Nissan MR16DDT Engine Cooling System

Precautions

WARNING: Always observe the following items for preventing accidental activation.

• To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death in the event of a collision that would result in air bag inflation, all maintenance must be performed by an authorized NISSAN/INFINITI dealer.
• Improper maintenance, including incorrect removal and installation of the SRS, can lead to personal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air Bag Module, see "SRS AIR BAG".
• Never use electrical test equipment on any circuit related to the SRS unless instructed to in this Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or harness connectors.

Precautions When Using Power Tools (Air or Electric) and Hammers

WARNING: Always observe the following items for preventing accidental activation.

• When working near the Air Bag Diagnosis Sensor Unit or other Air Bag System sensors with the ignition ON or engine running, never use air or electric power tools or strike near the sensor(s) with a hammer. Heavy vibration could activate the sensor(s) and deploy the air bag(s), possibly causing serious injury.
• When using air or electric power tools or hammers, always switch the ignition OFF, disconnect the battery, and wait at least 3 minutes before performing any service.

Preparation

Commercial Service Tools

System Description

Engine Cooling System

The engine cooling system circulates coolant to maintain optimal engine operating temperature. It consists of the radiator, water pump, thermostat, cooling fan, hoses, and various sensors and control valves.

M/T Models Coolant Flow:

Coolant is pumped by the water pump through the engine block and cylinder head. It then flows to the thermostat, which regulates flow to the radiator. From the radiator, cooled coolant returns to the water pump. The system also includes flow to the turbocharger and heater core.

CVT Models Coolant Flow:

Similar to M/T models, but also includes a flow path to the CVT oil warmer.

Engine Cooling System Schematic

Schematics illustrate the coolant flow paths for both M/T and CVT models, showing the interconnections between the radiator, reservoir tank, thermostat, water pump, engine oil cooler, cylinder head, cylinder block, turbocharger, and heater.

M/T Models Schematic:

Diagram shows coolant flow through the radiator, thermostat, water pump, cylinder block, cylinder head, turbocharger, and heater. A table indicates thermostat and water control valve states (Closed/Open).

CVT Models Schematic:

Diagram shows coolant flow similar to M/T, with the addition of the CVT oil warmer. A table indicates thermostat and water control valve states (Closed/Open).

Symptom Diagnosis: Overheating Cause Analysis

Troubleshooting Chart

Periodic Maintenance

Engine Coolant

Inspection

Level

• Check that the reservoir tank engine coolant level is within the "MIN" to "MAX" range when the engine is cool.
• Adjust the engine coolant level if necessary.

CAUTION: Refill with Genuine NISSAN Long Life Antifreeze/Coolant (blue) or equivalent, mixed with distilled or demineralized water. Refer to MA-10, "Fluids and Lubricants".

Leakage

• To check for leakage, apply pressure to the cooling system using the radiator cap tester (A) and adapter (B).
• Testing pressure: Refer to CO-26, "Radiator".

WARNING: Never remove the radiator cap when the engine is hot. Serious burns may occur from escaping high-pressure engine coolant.

CAUTION: Higher test pressure than specified may cause radiator damage.

NOTE: If engine coolant decreases, replenish with engine coolant. If leaks are found, repair or replace damaged parts.

Draining

WARNING: Never remove the radiator cap when the engine is hot. Serious burns may occur from escaping high-pressure engine coolant. Wrap a thick cloth around the radiator cap, turn it a quarter turn to release pressure, then turn it fully.

1. Connect a drain hose. Use a general-purpose hose with dimensions: A: 8 mm (0.31 in), B: 300 mm (11.81 in).
2. Open the radiator drain plug (A) and remove the radiator cap. CAUTION: Perform this step when the engine is cold. If draining all coolant, open cylinder block drain plugs (Refer to EM-68, "Setting").
3. Remove the reservoir tank if necessary, drain coolant, and clean the tank before reinstalling. Refer to CO-14, "Exploded View".
4. Check drained coolant for contaminants (rust, corrosion, discoloration). If contaminated, flush the system. Refer to CO-10, "Flushing".
5. Disconnect the drain hose.

