Bronco Full Size L6-300 4.9L (1987)
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A force greater than eight (8) ounces may deflect the fan blade with erroneous results.
d.
Replace the fan clutch if more than 2/10" (5.1 mm) of movement is observed. Refer to the Dealer Master Parts Catalog for correct parts
usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
e.
If this is not the concern, go to Step 5.
5.
Install a temporary engine tachometer if the vehicle is not equipped with a tachometer.
NOTE:
DURING THE FOLLOWING TESTS, BE SURE TO MONITOR THE ENGINE COOLANT TEMPERATURE BY THE TEMPERATURE GAUGE
IN THE INSTRUMENT CLUSTER. SHUT OFF THE ENGINE IF THE TEMPERATURE RISES ABOVE THE MAXIMUM RECOMMENDED
LIMIT FOR THE ENGINE OR IF COOLANT IS DISCHARGED OUTSIDE THE SYSTEM. THE TESTS CAN BE RESUMED USING THE
FOLLOWING PROCEDURES AFTER THE COOLANT TEMPERATURE DROPS TO A NORMAL OPERATING LEVEL.
NOTE:
IF THE HOOD IS LEFT OPEN, THE FAN NOISE MAY BE EASIER TO HEAR.
WARNING:
DO NOT STAND IN LINE WITH THE FAN.
6.
Start the engine.
7.
Check for fan disengagement and be aware of the following operational characteristics.
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The fan clutch may be engaged when the engine is first started. This will be apparent from the noise level of the fan which has a distinctive
roar.
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The fan clutch engagement is due to the viscous silicone fluid draining back and filling the gap between input and output components.
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Running the engine at a constant speed of about 2000 rpm should pump the fluid back to its reservoir, disengaging the fan clutch after no
more than five minutes.
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As the fan speed declines, the noise will drop off to a level inaudible to most observers.
a.
Continuing the test, if the fan clutch does not reengage after five more minutes at 2000 rpm, the fan clutch should be replaced. Refer to the Dealer
Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
b.
Repeat the test procedure after fan clutch replacement to confirm the fix and to assure customer satisfaction.
c.
If this is not the concern, go to Step 8.
8.
Stop the engine.
a.
Cut and install a piece of cardboard large enough to cover the front of the radiator with a six inch diameter hole in line with the fan clutch.
b.
If it is not possible to install the cardboard directly against the radiator, attach it to the A/C condenser.
9.
Start the engine.
a.
With the gas engine at 2700 to 3000 rpm or diesel engine at 2100 to 2300 rpm, the vehicle temperature gauge will rise steadily as the engine
warms and then appear to level off for a short time when the thermostat opens.
b.
Make note of the temperature gauge position when the thermostat opens. The engine coolant temperature will continue to rise until the fan
clutch engages.
10.
Check for fan engagement...
a.
Continue to observe the coolant temperature gauge. As the fan clutch engages, the fan noise will continue to increase and then level off at
full engagement. The fan clutch may cycle off-and-on a few times during the initial engagement.
b.
If the fan clutch does not engage before the maximum indicated safe operating engine coolant temperature is reached, it should be replaced.
Refer to the Dealer Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
c.
Repeat the test procedure after fan clutch replacement to verify the fix and to assure customer satisfaction. The rate of rise of the coolant
