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SERIES 4000 12/16V SERVICE MANUAL
Fan Clutch Cycles Off and On Continuously at an Abnormally High Rate
Perform the following corrective actions to resolve fan clutch cycles off and on continuously
at an abnormally high rate:
1. Coolant level is low.
Fill radiator to proper level. Go to step 2 for a further probable cause.
2. Heat range setting of thermostat and thermal sensor is not compatible.
Replace either thermostat or thermal sensor with correct temperature setting to obtain
proper sequence of operation.
Noisy Operation
Perform the following corrective actions to resolve noisy operation:
1. Noise originating elsewhere, but "telegraphing" to appear as though the fan or the fan
clutch is noisy.
On some engines, a severe noise originates in the air conditioner compressor and
telegraphs through belts to be heard in the fan clutch. Go to step 2 for further checking.
If no noise is present, fan clutch is OK.
2. Internal failure.
Move fan blade in and out between engine and radiator. There should be no
forward-rearward movement of the fan mounting hub. If movement exists, repair the
fan clutch.
All information subject to change without notice.
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Copyright © DETROIT DIESEL CORPORATION
Summary of Contents for 4000 Series
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Page 2631: ...E TROUBLESHOOTING Section Page E 010 MECHANICAL TROUBLESHOOTING E 3 E 020 TESTING E 45 ...
Page 2681: ...F PREVENTIVE MAINTENANCE Section Page F 010 Rockford Fan Clutch F 3 ...