My '08 Super Duty with the 6.4l diesel has 5000 miles on it. I have been very happy with the truck except for the gas mileage (10-12). While towing about 6000 lbs over the Colorado mountain passes the engine begins to howl like the wind. It sounds like wind blowing hard outside your home in a storm. It only happens when she's begining to work hard to make a grade, especially at high altitudes. Anyone else had this problem??

 

That would be the engine fan.

My F150 will make it sound like a freight train going through parking lots and sometimes down the road when the fan clutch kicks in and matches the engine rpm to the fan.

It's just the engine doing the right thing... that's all.

 

Something doesnt seem right...does it get 10-12 unloaded or pulling the trailer? Mine (F250 Crew Cab 4x4) is getting around 15mpg with a mix of city and open road driving. What gears do you have....mine has 3.73s. Maybe thats the difference.

 

It's your fan kicking in... Yes it's normal.

 

That is about right. The 6.4 is not known for good mileage. It takes a lot of fuel to make all that power. The 7.3 and 6.ohno got much better mileage than the 6.4.

 

Yup...more power needs more fuel. At least you don't have to put the pedal closer to the metal to 'git 'er done'!

Besides...beasts are meant to roar, right?

All joking aside...if you're concerned have a diagnostic done on it...I'm sure it's just nature of the 'beast'. Engines tend to work harder and get hotter at higher altitudes (lack of Oxygen)

 

Yeah 3.73 gears and 10-12 mpg whether I'm towing or just around town. I guess you guys could be right about the fan but WOW is it noisy!! Is it a clutch fan or electric?? Guess I should know. My '05 F-150 5.4l never made this sound, unless its got a different fan system. It truly sounds like a bigtime storm outside the window of your home.

 

I guess I should have clarified that mine is a 2008 with a 6.4 as well.

 

i have a screw with a 5.4l and my fan did the same thing. it's a clutch type fan. it was about 115 deg out side and i was running a/c. i didn't understand what the sound was at first cause my truck never did that before. but i guess since it was so hot outside that the clutch went to full engagement. and it was pretty loud even with the windows up.

 

He's also at high altitudes, which could lower MPG some as well and cause the engine to starve for air. It *might* be the turbo spooling up some as well, kind of hard to tell from a text-only description.

 

I thought altitude only effects NA engines....basicaly the turbo is pressurizing the cylinders takeing the slightly veriations in atmospheric pressure out of the equation. Certainly heat wil still effect it but I dont thing alltitude should have much of an effect.

 

Speaking of roaring... I was sitting at the drivethru at my local bank yesterday with temps around 75F, and I probably idled 10 minutes... maybe more... who knows, but when I came out of the bank, it was like a tornado going down the road for like 2 minutes.

I've never noticed it before... or payed attention to it until this thread...

 

as has been said, its your fan no big deal. BTW it is a manual clutch type fan

 

Interesting! I never knew that, cool

 

Shouldn't be... When I was up in the rockies I didn't notice any affect on my MPG... Except for when I woke up to my buddy doing 90...