6.7 cooling fan problem

[Tater2009]

hi guys. I have a 2011 6.7 with 18000 miles, the cooling fan is on every time i start it and when i drive off it roars for a min then goes off. Then every time i stop for more then a min it is back on and does the same thing. so annoying. Ford put a new clutch fan and same thing. anyone else have this problem. Thanks.

[BWER]

Bad troll is a bad troll.

[ars5147]

Originally Posted by BWER

Bad troll is a bad troll.

Some people might actually have 6.7s that break. What if it's the new 6.0 and it's to early to know?

Kidding aside, check the obvious like wiring harness connections, look for chafed wires. Could be a bad temp sensor. Then go back to the dealership and demand answers.

[stltikn]

Have the radiator cap pressure tested. Todays caps are NOT as reliable as caps of 20 yrs ago. Everyone should have their caps tested periodically. I believe it's 4 degrees of temp rise for every pound of pressure loss. Someone can check me on the exact figure. The de-clutching fan should engage briefly when cold then disengage and only re-engage when it sees its set temp.

[jesilvas]

Originally Posted by stltikn

Have the radiator cap pressure tested. Todays caps are NOT as reliable as caps of 20 yrs ago. Everyone should have their caps tested periodically. I believe it's 4 degrees of temp rise for every pound of pressure loss. Someone can check me on the exact figure. The de-clutching fan should engage briefly when cold then disengage and only re-engage when it sees its set temp.

What does that have to do with the fan clutch? If it does it right at start up, then the coolant is very close to ambient temp to start with.

Originally Posted by BWER

Bad troll is a bad troll.

Says the man with one post

Originally Posted by Tater2009

hi guys. I have a 2011 6.7 with 18000 miles, the cooling fan is on every time i start it and when i drive off it roars for a min then goes off. Then every time i stop for more then a min it is back on and does the same thing. so annoying. Ford put a new clutch fan and same thing. anyone else have this problem. Thanks.

The 7.3 did that and Ford put out a TSB or a little note about it, calling it morning sickness. For real.
But that's a viscous fan clutch. If the 6.7s went back to a viscous clutch, that would be the issue. If not and they are electrically controlled, then I'd bet it's a sensor somewhere.

[M90Ranger]

It's NORMAL. They all do it till fully warmed up. The colder it is out the longer they do it.

[jesilvas]

But why? Are they viscous clutches?

[M90Ranger]

Originally Posted by jesilvas

But why? Are they viscous clutches?

Yes It is Viscous Electronic
I Actually replaced one because my manager at the time said to, and it made no difference.
The Newer Calibrations seem to do it more though.
Here's the Description and Pinpoint test:

AH3 : CHECK THE COOLING FAN OPERATION
NOTE: Inherent to viscous clutches is a delay in transitioning from a low to a high speed or from a high to a low speed. This delay is dependent upon engine speed, starting fan speed and clutch temperature. With the engine at operating temperature and at 2,500 RPM, the delay should be less than 30 seconds.

NOTE: The time required to change fan speed, once a command is issued by the PCM,
varies depending on operating conditions such as temperature, engine speed and starting fan speed.

The reaction time can be from seconds to several minutes depending on the test
conditions.
NOTE: The calibration limits the engine RPM when using output state control. The engine
RPM must be increased using the accelerator pedal to reach the required RPM for this test.
Ignition ON, engine running.
Access the PCM and monitor the FANSS (RPM) PID.
Access the PCM and monitor the RPM (RPM) PID.
Engine at normal operating temperature.
Increase the engine speed to 2,500 RPM using the accelerator pedal.
Access the PCM and control the FANDC (PER) PID.
Decrease the commanded cooling fan duty cycle to 0%.
Allow the fan speed to stabilize below 600 RPM.


Cooling Fan
The cooling fan and viscous drive actuator valve controls the fluid flow from the reservoir into the working chamber. Once viscous fluid is in the working chamber, shearing of the fluid results in fan rotation. The valve is activated by a pulse width modulation (PWM) output signal from the powertrain control module (PCM). By opening and closing the fluid port valve, the PCM controls the fan speed. Fan speed is measured through a Hall effect sensor, and is monitored by the PCMduring closed loop operation. The PCM optimizes the fan speed based on the engine coolant temperature, the engine oil temperature, the fuel rail temperature, the transmission fluid temperature, the intake air temperature, or air conditioning requirements.
When an increased demand for fan speed is requested for vehicle cooling, the PCM monitors the fan speed through
the Hall effect sensor. If a fan speed increase is required, the PCM outputs the PWM signal to the
fluid port, providing the required fan speed increase. During the key on, engine running (KOER)
self-test, the PCM commands a 100% duty cycle. A DTC sets if the PCM detects the voltage on
the valve control circuit is not within the expected range or if the fan speed is less than a
calibrated value.

[stltikn]

When the engine is shut down it begins "heat soak" where all the engine parts tempratures begin to equalize. The cooler parts will warm up and the warmer parts will cool off. Natural thermo siphon of the coolant begins, the radiator warms and the clutch fan engages due to the increase in temperature surrounding it. When the engine is restarted the clutch fan will remain engaged until the incoming air cools it sufficiently. Note: If you remove your clutch fan for maintenance/etc. store it vertically, never lay it horizontally. The silicone fluid can leak out and you'll be replacing an otherwise good fan clutch.

[jesilvas]

Oh well that's cool.
And yes, the cool parts heat up and vice versa, but overnight, all the parts cool off and get very close to ambient temp. And, just like in a 7.3, the fluid in the clutch is thick from cooling below "cool engine temps" and from sitting all night.