Refilling

CAUTION: Do not reuse O-rings. Do not add water leak preventive additives as they may clog the cooling waterways. Use Genuine NISSAN Long Life Antifreeze/Coolant (blue) or equivalent, mixed with distilled or demineralized water. Refer to MA-10, "Fluids and Lubricants".

1. Install the reservoir tank (if removed) and radiator drain plug. CAUTION: Clean the drain plug and install a new O-ring.
2. Ensure all hose clamps are tightened.
3. Remove the air duct (suction side). Refer to EM-25, "Exploded View".
4. Disconnect the vacuum hose from the brake booster side and remove the vacuum tube from the clamp. Refer to BR-37, "Exploded View".
5. Disconnect the heater hose (1) as shown in the figure. Enhance the heater hose position as high as possible.
6. Fill the radiator (1) to the specified level. CAUTION: Avoid spilling coolant on electronic equipment (alternator, etc.). Pour coolant slowly (less than 2 L/min) to allow air to escape. If coolant overflows from the disconnected heater hose, reconnect it and continue filling.

Engine Coolant Capacity:

• With reservoir tank at "MAX" level: M/T models: 7.9 L (8-3/8 US qt, 7 Imp qt); CVT models: 8.1 L (8-1/2 US qt, 7-1/8 Imp qt).
• Reservoir tank engine coolant capacity (At "MAX" level): 0.6 L (5/8 US qt, 1/2 Imp qt).

7. Refill the reservoir tank to the "MAX" level line with engine coolant.
8. Install the air duct (suction side). Refer to EM-25, "Exploded View".
9. Install the radiator cap.
10. Warm up the engine until the thermostat opens (approx. 10 minutes at 3,000 rpm). Check coolant flow by touching the lower radiator hose. CAUTION: Monitor the water temperature gauge to prevent overheating.
11. Stop the engine and allow it to cool down to below 50°C (122°F). Use the fan to speed up cooling. Refill radiator to the filler neck if necessary. CAUTION: Avoid spilling coolant on electronic equipment (alternator, etc.).
12. Refill the reservoir tank to the "MAX" level line.
13. Repeat steps 6 through 11 two or more times with the radiator cap installed until the coolant level stabilizes.
14. Check the cooling system for leaks while the engine is running.
15. Warm up the engine and listen for coolant flow sounds at various engine speeds (idle to 3,000 rpm) with the heater temperature controller set to "COOL" and "WARM". Sound may be noticeable at the heater unit. Repeat this step three times.
16. If sounds are heard, bleed air from the system by repeating steps 6 through 11 until the reservoir tank level no longer drops.

Flushing

1. Install the radiator drain plug. CAUTION: Clean the drain plug and install a new O-ring.
2. Remove the air duct (suction side), air cleaner cover, and air cleaner body. Refer to EM-25, "Exploded View".
3. Disconnect the vacuum hose from the brake booster side and remove the vacuum tube from the clamp.
4. Disconnect the heater hose (1) as shown in the figure. Enhance the heater hose position as high as possible.
5. Fill the radiator and reservoir tank with water and reinstall the radiator cap. If coolant overflows from the disconnected heater hose, reconnect it and continue filling.
6. Connect the vacuum hose and install the vacuum tube.
7. Install the air duct (suction side), air cleaner cover assembly, and air cleaner body assembly. Refer to EM-25, "Exploded View".
8. Run the engine and warm it up to normal operating temperature.
9. Rev the engine two or three times under no-load.
10. Stop the engine and wait until it cools down.
11. Drain water from the system. Refer to CO-8, "Draining".
12. Repeat steps 1 through 9 until clear water drains from the radiator.

Radiator

Radiator Cap: Inspection

• Check the valve seat (A) of the radiator cap.
• Verify the valve seat is not swollen such that the plunger edge is visible from the top.
• Ensure the valve seat is clean and undamaged.
• Pull the negative-pressure valve to open it and ensure it closes completely when released.
• Check the valve seat for dirt or damage.
• Verify the negative-pressure valve opens and closes correctly.
• Check radiator cap relief pressure. Standard and Limit: Refer to CO-26, "Radiator". Apply engine coolant to the cap seal surface when connecting to the tester (A) and adapter (B).
• Replace the radiator cap if any of the above checks reveal issues.

