2. Check the torque of fan drive-to-pulley, hub and bracket assembly fasteners.
3. Check the torque of pulley, hub and bracket assembly-to-engine fasteners.
4. Check the fan drive, fan blade assembly, shroud, radiator, and the immediately adjacent areas for
evidence of interference between rotation and non-rotation parts. If damage is present, isolate and
repair the problem and replace defective parts.
5. By hand, rotate the fan at least one rotation (360 degrees.) It should turn smoothly, but with some
internal resistance. If the rotation of the fan results in a strong or non-uniform resistance, replace the
fan drive. Ensure the fan does not contact other objects.
6. Grasp the fan blade tip, and apply fore and aft pressure. At 10 inches (254 mm) radius from the
center, the blade tip should not move more than 1/16 inch (1.6 mm). If the blade moves more than specified and the excess cannot be attributed to pulley/water pump bearing wear, fan blade deflection, or loose fasteners (fan to fan drive or fan drive to hub/pulley), replace the fan drive. The previous step is used to detect looseness in the fan or fan drive mounting; when performing these steps, do not force the blade tip (cause the blade to deflect) because this will distort the resulting measurement.
7. Check for obstructions in the radiator, charge air cooler, air conditioning condenser, and transmission cooler if equipped. Remove any dirt, bugs, lint, or debris in the air path from the radiator to the engine. Pressure wash if necessary. To prevent damage, do not direct high-pressure spray onto the fan drive bi-metal. Also, the high-pressure wash must be directed squarely at the front, or rear, of the radiator and other coolers to prevent fin damage.
8. Ensure the cooling system is properly filled with the correct coolant mixtures (do not exceed 60% ethylene glycol) Warming up a cold engine prior to test preparation will shorten the run-time during the test procedure.
9. If engine is cold, start engine and:
a. Turn air conditioning OFF.
b. Turn heater OFF (NOTE: on buses, turn heater supply valves
OFF at the engine).
c. Run until thermostat opens; then turn engine OFF. Nylon fan blades
(yellow in color) may require painting with flat black paint in order to
Figure 1 Placement of Reflective Tape
1. Reflective tape on fan blade
2. Reflective tape on fan drive shaft
measure fan speed.
10. Apply a strip of reflective tape to one blade of the fan and another strip to the fan drive shaft so that
fan RPM and fan drive shaft RPM can be measured with the digital photo-tachometer. (Figure 1)
11. Connect electronic thermostat. If testing a non-electronic engine, measure coolant temperature with an accurate thermometer.
12. Fabricate a cardboard cover that covers the entire frontal area of the radiator. Cut a 5-inch (12.7 cm) hole in the area that aligns with the fan drive bi-metal. Position the cardboard in front of the radiator and tape as necessary to hold in place.
13. Carefully position the temperature probe so that it measures air temperature within 1 inch (2.54 cm) of the fan drive bi-metal. You can safely insert the probe through the A/C condenser, CAC, and radiator core. (Figure 2 and Figure 3)
14. Start the engine and
a. Recheck to ensure the air conditioning and heater are still OFF
(on buses, turn heater supply valves OFF) b. Turn electrical loads ON (lights, etc)
15. Raise the engine speed until the fan drive shaft reaches 2500 RPM (measured with a digital photo-tach). Do not measure the fan speed yet. The fan drive shaft speed is not the same as engine speed. Bright sunlight may make it difficult to read RPM measurements using the photo-tachometer.
16. Lock the throttle at this RPM (use PTO/cruise switches if available). This establishes the fan drive shaft TEST RPM. If engine cannot achieve 2500 RPM fan drive shaft input speed, test at the highest obtainable RPM.
17. Measure fan blade speed with the digital photo-tachometer (Figure 4) If the vehicle is equipped with shutters, they should open automatically before the fan drive engages.
18. As the engine is warming up:
a. The fan RPM should stabilize between 800 and 1000 RPM. Some
DD-30 and DD-34 fan drives may stabilize at up to 1300 RPM.
Refer to Table 1 for fan drive information.
b. As engine coolant temperature reaches 200- 220°F
(93.3-104.4°C)(Figure 5), fan speed should increase to 2125 RPM
or higher (85% or more of the test RPM).
c. The air temperature at the bi-metal should be between 165°F (73.9°C)
and 195°F (90.6°C) when the fan engages (Figure 5).
Refer to Table 1 for specific fan drive P/N calibration information. 19. With the fan engaged, record fan RPM, coolant temperature,
and air temperature at bi-metal.
20. With the fan engaged, maintain the TEST RPM, by keeping the engine
speed constant. As temperatures decrease, fan speed should begin to decrease. After 2-3 minutes the fan should slow to the initial fan speed (approximately 40% of the TEST RPM).
21. Allow fan to repeat this cycle several times while recording temperatures and fan RPM.
Tryed all this
I will try this part of the forum lol
