Chirping noise

Yes, my mechanic did check the AC and turned it on and turned it off as well as all the other climate control positions on the dial. When it is cold out either you cannot hear the sound all or just barely and as it gets warmer the sound gets louder. The sound also quickens as I accelerate and slows when I decelerate. After a two hour our drive it came back full force. I have owned this truck since it was made and it has been very well maintained and the engine runs very strong and actually the AC has been used very little. I normally just run anything on my climate control dial on vent and it does not kick in anything for the air compressor. I have had no problems with the serpentine belt making any noises until these three police were replaced. The spring loaded tensioner pulley when he replaced a second time did reduce the sound significantly but not anymore.

My mechanic has taken the belt off when it has been chirping and he has tested all of the pulleys and none of them have been making any noise and then when he puts the belt back on it still does not make any noise and it takes a few days for the noise to come back. I have had this truck out to the shop like eight times because once the belt is taken off the noise stops for a few days and then slowly comes back and then as it heats up it starts to get louder. To me it seems like something is out of alignment where after the belt is put back on it takes a few days and the bell moves to where maybe it is rubbing against something but he does not see any marks on the belt either.

Yes, this is the second belt that we put on. It is a different brand, top-of-the-line that they have just come out with, the inside of the belt is green in color. I just went out and started up the truck which is chirping very loudly now after this two hour drive and I sprayed some water on the belt right around the AC and power steering pumps and the noise immediately went away and then after a little bit started to come back.

Sorry but by the time you sent your reply my engine cooled down enough that the sound has gone away again. I did actually record an audio of the sound earlier on my phone but I can only send it by text or maybe an email.

Where this truck is located temperatures are at freezing right now and when the belt warms up it starts loudly chirping and when it cools down it stops. When the weather is warmer it will start chirping barely audible at start up. I do not know if belts expand when they warm up and maybe this tension-er does not work with my truck and possibly I need to get a Ford motor part for specifically my truck. Just a thought.

Thank you for all your input. The synchronizer I do not believe has been checked, I will have to double check on that with my mechanic. When I drove my truck this morning the sound was completely gone and the engine was quiet.
Just to recap, I had three pulleys changed because the bearings were bad and according to the diagram on the front of my truck it was the idler pulley and the tension-er pulley and then the other one which the name got rubbed off I believe is the spring loaded tension-er, and also the serpentine belt because the inside of it was chewed up, and also the alternator Replacing the pulleys and bearings fixed why I had originally brought the truck in but the very same day I picked the truck up, by the time I got home the serpentine belt started chirping which it has never done before. When I brought my truck back in, the mechanic took off the serpentine belt to see if there was any rubber on the pulleys and there was not so he put the belt back on and the noise was gone again. A few days later it started chirping again and I brought it back again and the same thing happened as my previous visit. I finally brought it back and left it with him for a day and they let the engine run until it started chirping again and decided to put a different new top of the line belt on it and that did reduce the chirping sound it was making, in fact it was quiet for about the first two weeks and then the chirping started coming back. I brought it back to the shop again and left it for another day and after about three hours of inspecting it my mechanic decided to change out a second time the spring loaded tension-er which improved it even more and the chirping was barely audible. After that he said he did not know what else to do to make it completely quiet again like it was before and I would just need to drive it until either the sound got louder again or something broke. Well after this two hour trip yesterday It did get really loud again and so I sprayed water on the inside of the belt and immediately the noise went away and slowly returned. According to an Internet site if you spray water on the chirping belt and the sound goes away and slowly returns, it is because of a misaligned pulley, and if you spray water on the belt and the sound gets louder then it is a slipping belt. From what I have learned a slipping belt would be because of the spring-loaded tension-er. To me this would say the chirping from the belt is directly related to having these three pulleys/bearings changed out. Something has to be misaligned that he has not seeing are those tension-er is not keeping it tight enough when it warms up. One of my other observations is that it seems to always take a few days before it starts to make sounds again after the belt has been removed and put back on which says to me it works itself into a position that makes it start chirping. Does not the water/spray bottle test prove that it is either a misaligned pulley or the spring loaded tension-er, and those were all changed out immediately before this chirping sound started.

Just left work and it was quiet and after about four miles it has started chirping again. I will be sending a video with the noise.

Sending a video, hope it comes through.

Yes, I addressed the tensioner with the spring being replaced in my second post. It has been replaced twice. And no, there is no continuation of chirping after the engine is turned off.

Hello, I addressed that also in an earlier post. When I sprayed the water on the belt over by the AC and water pump side of the belt the noise goes away completely and then slowly returns. From what I have learned that means there is a misalignment of a pulley. If the noise gets louder than the belt is slipping.

I do not know the different brands. It says on my paperwork that it is just a serpentine drive belt that was under warranty I believe it probably came from AutoZone or Napa and the second belt says K061031HD/premium heavy duty belt and that was the second belt that was put on. It is supposed be new on the market and the underside of the belt is green. And besides the alternator it says that the tensioner assembly and the smooth idler pulley and the grooved idler pulley were replaced.