Usage:
5-1 Cooling Fan
5-1-1 Removal and Installation
- 1 Cooling fan
- 2 Spacer
- 3 Water pump pulley
- 4 V-belt
- 2 Spacer
<D3: Option>
- 1 Cooling fan
- 2 Auto cool fan coupling
- 3 Water pump pulley
- 4 V-belt
- 2 Auto cool fan coupling
5-1-2 Inspection of Auto Cool Fan Coupling <Option: D3>
The auto cool fan coupling is a non-maintainable assembly requiring no silicone oil maintenance and it must be replaced as an assembly if defective.
(1) While the engine is cold, move the entire fan coupling unit in the axial direction. If there is an excessive play, the bearing is defective requiring replacement.
(2) Carefully turn the fan by hand. If the fan turns more than the limit even when you let it go, replace the auto cool fan coupling.
While the fan is turning, ensure that the bearing rotates smoothly.
(3) If there is mud, dust, or dirt on the bimetal, clean with wire brushes.
NOTE: Do not apply excessive force to the bimetal during cleaning.
5-2 Water Pump
5-2-1 Removal and Installation
- 1 Bypass hose
- 2 Water pump assembly
5-2-2 Disassembly and Inspection
(1) D3
<Disassembly sequence>
For disassembly of parts with an encircled number, see following items.
(a) Using gear puller, remove the flange.
(b) After removing the snap ring, withdraw the water pump shaft together with the ball bearing by using a press and remove the impeller. Heating the water pump case to approximately 80°C helps make the job easier.
(c) Check the unit seals installed in the impeller and water pump case for damage and wear. If defects are evident, or when water leaks during operation, replace the unit seals with new ones.
NOTE: Whenever the unit seal is removed, it must be replaced with a new one.
When the unit seals alone are to be replaced, tap two holes in the impeller to M8 and, using Water Pump Impeller Puller (special tool), remove the impeller.
(d) Using a gear puller or press, remove the ball bearings.
NOTE: Do not remove the snap ring from the water pump shaft.
(e) When the impeller and flange are removed from the water pump shaft, it may result in insufficient interference. If they are reassembled three times or more, or if the interference is below the specification even reassembly is two times or less, they must be replaced with new ones.
(2) DR
<Disassembly sequence>
For disassembly of parts with an encircled number, see following items.
(a) Remove the flange with Puller (special tool).
(b) Remove the snap ring and, using a press, remove the water pump shaft with the ball bearing to remove the impeller.
Heating the water pump case to about 80°C makes the job easier.
(c) Check the unit seal fitted into the impeller and water pump case for damage and wear. If defects are evident, or if water leaks during operation, replace the unit seal.
NOTE: Whenever the unit seal is removed, it must be replaced with a new one.
When the unit seals alone are to be replaced, tap two holes in the impeller to M8 and, using Water Pump Impeller Puller (special tool), remove the impeller.
(d) Using a gear puller or press, remove the ball bearings.
NOTE: Do not remove the snap ring from the water pump shaft.
(e) When the impeller and flange are removed from the water pump shaft, it may result in insufficient interference. If they are reassembled three times or more, or if the interference is below the specification even reasembly is two times or less, they must be replaced with new ones.
5-2-3 Reassembly
(1) D3
NOTE:
1. After reassembly, install the water pump onto the timing gear case and make sure that the impeller is not in contact with the timing gear case.
2. Reassembly of the flange and impeller into the water pump shaft is allowed up to two times.
(2) DR
NOTE:
1. After reassembly, turn the water pump shaft by hand and make sure that the impeller is not in contact with the case and cover.
2. Reassembly of the flange and impeller into the water pump shaft is allowed up to two times.
5-3 Thermostat
5-3-1 Removal and Installation
- 1 Thermostat cover
- 2 Thermostat
- 3 Thermostat case
- 4 Bypass pipe
- 2 Thermostat
- 1 Thermostat cover
- 2 Thermostat
- 3 Water outlet pipe
- 2 Thermostat
5-3-2 Inspection
Agitate water in the container with the stirrer to obtain uniform temperature. For the inspection, use the following procedures.
(1) Slowly heat water to the thermostat valve opening temperature.
Keep this condition for about five minutes and make sure that the valve is open.
(2) Raise the water temperature up to 95°C.
Keep the condition for five minutes and measure the lift of pellet.
(3) Lower temperature down to 65°C or below and ensure that the valve is fully closed.
If the thermostat is found defective in any of the above items, replace it with a new one.
