESHOOTING CHART
Symptom Check items
Cooling system parts
malfunctionPoor heat transferWater pump malfunction Worn or loose drive belt
Ð Thermostat stuck closed Ð
Damaged finsDust contamination or
paper clogging
Mechanical damage
Clogged radiator cooling
tubeExcess foreign material
(rust, dirt, sand, etc.)
Reduced air flowCooling fan does not
operate
ÐÐ High resistance to fan
rotation
Damaged fan blades
Damaged radiator
shroudÐÐÐ
Improper coolant mixture
ratioÐÐÐ
Poor coolant quality Ð Ð Ð
Insufficient coolantCoolant leaksCooling hoseLoose clamp
Cracked hose
Water pump Poor sealing
Radiator capLoose
Poor sealing
RadiatorO-ring for damage, dete-
rioration or improper fit-
ting
Cracked radiator tank
Cracked radiator core
Reservoir tank Cracked reservoir tank
Overflowing reservoir
tankExhaust gas leaks into
cooling systemCylinder head deteriora-
tion
Cylinder head gasket
deterioration
ENGINE COOLING SYSTEMYD25DDTi
LC-3008

Symptom Check items
Except cooling system
parts malfunctionÐ Overload on engineAbusive drivingHigh engine rpm under
no load
Driving in low gear for
extended time
Driving at extremely high
speed
Power train system mal-
function
Ð Installed improper size
wheels and tires
Dragging brakes
Improper ignition timing
Blocked or restricted air
flowBlocked bumper Ð
Ð Blocked radiator grilleInstalled car brassiere
Mud contamination or
paper clogging
Blocked radiator Ð
Blocked condenser
Ð
Installed large fog lamp
ENGINE COOLING SYSTEMYD25DDTi
Overheating Cause Analysis (Cont'd)
LC-3009

Cooling Circuit
SLC478B
ENGINE COOLING SYSTEMYD25DDTi
LC-3010

System Check
WARNING:
Never remove the radiator cap when the engine is hot; seri-
ous burns could be caused by high pressure fluid escaping
from the radiator.
Wrap a thick cloth around the cap and carefully remove it by
turning it a quarter turn to allow built-up pressure to escape
and then turn the cap all the way off.
CHECKING RADIATOR CAP
To check radiator cap, apply pressure to cap with a tester.
Radiator cap relief pressure:
Standard
78-98kPa
(0.78 - 0.98 bar, 0.8 - 1.0 kg/cm
2, 11 - 14 psi)
Limit
59 kPa (0.59 bar, 0.6 kg/cm
2, 9 psi)
Pull the negative pressure valve to open it.
Check that it closes completely when released.
+Check the radiator cap negative pressure valve for contami-
nation or damage to the valve seat.
+Move the negative pressure valve to check for abnormalities
to the opening/shutting operation.
CAUTION:
+Be sure to perform the inspections after cooling down
the engine.
+Before connecting the radiator cap to the tester, apply
water or LLC to the cap sealing.
+Replace the radiator cap if abnormalities are found with the
negative pressure valve, or if the valve opening pressure is
out of the standard range.
CHECKING COOLING SYSTEM FOR LEAKS
To check for leakage, apply pressure to the cooling system with
a tester.
Testing pressure:
157 kPa (1.57 bar, 1.6 kg/cm
2, 23 psi)
CAUTION:
+Higher than the specified pressure may cause radiator
damage.
+Be sure to perform the inspections after cooling down
the engine.
+Use a hose adapter between the cap tester and filler
SLC755AC
SMA967B
SLC756AA
ENGINE COOLING SYSTEMYD25DDTi
LC-3011

neck to prevent the radiator filler neck from deforming.
+If any abnormalities are found, repair or replace the malfunc-
tioning parts.
Water Pump
REMOVAL AND INSTALLATION
CAUTION:
+When removing water pump assembly, be careful not to
get coolant on drive belt.
+Water pump cannot be disassembled and should be
replaced as a unit.
+After installing water pump, connect hose and clamp
securely, then check for leaks using radiator cap tester.
1. Gasket
2. Water pump3. Water pump pulley 4. Coupling
REMOVAL
1. Drain engine coolant. Refer to ªChanging Engine Coolantº in
MA section.
2. Remove radiator shroud.
3. Remove cooling fan and coupling.
4. Remove drive belts. Refer to ªDrive Beltsº in EM section.
5. Remove the water pump pulley.
6. Remove the water pump.
INSPECTION
+Check for rust and contamination adhering to the water pump
and vane.
+Turn the pump shaft by hand, and check that the pump turns
smoothly without looseness.
CAUTION:
Do not disassemble cooling fan coupling.
INSTALLATION
+Install the parts in the reverse order of removal.
SLC479B
ENGINE COOLING SYSTEMYD25DDTi
System Check (Cont'd)
LC-3012

+Install the water pump pulley with the front mark (painted
white, used to prevent errors during assembly) facing the
front of the engine. Refer to the figure on the previous page.
ENGINE COOLING SYSTEMYD25DDTi
Water Pump (Cont'd)
LC-3013

Thermostat and Water Piping
REMOVAL AND INSTALLATION
+Be careful not to spill coolant over engine compartment.
Use a rag to absorb coolant.
1. Drain engine coolant. Refer to ªChanging Engine Coolantº in
MA section.
2. Remove water inlet.
3. Remove thermostat.
4. Install thermostat with jiggle valve facing upward.
+Carefully install the rubber ring to the flange of the
thermostat, making sure it does not slip out of place.
5. After installation and refilling coolant, run engine for a few
minutes, and check for leaks.
SLC480B
JLC300B
ENGINE COOLING SYSTEMYD25DDTi
LC-3014