Engine whistles when cold

This has happened twice in two weeks. When the temp is well below 0 I get a whistle from the engine that seems to be throttle related. Only does it at low rpm and low speed and only when pushing on the throttle not at idle.
Is this a vacuum leak or throttle body gasket leak? Going to vacuum test it tonight just wondering if someone has had this issue before

Do the whistles go Woooo?!

Seriously, I've never heard of this before. Definitely would expect a leak of some sort.

Ratpatator said:

This has happened twice in two weeks. When the temp is well below 0 I get a whistle from the engine that seems to be throttle related. Only does it at low rpm and low speed and only when pushing on the throttle not at idle.
Is this a vacuum leak or throttle body gasket leak? Going to vacuum test it tonight just wondering if someone has had this issue before

Click to expand...

I use to have that on my 2004 and 2011 F150. Could never find it and only happened when -10 or colder. I think it's just the truck saying is too F-in cold.

Yea it's a mid to low pitch whistle. Lower than your average whistle but higher than when you blow across the top of a beer bottle haha. I know maybe not the best description actually kinda hard to describe a whistle...

Haha I agree it's too damn cold!

I'm assuming a vacuum leak didn't get to check it yet.

I know exactly what that sounds like. My 04 5.4 f150 FX4 that I bought new, started making that sound around 2012 I think, but only when the temp. was zero or below, and still to this day I don't know where it's coming from. Truck still runs great 135,000 miles. the ( whistle ) would go away after she warmed up. BTW I agree, the noise is best described as a whistle.

Oddly enough, mine does the same thing, but it does it at any temperature.
Slight load on the engine, at maybe 20-25% throttle. I can easily make it go away by giving it more throttle or less throttle, but will instantly come back when I return to that 20-25% region.

I just toss mine up to harmonics due to the CAI. I know on my ST, once I put a CAI on it, a lot more engine noises were prevalent including general induction noises and the turbo BPV.

Are you sure you aren't hearing a whine rather than whistle?? All of us experience the cold whine... that is the power steering. Check that fluid level... i bet it's low.

4 sure it's not the power steering whine, I know what that sounds like, this is night and day difference. I too can make the noise go away by letting off the gas, or giving it more. Thanks for the advice. I always thought it was a vacuum leak but I'll probably never know.

Sasquatch77 said:

Are you sure you aren't hearing a whine rather than whistle?? All of us experience the cold whine... that is the power steering. Check that fluid level... i bet it's low.

Click to expand...

No it definitely not power steering whine. Definitely a whistle.

anyone still having this issue? Im having this slight whistle at low throttle under acceleration