NOTE: Support the thermostat so that the heat will not directly transfer to it.
5-4 Radiator
5-4-1 Inspection
(1) Using a copper wire or similar device, remove dirt, mud, and bugs from the front of radiator core with care to prevent damage to tubings.
(2) Connect a hose to one of the radiator ports, cap the other port, and immerse the radiator into water. Using a radiator cap tester, force the compressed air under the specified inspection pressure from the hose end to check for leaks.
If there is a leak, resolder the point of leakage or replace the radiator.
(3) Inspection of Radiator Cap
Check the spring tension and sealing condition of the pressure valve and vent valve. If defective, replace.
Check the pressure valve opening pressure, using a radiator cap tester.
5-5 Inspection and Adjustment of V-belt Tension
(1) Adjust the belt tension to obtain the specified belt deflection when the center of each belt is pressed with a force of approximately 98 N (10 kgf).
NOTE:
1. A slack belt can be a cause of overheating and undercharge.
2. An excessively tight belt may result in damaged bearings and belts.
(2) Adjustment of Fan Belt
To adjust the fan belt tension, slightly back off the alternator attaching nut and adjusting bolt and move the alternator.
5-6 Cleaning of Cooling System
If the radiator is used for a long time, rust, scale, mud, etc. are deposited inside, resulting in overheat. Clean the cooling system with city water by using the following procedures.
The city water to be used should have the following properties.
Required Properties of City Water
NOTE:
1. Use a cleaning solution if the radiator is seriously obstructed or coolant is seriously contaminated.
2. When the cooling system is cleaned or washed with water, make sure that the coolant temperature is maintained at 90°C; the coolant temperature below the valve opening temperature closes the thermostat resulting in poor coolant circulation.
(1) Washing with Water (Every six months at coolant change or before and after the use of antifreeze)
(a) Discharge coolant from the radiator, and crankcase.
(b) After draining the system, fill it with tap water (preferably hot water) and, with the water temperature kept at around 90°C, run the engine at idle for about 10 minutes. Then, discharge water.
Continue flushing until the drained water runs clear.
(2) Washing with Cleaning Solution (Radipet-7 or equivalent) (When radiator clogging or coolant contamination are serious)
(a) Discharge coolant from the radiator and crankcase.
(b) Ready a mixture of Fuso Radiator Cleaner (Radipet-7 or equivalent: 5 to 10%) and cooling water.
Pour the specified amount of mixture into the radiator.
(c) Run the engine to raise the solution temperature to around 90°C. Let the engine run at idle for another 30 minutes, then remove the solution.
(d) After discharging the solution, fill the system with tap water (preferably hot water) and, with the water temperature kept at around 90°C, run the engine at idle for about 10 minutes. Then, drain water.
Continue flushing until the drained water runs clear.
(3) Antirust and Antifreeze
(a) After cleaning, add the Fuso Radiator Antirust (Radipet-9B) or equivalent at a ratio of 5% to the coolant quantity to prevent corrosion in summer.
(b) In winter, add the Fuso Antifreeze or equivalent at a ratio of 30 to 60% to prevent freezing.
NOTE:
1. Make sure that the antirust is added in summer and the antifreeze in winter at the specified ratios.
2. The antifreeze or antirust added coolant used for a season (about six months) must not be reused.
3. Use the antifreeze at a proper mixing ratio of 30 to 60% suitable for the atmospheric temperature. If the mixing ratio is less than 30%, the antirust effect will fall. If the ratio exceeds 60%, the antifreeze effect will fall, and engine overheating will result.
5-7 Gas Leak Test
Air or exhaust gas leaked into the coolant promotes corrosion and rust formation. Perform the following check and, if defects are found, take remedial action.
(1) Inspection
Remove the pressure cap from the radiator, and run the engine to raise the coolant temperature up to around 90°C.
If bubbles continue forming in the coolant under the condition, it indicates that air or exhaust gas has leaked into the coolant.
(2) Causes
(a) If air is trapped in coolant, check cylinder head bolts, water pump mounting bolts, and hose and its connections for looseness. Check also hoses for damage.
(b) If the exhaust gas has leaked into coolant, check the cylinder head gasket or nozzle tube end stake <4D31, 4D31-T> for damage. Check also cylinder head for cracks.
5-8 Bleeding the Cooling System
(1) With the pressure cap removed from the radiator, let the engine run at idle with coolant temperature of about 90°C to bleed the system completely.
(2) After the system has been bled of air, add coolant to radiator as required.