CAUTION: When installing the radiator cap, thoroughly wipe the radiator filler neck to remove any waxy residue or foreign material.

Radiator: Inspection

Check the radiator for mud or clogging. Clean as follows if necessary.

CAUTION: Be careful not to bend or damage radiator fins. If cleaning without removal, remove surrounding parts (cooling fan assembly, horns) and tape harnesses/connectors to prevent water entry.

1. Apply water vertically downward to the back side of the radiator core.
2. Apply water to all radiator core surfaces once per minute.
3. Stop washing when no more stains flow out.
4. Blow air into the back side of the radiator core vertically downward. Use compressed air at less than 490 kPa (4.9 bar, 5 kg/cm², 71 psi) from a distance of more than 30 cm (11.81 in).
5. Blow air into all radiator core surfaces once per minute until no water sprays out.

Removal and Installation

Radiator

Exploded View

Diagram shows radiator components including cooling fan assembly, mounting rubbers, radiator, drain plug, hoses, reservoir tank, clamps, water outlet adaptor, bracket, and radiator cap.

Component List:

• 1. Cooling fan assembly
• 2. Mounting rubber (upper)
• 3. Radiator
• 4. Mounting rubber (lower)
• 5. O-ring
• 6. Drain plug
• 7. Clamp
• 8. Radiator hose (lower) (LH)
• 9. Reservoir tank hose
• 10. Reservoir tank
• 11. Reservoir tank cap
• 12. Clamp
• 13. Radiator hose (upper)
• 14. Water outlet adaptor
• 15. Radiator cap
• 16. Radiator hose pipe
• 17. Bracket
• 18. Radiator hose (lower) (RH)
• A. To water outlet
• B. To water inlet
• Torque values are indicated in N·m (kg-m, in-lb).
• O-rings should always be replaced after every disassembly.
• Symbols indicate points connected to the actual vehicle.

Removal and Installation

Removal

WARNING: Never remove the radiator cap when the engine is hot. Serious burns may occur from escaping high-pressure engine coolant. Wrap a thick cloth around the cap, turn it a quarter turn to release pressure, then turn it fully.

1. Drain engine coolant from the radiator. Refer to CO-8, "Draining". CAUTION: Perform this step when the engine is cold. Never spill engine coolant on the drive belt.
2. Remove the engine cover. Refer to EM-24, "Exploded View".
3. Remove the engine under cover.
4. Remove the radiator hoses (upper and lower).
5. Remove the front bumper. Refer to EXT-11, "Exploded View".
6. Remove the radiator core support upper. Refer to DLK-123 or DLK-238.
7. Disconnect the cooling fan harness connector.
8. Remove the reservoir tank.
9. Remove the cooling fan assembly. CAUTION: Be careful not to damage or scratch the radiator core during removal.
10. Remove the condenser from the radiator and temporarily fasten it to the vehicle with a rope.
11. Pull up and remove the radiator assembly (1). CAUTION: Never damage the radiator core and condenser assembly core.

Installation

CAUTION: Do not reuse O-rings. Install in the reverse order of removal.

NOTE: Insert the radiator hose (1) fully to the stopper (2) or by 33 mm (1.30 in) if the hose has no stopper. Ensure correct orientation of hose clamps as shown in the figure. Dimension "A" for hose clamp installation should be 3 mm (0.12 in) from the end of the paint mark.

Inspection After Installation

• Check for engine coolant leakage using the radiator cap tester and adapter. Refer to CO-8, "Inspection".
• Start and warm up the engine. Visually check for any engine coolant leakage.

Cooling Fan

Exploded View

Diagram shows cooling fan components: fan motor, fan shroud, and cooling fan. Torque specifications and sealant application points are indicated.

Components:

• 1. Fan motor
• 2. Fan shroud
• 3. Cooling fan
• A. Apply sealant on fan motor shaft.
• Torque values are in N·m (kg-m, in-lb).
• Apply genuine high strength thread locking sealant or equivalent where indicated.

