Engine whistles when cold

If you are into snake oil treatments, haha, this power steering enhancer made by Keyser is supposedly good at quieting Ford power steering systems. I ordered a jug off Amazon to give it a try. I get the loud whine after starting in cold weather, but it goes away after several minutes.

https://pro-blend.com/products/power-steering-enhancer-12-oz?variant=1185670040

After BG power steering flush, making sure all air out of system, and using power steering enhancer, still had noise/whine at cold start. Turns out it was worn out idler pulley and tensioner, had those replaced along with new serpentine belt, no more noise! Here is blurb from service manual.

A couple weeks ago and for a day or two it got to be nearly 0 degrees here in NY and I heard my truck do this for the first time. I haven't heard it since and I'm not worried about it.

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

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I found these whistle related symptoms in the service manual for what they are worth...

I've been waiting to post it to make sure it wasn't a coincidence but I had had some issues with the vacume lines going to the hubs for four wheel drive. I fixed I with the info from another post on here,

Weak Vacuum Line and grinding noise FIX.

I haven't had this whistle since but it hasn't been super cold here for a while but I am starting to think that was the issue. Hope this helps anyone else with this problem.

update my noise is fixed. My idler pulleys and tensioner pulleys were bad.

siooss said:

After BG power steering flush, making sure all air out of system, and using power steering enhancer, still had noise/whine at cold start. Turns out it was worn out idler pulley and tensioner, had those replaced along with new serpentine belt, no more noise! Here is blurb from service manual.
View attachment 96466

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I've had a whine going on this winter when starting cold. I planned on replacing my serp. belt anyway, guess I'll do the pulleys too.

I'm thinking I'll do both puleys and the idlers shown below (#2 and #4)



Anyone know which ones were replaced to fix? Also, did you replace them yourself or have ford do it?

Left Hand pulley was replaced, by dealer.

siooss said:

Left Hand pulley was replaced, by dealer.

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#4?

Also did they replace the whole tensioner/arm pully. It looks like you can only order those as an assy..