Diagnostic Procedure

Apply pressure to the cooling system with a tester, and check if the pressure drops.

Fig 1: Applying Pressure To Cooling System With A Tester

Courtesy of NISSAN MOTOR CO., U.S.A.

Testing pressure : 157 kPa (1.6 kg/cm ² , 23 psi)

OK or NG 

1. OK: GO TO 2.
2. NG: Check the following for leak.
   • Hose
   • Radiator
   • Water pump

     Refer to "WATER PUMP ".

Apply pressure to cap with a tester.

Radiator cap relief : 78 - 98 kPa 

pressure (0.8 - 1.0 kg/cm ² , 11 - 14 psi)

Fig 2: Applying Pressure To Cap With A Tester

Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG 

1. OK: GO TO 3.
2. NG: Replace radiator cap.

1. Check valve seating condition at normal room temperatures.

   It should seat tightly. 

2. Check valve opening temperature and valve lift.

   Valve opening temperature : 76.5°C (170°F) [standard] 

   Valve lift : More than 8 mm/90°C (0.31 in/194°F) 

3. Check if valve is closed at 5°C (9°F) below valve opening temperature.
Fig 3: Checking Valve Opening Temperature And Valve Lift
Courtesy of NISSAN MOTOR CO., U.S.A.

For details, refer to "THERMOSTAT ".

OK or NG 

1. OK: GO TO 4.
2. NG: Replace thermostat.

Check resistance as shown in the figure.

Fig 4: Checking Resistance

Courtesy of NISSAN MOTOR CO., U.S.A.

< Reference data >

Fig 5: Temperature Resistance Chart

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 6: Resistance Vs Temperature Graph

Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG 

1. OK: GO TO 5.
2. NG: Replace engine coolant temperature sensor.

If the cause cannot be isolated, go to , "MAIN 11 CAUSES OF OVERHEATING ".

1. INSPECTION END 

Perform FINAL CHECK by the following procedure after repair is completed. 

1. Warm up engine. Run the vehicle for at least 20 minutes. Pay attention to engine coolant temperature gauge on the instrument panel. If the reading shows an abnormally high temperature, another part may be malfunctioning.
2. Stop vehicle and let engine idle. Check the intake and exhaust systems for leaks by listening for noise or visually inspecting the components.
3. Allow engine to cool and visually check for oil and coolant leaks. Then, perform "Overall Function Check".