Removal and Installation

Removal

1. Drain engine coolant. Refer to CO-8, "Draining". CAUTION: Perform this step when the engine is cold. Never spill engine coolant on the drive belt.
2. Remove the engine cover.
3. Remove the front bumper. Refer to EXT-11, "Exploded View".
4. Remove the radiator core support upper. Refer to DLK-123 or DLK-238.
5. Disconnect the cooling fan harness connector.
6. Remove the reservoir tank. Refer to CO-14, "Exploded View".
7. Remove the radiator hose (upper). Refer to CO-14, "Exploded View".
8. Remove the cooling fan assembly. CAUTION: Be careful not to damage or scratch the radiator core when removing.

Installation

Install in the reverse order of removal. CAUTION: Use only genuine parts for fan shroud mounting bolts and observe specified torque to prevent radiator damage.

NOTE: Cooling fan operation is controlled by the ECM. Refer to EC-504, "Component Function Check" for details.

Disassembly and Assembly

Disassembly

1. Remove the cooling fan mounting nut and then remove the cooling fan.
2. Remove the fan motor.

Assembly

Assemble in the reverse order of disassembly. Apply genuine high strength thread locking sealant on the fan motor shaft.

Inspection After Disassembly

• Inspect the cooling fan for cracks or unusual bends.
• Replace the cooling fan if any defects are found.

Water Pump

Exploded View

Diagram shows the water pump and its gasket. Torque specifications are provided.

Components:

• 1. Gasket
• 2. Water pump
• Torque values are in N·m (kg-m, ft-lb).
• Gaskets should always be replaced after every disassembly.

Removal and Installation

Removal

1. Drain engine coolant from the radiator. Refer to CO-8, "Draining". CAUTION: Perform this step when the engine is cold. Never spill engine coolant on the drive belt.
2. Steer the front wheel to the right.
3. Remove the front fender protector (RH). Refer to EXT-21, "Exploded View".
4. Remove the drive belt. Refer to EM-18, "Exploded View".
5. Remove the water pump. Engine coolant will leak from the cylinder block; have a receptacle ready. CAUTION: Handle the water pump vane carefully to avoid contact with other parts. The water pump cannot be disassembled and must be replaced as a unit.

Installation

Install in the reverse order of removal.

Inspection After Removal

• Visually check the water pump body and vane (A) for dirt or rust.
• Check the vane shaft for looseness and ensure it turns smoothly by hand.
• Replace the water pump if necessary.

Inspection After Installation

• Check for engine coolant leakage using the radiator cap tester adapter and tester. Refer to CO-8, "Inspection".
• Start and warm up the engine. Visually check for any engine coolant leakage.

Thermostat

Exploded View

Diagram shows the thermostat housing, gasket, rubber ring, thermostat, water inlet, clamp, and radiator hose. Torque specifications are provided.

Components:

• 1. Thermostat housing
• 2. Gasket
• 3. Rubber ring
• 4. Thermostat
• 5. Water inlet
• 6. Clamp
• 7. Radiator hose (upper)
• A. To radiator
• Engine front
• Torque values are in N·m (kg-m, ft-lb).
• Parts should always be replaced after every disassembly.

Removal and Installation

Removal

1. Drain engine coolant from the radiator. Refer to CO-8, "Draining". CAUTION: Perform this step when the engine is cold.
2. Remove the intake manifold. Refer to EM-27, "Exploded View".
3. Disconnect the radiator hose (lower) (RH) from the water inlet. Refer to CO-14, "Exploded View".
4. Remove the water inlet and thermostat. Engine coolant may leak from the cylinder block; have a receptacle ready.

Thermostat Housing

1. Drain engine coolant. Refer to CO-8, "Draining".
2. Remove the alternator. Refer to CHG-22, "Exploded View".
3. Remove the water pump. Refer to CO-19, "Exploded View".
4. Disconnect the water hose and remove the thermostat housing.

Installation

Install in the reverse order of removal.

