4
FIGURE 9
LINE HAUL VEHICLES:
Every 25,000 miles, 900 hours, or three months - whichever
occurs first-lubricate the FD-1
™
clutch (SEE NOTE).
Every 50,000 miles, 1,800 hours, or every six months
whichever occurs first-perform the service checks outlined
in this manual.
CITY DELIVERY
Every 15,000 miles, 300 hours or two months - whichever
occurs first:
1. Perform the service checks outlined in this manual.
2. Lubricate the FD-1
™
clutch (SEE NOTE).
NOTE: Prior to July, 1980, a grease provision was optional.
When this option was not included, permanently
lubricated components were installed. Most fan
clutches produced after July, 1980, include the
grease provision as a standard feature.
Lubricate the FD-1
™
clutch with approximately 10 cubic
centimeters of CHEVRON SRI #2 or an equivalent grease.
SERVICE CHECKS
Before performing the operational and leakage checks,
apply the vehicle parking brakes or chock the wheels.
OPERATIONAL
1. With the engine cold, the ignition off and at least 75 psi
air pressure in the brake system, note that the fan is
disengaged from the pulley and can be turned by hand.
If the fan can be turned, proceed to step #2. If it cannot
be turned:
A. Drain all reservoirs and disconnect the air control
line leading to the fan clutch and apply at least 75
psi shop air pressure to the fan clutch.
B. If the fan cannot be turned, the clutch is defective
and must be repaired or replaced (see appropriate
section of this manual).
C. If the fan can now be turned; check the air lines
leading to and from the thermostatic control valve
for “kinks” or obstructions, and check the control
valve itself according to the manufacturer’s
instructions.
2. After performing check #1, drain all air pressure from the
brake system. Note that the fan is now engaged and
cannot be turned by hand. If it cannot be turned, proceed
to test #3. If it can be turned, the clutch is defective and
must be repaired or replaced.
3. Check the operation of the thermostatic control valve by
running the engine up to operating temperature. Note
that the fan clutch engages when engine temperature
rises to normal or above and disengages after fan
cooling is accomplished. Normal engagement time
should not exceed two minutes. If engagement time does
not exceed two minutes, proceed to check #4. If
engagement time does exceed two minutes:
A. If this test is being performed for the first time after
installation of the fan clutch, recheck the setting of
the thermostatic control valve and compare it with
the setting of the engine coolant thermostat or in
the case of vehicles with radiator shutters, with the
setting of the shutter control. The fan clutch control
should always be 10° higher than the highest setting.
B. If the fan clutch installation has successfully passed
this test before, but does not do so now, the
thermostatic control valve is defective and should
be replaced.
4. Check the condition of the rear main bearings during
operation and note any excessive wobble or noise. The
pressure plate ball bearing and sliding piston can be
checked while the engine is off and the fan is
disengaged. “Rock” the fan from front to back at the
outer tip of the blade. If movement of the blade tip, front
to back, exceeds 3/8" (See fig. 5) the fan clutch must
be repaired or replaced.
5. Check the pressure plate lining thickness by measuring
the gap between the pressure plate edge and the pulley
face with the clutch engaged. The gap should not be
less than .120 inch or approximately 1/8 inch.
LEAKAGE CHECKS
In order to check for air leakage past the only two sliding
o-rings in the FD-1
™
fan clutch, it is necessary to disconnect
the single air control line.
Check for leakage by connecting a 90 cu. in. reservoir (Bendix
part number 225000) with a gauge installed to the control
(9) (8) (13)
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(1)
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