midwestern

That's been the challenge with diagnosing the problem from day 1. It comes and goes so sporadically that it's hard to tell the effectiveness of any given measure. During the drive in today it was fine. More days than not it's quiet as a sewing machine. If it were related to an idler bearing I would expect it to get worse and worse ... not go away for days at a time, return for a short duration, and then improve right away. That sort of behavior does seem more fitting of a vacuum leak like you have suggested.

In any event there has been no change in fuel economy, no stalling or rough idle ... nothing to suggest a more serious problem. It's just kind of annoying when it happens. I'll have more time to look into it this weekend and will post more information when I have something substantial to report.

steve392

Heres a quick video of the whistling my truck is making. You need to have volume up.

midwestern

Steve,

I can't speculate what is causing that sound but I don't think our issues are related. It's hard to judge from the video but it doesn't sound all that loud. Hopefully it's just air box noise or a minor vacuum leaks somewhere.

For those interested, I have a little update regarding my situation. I didn't have any issues with the noise for the last week and was beginning to hope that the problem had solved itself, but it was not to be. It started to come back again this morning. During my lunch break I pulled off on a side street and wetted the belts with a cup of water I grabbed before leaving work. Doing this seemed to aggravate the noise substantially. While the ultimate resolution is yet to come I'm leaning strongly to suspect this is an issue with the belts and belt tension. In effect, when it's cold the belt has less traction and when it's wet it has a lot less traction. I don't have a belt tension gauge so I might need to make a trip to the shop to get it checked. I'll follow up when I know for sure if that's the issue.

steve392

I dont think ours are related at all either. The sound is not super loud but the video makes it seem quiet. The electric fan was drowning it out. I am starting to speculate that it might be the alternator making the noise. I am going to check the airbox in bit before work to make sure everything is snug and nothing is blocking the airfilter.

midwestern

Does anybody know how to release this style of belt tensioner?



The upper tensioner is pretty straight forward because it has a recess for a half inch drive, but I haven't had to remove this style before. Do you just put a breaker on the hex nut to release it or is there some kind of special tool?

I have a friend who works as a Mazda tech and I had him listen to the sound. He agreed that it was probably a belt issue and suggested replacing the tensioner. Apparently he's witnessed CX-9s which also have a ford motor develop similar symptoms. He said it isn't very common, but happens from time to time. I figure that if I'm going to have the belts off to inspect everything else I may as well reach for the low hanging fruit.

midwestern

Just figured I would post a quick follow up. I wanted to wait a week just to make sure I had truly beaten the noise but it appears to be gone. I wasn't able to pinpoint the exact cause; however, it must have been related to the tensioners or belt because replacing them eliminated the sound. To be fair the sound persisted briefly but I think it was due to the belts wearing in.

The job wasn't difficult IMO. It only took a couple of hours at most and I wasn't in a hurry. For those who may wish to know:

1.) The upper belt is trapped against the block by the tensioner so you need to be careful to examine the orientation before you take it off and replace it.

2.) The coolant hose makes removing the upper tensioner somewhat difficult. I found it best to remove the air dam and approach from below. I recall using an extension and applying some pressure to the hose but there might be other ways to go about it. You'll need a good assortment of ratchets and extensions. In general the belt access is better from below than above.

3.) Replacing the upper belt requires removal of the lower tensioner because there isn't enough clearance between the lower tensioner and the drive pulley to slip it in. If you're doing both the belts leave the lower tensioner off until you've installed the upper belt. Don't attempt to do one belt and tensioner at a time.

4.) My truck has 43K miles, 13 model year. The tensioner bolts were easy to remove.

5.) To release the lower tensioner the hex bolt on the pulley is a suitable anchor.

This was my experience. Your results may vary.

MarylandWildcat

Were you able to determine the cause? I seem to be experiencing the same noise as in your video.

midwestern

I should have known better than to suggest I had fixed the problem ... because the noise is coming back. Just a friendly psa for those who might come across the thread although I am at odds to expect this is a widespread issue.

What I can say as fact:
-The noise began w/ ~42K on the clock with the onset of cold weather
-Occurs while free revving the engine (P/N) or while driving
-Favors specific RPM 1500-1800, again at ~2400
-The noise is intermittent, only occurring on certain days
-The noise is aggravated by cold wet weather
-Wetting the belts intentionally aggravated the noise
-Replacing belts and tensions eliminated the noise for about a month
-The noise is coming back, but with less frequency and not as severe.
-Visual inspection of the newly installed belts does not reveal any wear.
-There are no leaks (water pump)
-There have been no changes to fuel economy, power ... etc.


While I had the belts off I checked all of the pulleys and didn't find anything suspicious. The only thing that seemed a little bit off was the water pump pulley which seemed to have a very small amount of play. That's the next thing I will probably replace if I decide to try shooting it another time with the parts gun. I'm not sure what else to try at this point.

midwestern

Just a little follow up because I think that I've finally reached the bottom of this ... or I should say the Ford dealership did. I stopped by to get a new drain plug from the parts department last weekend and ended up talking to an adviser for a few minutes. During our conversation I learned that I still have certified pre-owned warranty coverage. Not sure how I missed that? In any event, I agreed to let them have a look.

Their diagnosis revealed two issues:

1.) As I had sort of anticipated the water pump was malfunctioning. The mechanic determined that it sounded irregular with a stethoscope and it was replaced under warranty.

2.) The now infamous "T-connector" was starting to leak. I didn't notice any change in my coolant level or spillage so it must not have been leaking very badly. They informed me that it was dripping coolant on the belt intermittently and that may have contributed to the periodic whine. I didn't get this one under warranty, which is a bit odd given that they were willing to cover the water pump itself.