I have noticed on cold mornings 25°F and lower I get a whining/horn like noise from the engine as SOON AS I CRANK IT that lasts anywhere from 2 seconds up to a minute and then tapers off and stops. If you turn the truck off and back on the noise DOES NOT happen.

I swear it sounds like it is coming from the factory air intake tube.

I am baffled, I took it to the dealer and the service guy I was working with said he noticed his doing the same thing on cold mornings. We both have 07 5.4L trucks.

On mine, the only thing I have done to the engine is add just a K&N filter. yes, just the filter!

Next time it gets cold enough I will record the sound and post it on here and see if anyone has any ideas.

If anyone has any ideas...let me know! THANKS!

 

MY guess is it's the alternator. They will make noises when cold and the battery voltage is down. You probably had a good one on your original engine. Since the alternator sits right below the inlet tube, it can sound like that's the source. Next time you hear the noise, turn on as much electrical as possible, defroster, heated seats, lights on high beam and slowly rev the engine, if it gets worse under load, it's the alternator. Another test is to turn the steering wheel and see if the pitch changes, if it does, than it's power steering. Unfortunately, a little noise on cold starts that goes away once the fluid temps come up is acceptable from a dealer standpoi

 

I took this this morning. It was 24 degrees. The noise seemed to subside after turning the steering wheel. The video is about 2 minutes long and You can hear the noise great!!

Please watch and let me know if you have any new ideas!

The file is relatively large (~50MB).

http://www.trinityccenter.org/F150/f150noise.AVI

 

My '07 did that when it was -10F. A friend owns a fleet of 6 '05-'06's that tend to do it in the 20's or lower like your does and have done it since nearly new.

I'm guessing it's the power steering pump all po'd about the cold fluid, about like your clue about turning the wheel would indicate.

 

i was driveing my 05 f150 5.4 today and it made the same noise you guys are talking about ..and it 5F. but i think i may have a pump issue

 

My 2006 Navigator does the same thing. Did anybody ever find out what it is so if I have to explain to the dealership what sound it is I can?

Dave

 

They replaced the idler pulley on my engine. The noise has not been there since even in very cold temps.

Jeremi

 

I noticed my truck (06,4.6L) the power steering pump will make noise in really coldweather, 0F or below. Last's about 10 second's.

Karl

 

I'd whine too if it was that cold.

 

that sound is the power steering pump cavitating.

 

If it really bugs you, you can get synthetic power steering fluid, which will knock down the sound at that temp. I had an 97 Expedition that made the same sounds and once I switched over to all synthetics most of those noises went away at cold temps.

Now if I could only pre-heat the seat so it would not be hard as a brick at -10!

- Joe