18 4 DLT ENGINE PROCEDURE FOR CHECKING AN EATON VISCOUS FAN DRIVE IN A VEHICLEWORKSHOP This procedure will only give an indication that the fan drive is cutting in and out, but will not be able to check the accuracy of the cut in temperature. Please use this procedure in conjunction with the description on the operation of the fan drive. All BorgWarner (Eaton) fan drives work in the same method and have similar mechanical construction.The only differences are the size of the fan drive and the external appearance. Depending on the level of test equipment available there are several ways of checking if the fan drive is working correctly. Using a stroboscope. I. With the engine running under no load conditions for approximately 3minutes, for example at 2,000 rpm, observe the fan drive speed with a stroboscope. In the disengaged mode the fan speed should be approximately 800 rpm. By running for three minutes it will ensure that the fan drive has pumped out the silicone fluid into the reservoir and that the fan drive will be in the cut out ( idle ) condition. 2. Either a) Blank the radiator by using a sheet of cardboard which has a 15 cm hole cut out of it in line with the centre of the fan drive. This will allow a flow of air on to the bimetal coil, and the cardboard will allow the radiator to heat up quicker. Keep a check on the vehicle temperature gauge and let the water temperature rise to about 1050 C.This will ensure that the fan drive will engage. (Depending on the pressure of the water system let the temperature rise higher) b) Using a commercial hot air blower, which will provide a hot air flow of at least 750 C, direct the air on to the centre of the fan drive through the radiator. Keep the hot air on for several minutes. This will cut the fan drive in, and the fan speed Will increase. It is important that the blower is powerful to ensure that the hot air reaches the fan drive at the correct temperature. Test procedure for fan drive 3. Once the fan drive has become engaged by either method in 2, check the fan speed with a stroboscope . At 2000 rpm input speed the fan speed should be about 1800 rpm.This may vary depending on the actual application. Testing without a stroboscope 4. Use the same method described in section 2. but this time listen to the noise level generated by the fan. With the fan in the idle condition the noise level should be very low, however when the fan speed increases in the engaged mode there will be a significant roar from the fan. This will dearly indicate if the fan drive is working. 5. If the fan drive fails to engage during these tests there may be something wrong with the fan drive. The unit should be replaced.
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