Detroit Diesel 4000 Series, Service Manual, Page: 2638 / 2706

SERIES 4000 12/16V SERVICE MANUAL
E 011.02 – FAULT CONDITIONS
Engine Runs Hot and Fan Will Not Lock Up
Perform the following corrective actions to resolve engine runs hot and fan will not lock up:
1. Fan clutch will not lock up.
Visually verify that the fan is not locked up. A locked-up fan running at high speed will
create a significantly greater air flow (and noise level) than will a free-wheeling fan. The
problem may be located in a component system other than the fan clutch.
To avoid injury when working near or on an operating
engine equipped with a hydraulic clutch fan:
3
Never work in close proximity to the fan.
3
Never try to keep the fan from rotating by holding the
fan.
3
Never tie down the fan with straps, chains, or other
restraints.
3
Never shut off the oil supply to the fan clutch.
To avoid injury when working near or on an operating
engine equipped with a hydraulic clutch fan, remove loose
items of clothing and jewelry; tie back or contain long hair
that could be caught in any moving part causing injury. A
hydraulic fan may start without warning.
Disconnect the solenoid wires at the harness connector to lock up the fan clutch. Check
fan lockup with a strobotac. Match-mark the fan and fan clutch pulley. The two marks
should rotate at exactly the same speed. If they do not, the fan clutch is not completely
locked up. Go to step 2 for a further probable cause.
2. Coolant level may be low.
Fill radiator to correct coolant level. Go to step 3 for a further probable cause.
3. Fan belt is slipping during engine operation.
Properly tension a loose belt; refer to section C 221.05.11C 221.05.11 . Replace the belt if
it is worn. Repair or replace belt tensioning mechanism if necessary. Check the pulley
grooves to insure there is no excessive wear. Go to step 4 for a further probable cause.
4. There may be electrical wiring problems.
All information subject to change without notice.
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