I searched and read all about the piston slap, cam phaser noise, valve clicking and some other various problems on a cold start. I believe what I am experiencing is different.
For the last few months on a cold start I sometimes notice a loud buzzing noise. It's definately coming from the engine. It's sounds like a really loud fuel pump. But my fuel pump is not up front so that isn't it. It doesn't get lounder or faster with RPMs and it doesn't go away by putting it in P, N or any other gear. It also doesn't go away when heater/AC is off. It will go away in about 5 minutes or so though. The truck runs fine so I am not that worried about it. I am just curious as to what it is.

 

My guess would be a heat shield on the exhaust, probably the ones right under the cab by the tranny. Or possibly a bracket or something under the hood is rattling until it warms up and stops. Have you tried locating the noise with the hood up while its doing it? Hope you solve the mystery.

 

last couple days it has been -25F in the morning i get the same buzz you are getting, but for shorter duration- about a minute, if i dont give it any gas, but if I rev it a couple times, only about 10-15 seconds

 

It really sounds like it's coming from the engine. The problem is I don't hear it until I get about a mile down the road and by the time I get to where I am going it stops. I haven't gotten out to inspect the noise yet because it's usually 6 in the morning and dark.

 

If you let the truck warm up for a few minutes and then try to hold the throttle right about the startup rpms, does it still occur? I'd think if it was a heat shield it would always rattle around that range. Just a guess.

 

I know when I started mine up this week (-8 degrees) it sounded like I was killing a rabbit. That went away quickly. I did notice a 'buzzing' sound, but it goes away while my truck warms up in the driveway. Just cold messing with things.

 

Is that the technical reason? Maybe there is a TSB
I'll try and pinpoint where it is coming from this weekend. It doesn't seem to make the noise if I let the truck warm up and then head out.

 

I have had some noises like this. I think when its very cold out..

I have found that it was the power stearing pump.. turn your wheels when u start it up... see if you notice the noise change in sound at all.. if so u might wanna see if the power stearing pump is full...

 

when my truck sits a few days in the cold...and start her up...sometimes sounds like a cat being chewed up by the fan..best way I can describe it..rofl..no kidding

 

Same here. Last week it was in the single digits for our daily highs and the range was around -5 to 7 F. For those couple of days, I too had the winding noise. Sounded like an electric motor winding out of control. Or, as some people put it, the fan eating a small animal. Lasted about 5 seconds on start-up and then it was gone.

 

Ya...so what is it?????

 

I have the same noise, too, its been around 15 every day for the last 2weeks, and I hear the same noise when I start mine up cold. I suspect that it is the thermostatic clutch fan. My brother had a '95 f150 that had the same noise, and it kept getting louder and louder until he replace the clutch on the fan and then it went away (the truck was probably 5 years old with about 50K on it when he replaced it). I think the reason it goes away when it warms up is because the clutch starts to warm up and engage the fan, thus the noise goes away.

 

Who knows. The sound I am hearing doesn't sound like a small animal being chewed up by a fan though. Also it doesn't get very cold here compared to some of the places you other guys live. 26-28 degrees is probably as cold as I will ever see in seattle.

 

Ford tech told me that it was the power steering pump. When the fluid is really cold, it does not behave as it should. He said when the pump starts pulling fluid it creates alot of small air bubbles which make the pump sound "like a low cat meow" (his words). I had heard it twice last week when the temps were around -10. Don't know, but he said if anything does not sound right, bring it in.

 

i read this post the other day, the next morning, i noticed a "buzzing" noise. i have about 2500 on mine, this is the first time i noticed it. however, that was the first time that i did not let my truck warm up for a few minutes befor leaving. having just read about this the night befor, i took a min. to try and locate. while it sounded like it was under the hood, mine was comming from the windshild, dash, and d side a pillar area. i wedged my finger tips ovet the vin tag, pressed down on the dash with the heal of my hand, and braced my fore arm against the a pillar, and the noise went away.