Thermostat Installation

• Install the thermostat with the rubber ring (1) groove fitted to the thermostat flange (A) circumference.
• Install the thermostat (2) with the jiggle valve (A) facing upwards.

Thermostat Housing Installation

Install in the reverse order of removal.

Inspection After Removal (Thermostat)

• Place a thread (A) to catch in the thermostat valves (1). Immerse in a container (B) of water and heat while stirring.
• The valve opening temperature is when the valve opens and falls from the thread.
• Continue heating and check the full open valve lift amount.
• After checking maximum lift, lower the water temperature and check the valve closing temperature.
• Standard: Refer to CO-26, "Thermostat".
• If out of standard, replace the thermostat.

Inspection After Installation

• Check for engine coolant leakage using the radiator cap tester adapter and tester. Refer to CO-8, "Inspection".
• Start and warm up the engine. Visually check for any engine coolant leakage.

Water Outlet

Exploded View

Diagram shows components of the water outlet assembly, including heater pipe bracket, radiator cap, water outlet adaptor, clamps, hoses, water outlet, engine coolant temperature sensor, gasket, and rubber ring. Torque specifications are provided.

Components:

• 1. Heater pipe bracket
• 2. Radiator cap
• 3. Water outlet adaptor
• 4. Clamp
• 5. Water outlet hose
• 6. Clamp
• 7. Hose
• 8. Clamp
• 9. Water outlet
• 10. Clamp
• 11. Heater hose
• 12. Clamp
• 13. Heater hose
• 14. Hose
• 15. Clamp
• 16. Engine coolant temperature sensor
• 17. Gasket
• 18. Rubber ring
• 19. Water control valve
• 20. Gasket
• A. For CVT models
• B. To reservoir tank
• C. To electric throttle control actuator
• D. To radiator hose (upper)
• E. To CVT oil warmer
• F. To heater hose
• G. To heater hose
• H. To turbocharger inlet tube
• Torque values are in N·m (kg-m, ft-lb).
• Parts should always be replaced after every disassembly.

Removal and Installation

Removal

1. Drain engine coolant from the radiator. Refer to CO-8, "Draining". CAUTION: Perform this step when the engine is cold.
2. Remove the engine cover. Refer to EM-24, "Exploded View".
3. Remove the battery. Refer to PG-95, "Exploded View".
4. Remove the air duct (upper) and air cleaner cover/body assembly.
5. Disconnect the radiator hose (upper). Refer to CO-14, "Exploded View".
6. Remove the water outlet adaptor.
7. Disconnect engine harness connectors around the battery.
8. Remove bracket (2) and disconnect engine harness clip (transmission side and water outlet side). 1: Engine harness.
9. Disconnect the crankshaft position sensor harness connector.
10. Move the engine harness and secure the service area.
11. Remove the water hose from each water outlet connection and the heater hose.
12. Remove the water outlet.
13. Remove the engine coolant temperature sensor from the water outlet, if necessary.

Installation (Water Control Valve)

Install in the reverse order of removal. Install the water control valve with the rubber ring (1) groove fitted to the water control valve flange (A) circumference. Install the water control valve (2) with the arrow (A) facing up and the frame center part (B) facing upwards.

Inspection After Removal (Water Control Valve)

• Place a thread (A) to catch in the water control valve valves (1). Immerse in a container (B) of water and heat while stirring.
• The valve opening temperature is when the valve opens and falls from the thread.
• Continue heating and check the continuous valve lifting toward maximum lift.
• NOTE: The maximum valve lift amount standard temperature for the water control valve is a reference value.
• After checking maximum lift, lower the water temperature and check the valve closing temperature.
• Standard: Refer to CO-26, "Water Control Valve".
• If out of standard, replace the water control valve.

Inspection After Installation

• Check for engine coolant leakage using the radiator cap tester adapter and tester. Refer to CO-8, "Inspection".
• Start and warm up the engine. Visually check for any engine coolant leakage.

Service Data and Specifications (SDS)

Periodical Maintenance Specification

Engine Coolant Capacity (Approximate)

Radiator

Thermostat

Water Control Valve