08 6.4L Cooling fan coming on at high speeds

[AudiS400hp]

I have an 08 f450. while driving, the cooling fans will randomly come on even doin 50mph or higher. they will shut off once the truck shifts. just replaced both thermostats few days ago and problem still consists. Any suggestions?

[bentstroke_02]

is your ac on? How hot is it out?

[AudiS400hp]

Originally Posted by bentstroke_02

is your ac on? How hot is it out?

Tried with AC on and off. Its been around 90 a few days but mostly 65-90 past few weeks. but why would fan come on even goin 55-70

[Johnsabine2003]

Mine comes in about 1200 rpm and quits about 1800 rpm. That sounds like what you're describing. I just figured it was normal.


Typed with my thumbs from my Autoguide app.

[srjd]

does the ac make a difference?? just wondering

[AudiS400hp]

Originally Posted by srjd

does the ac make a difference?? just wondering

Nope. does the same thing with the ac on

[Eric@PTP]

Have you checked your coolant level ? This happened to me once and it was due to a leaky upper radiator hose o-ring. Coolant level went down far enough to get just hot enough to kick the fan on while driving. It how ever didn't register on the dummy gauge on the dash that it was getting hot.

[cp2146]

All the previous suggestions are good ideas and definitely worth checking, but according to the book, for hot weather it is normal. Read below. This is a direct quote from the owner's manual.

Your vehicle is equipped with an engine driven cooling fan drive (also
called a fan clutch). This fan drive changes the fan speed to match the
vehicle’s changing cooling air flow requirements. Fan speed, fan noise
level and fuel consumption all will increase based on the driving
conditions that include trailer towing, hill climbing, heavy loads, high
speed and high ambient temperature, individually or in combination. The
fan drive is designed to provide the minimum fan speed (and resulting
fan noise and fuel consumption) required to meet the ever changing
vehicle cooling air flow requirements. You will hear the amount of fan
noise increasing and decreasing as the engine power requirements and
vehicle driving conditions change as you drive. This is to be expected as
being normal to the operation of your vehicle. High levels of fan noise
might also be heard when your engine is first started, and should
normally decrease after driving for a short time.

Now if the fan spools up and stays up, then you might have a problem with the fan clutch. But it sounds like that isn't your problem. Since yours is coming on at odd times, it might very well be a coolant level issue. Mine cycles too, but only when it's really hot outside (mid to upper 90's) and only when I've been idling for a couple of minutes at a stop light or in stop and go rush hour traffic. It always goes away after a few seconds.

[the-last-international]

Originally Posted by cp2146

All the previous suggestions are good ideas and definitely worth checking, but according to the book, for hot weather it is normal. Read below. This is a direct quote from the owner's manual.

Your vehicle is equipped with an engine driven cooling fan drive (also
called a fan clutch). This fan drive changes the fan speed to match the
vehicle’s changing cooling air flow requirements. Fan speed, fan noise
level and fuel consumption all will increase based on the driving
conditions that include trailer towing, hill climbing, heavy loads, high
speed and high ambient temperature, individually or in combination. The
fan drive is designed to provide the minimum fan speed (and resulting
fan noise and fuel consumption) required to meet the ever changing
vehicle cooling air flow requirements. You will hear the amount of fan
noise increasing and decreasing as the engine power requirements and
vehicle driving conditions change as you drive. This is to be expected as
being normal to the operation of your vehicle. High levels of fan noise
might also be heard when your engine is first started, and should
normally decrease after driving for a short time.

Now if the fan spools up and stays up, then you might have a problem with the fan clutch. But it sounds like that isn't your problem. Since yours is coming on at odd times, it might very well be a coolant level issue. Mine cycles too, but only when it's really hot outside (mid to upper 90's) and only when I've been idling for a couple of minutes at a stop light or in stop and go rush hour traffic. It always goes away after a few seconds.

This is good info. I agree