The "Official" Tests:
Testing and Inspection
SPIN TEST
If the fan assembly free-wheels without drag (the fan blades will
revolve more than five turns when spun by hand), replace the fan drive.
This spin test must be performed when the engine is cool.
NOTE: For the following test, the cooling system must be in good
condition. It also will ensure against excessively high coolant
temperature.
FUNCTION TEST
Drill a 3.18 mm (1/8 inch) diameter hole in the top center of the fan
shroud.
Obtain a dial thermometer with an 8 inch stem (or equivalent). It should
have a range of -18配o 105蚓 (0配o 220蚌) . Insert thermometer through
the hole in the shroud. Be sure that there is adequate clearance from
the fan blades.
Connect a tachometer and an engine ignition timing light (timing light
is to be used as a strobe light).
Block the air flow through the radiator. Secure a sheet of plastic in
front of the radiator (or air conditioner condenser). Use tape at the
top to secure the plastic and be sure that the air flow is blocked.
Be sure that the air conditioner (if equipped) is turned off. WARNING:
USE EXTREME CAUTION WHEN THE ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS
OR FAN. DO NOT WEAR LOOSE CLOTHING.
Start the engine and operate at 2400 rpm . Within ten minutes the air
temperature (indicated on the dial thermometer) should be up to 88蚓
(190蚌) . Fan drive engagement should have started to occur at between
74配o 82蚓 (165配o 180蚌) . Engagement is distinguishable by a definite
increase in fan flow noise (roaring). The timing light also will
indicate an increase in the speed of the fan.
When the air temperature reaches 88蚓 (190蚌) , remove the plastic
sheet. Fan drive disengagement should have started to occur at between
57配o 79蚓 (135配o 175蚌) . A definite decrease of fan flow noise
(roaring) should be noticed. If not, replace the defective viscous fan
drive unit.
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of jay & dana
Sent: Friday, March 21, 2003 5:08 PM
To: dakota-truck@dakota-truck.net
Subject: DML: Clutch fan
So how does one go about determining if the clutch fan is screwed? On
my 97 since day 1, I get the initial roar at start-up when cold
(sometimes) and also even when it's warmed up and even in the summer I
will get that slight roar upon slow acceleration or deceleration (at
slow speeds) when turning etc. just for a second or two. Since it's
happened ever since I've had my truck I thought this was normal. Any
ideas on the best way to determine if it's faulty or not?
TIA
Jay
> I need an opinion. I just took my 2K QC 4.7 5 speed
> w/ 48K miles, into my dealer to have my clutch fan
> replaced and had them check the brakes.
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:46:01 EST