I posted earlier about a whistle that appeared when I was towing my old travel trailer (6000 pounds). It only happened a couple of times, and I had a hard time replicating it, so I elected not to waste any money with the deductable, and possible additional costs for a non-covered issue at the stealership.
Now, I am towing a larger 5th wheel trailer (11000 pounds), and am experiencing this whistle on every steep grade, while towing. Below are a couple of things I noticed, that had to be, before I would get the whistle:

* It only seems to happen while the cooling fan is engaged, and also only when the rpms reached 2800 and above.

*If the fan was on, but the rpms were turning below 2800 rpms, then it would not whistle. It would, however, after the transmission downshifts, bringing the rpms back up, while climbing.

*If the engine was spinning at 2800 rpms, and the engine fan was not engaged, then it would not whistle, until the fan would kick in.

* It only seems to occur when I am climbing a steep grade, on a warm day. Although, I haven't experimented on steep grades on a cold day...

It sounds to me like there is an issue with the engine fan system, but I thought I would put it out there, just in case any of the diesel guru's out there might know of something else that would cause a whistle like this, i.e., turbo?

Oh by the way, I also think that I have a performance reduction lately. However, I can't know for sure, as I have never towed this much weight with my truck before. I just kind of expected that I would be able to pull to the top of these grades, with a little extra peddle to spare. I have to floor it, just to "try" and keep up with traffic. And I haven't calculated my fuel mileage while towing this beast yet, but WOW, that fuel gauge needle sure does drop like a rock!

 

could the belt be slipping as the clutch fan locks up more?

 

There was recent thread on this very topic, and BowTieHtr (he is tech btw) said that he has seen this problem before, and it is usually a small crack in the right side exhaust up-pipe adjacent to the Y in the pipe at the EGR cooler feed. The crack is small and under heavy load and certain RPM ranges the exhaust gasses are escaping at the crack causing a whistling sound. This will also cause a reduction in power as there is now less exhaust going throught the turbine side of the turbo to power it.

Check the up-pipe very carefully for a small crack. You may have to remove the pipe to do this, which would mean you would have to take the turbo loose as well.

Here is the link to the previous thread.

Good luck

 

Balckhat,
I am not able to see the link in your post. I'll do a search. This sounds like it could be the problem as it really does sound more like an air whistle than a belt. I think I would notice what a belt sounds like. This is very much more a whistle sound, than a squeal. Thanks mucho guys, for the info...
Tim

 

Hmm here is the link it didn't copy the first time
http://www.ford-trucks.com/forums/61...ideo-link.html

 

Hey, OLFORD did you ever have your exhaust manifold off at all? If in fact the up pipe is cracked on my truck, Im obviously wondering why? I did take off the drivers side manifold to tap for an EGT sensor. Other than that Im not sure how or why it would have cracked other than it just did...My scenario is very similar to yours, but I don't necessarily notice a loss of power.....if I have a loss, it isn't noticeable to me in that towing scenario.
I am taking my truck in this week for a possible replacement turbo. The exhaust side oil seal in turbo is suspected of leaking and puffing white/gray smoke. Crazy they have to replace the entire turbo to swap the seal.....While they have the turbo off I am going to insist that they check the integrity of the EGR uppipe. I'll let you all know what happens ~Brad

 

badbrad60,

The up-pipe does not have to be removed to crack. It can occur do to the high heat cycling and the y-branch at the EGR cooler connection. There is alot of heat, stress and load on the up-pipe in this area.

Hope this helps

 

Went on another trip pulling the Trailer. I have since had a new turbo installed. The whistle is still there. I noticed that if the engine fan was fully engaged (roaring) then the whistle would go away. this was all around the 2800rpm range. I was playing with the A/C button, and when I turned the A/C on, the fan engaged, and the sound in fact went away. I turned the A/C off the engine fan reduced noise and the whistle came back. The dealer said they check the up-pipe when they changed the turbo, but who knows...If it is not the up-pipe, the maybe the belt or fan clutch...?

 

2005 stock, no mods besides lift and tires, but even before that, always heard that high pitched shrill pulling my trailer up a hill, if anyone ever figures this out please post, thanks, it sounds exactly like that video post up cuesta grade in the other related thread

 

Okay, a new development.
I just returned from a trip, towing my 11K 5th wheel, to Oregon. Ascending quite a few steep grades, I had that pesky whistle annoying me on my trip. On a particular grade, on Interstate 5, in Southern Oregon, the whistle got real loud. I turned my stereo down and opened my window to see if the sound was as loud as I suspected, and it was screamin'!
Then, all of the sudden, it just quit. It did not do it again for the rest of the journey. Go figure???
Anyway, I thought I should probably post this, as it may be something of interest. Maybe some of our Club FTE member "techs" can shed a little light on this one. Come on guys, share that weath of knowledge with us. I know you guys can figure it out.

I'm just glad the whistle stopped.

 

I m new to the forum but sure am happy to see the postings on "whistle under the hood".

I have the same problem and the Ford dealer over the past year has replaced the fan clutch twice, belt, fan shroud (both sides) and fan. Just last week I towed my trailer 7500Lbs up a grade in 85 degree heat and the whistle returned again.
I once again am going to the dealer. Hope maybe these postings can shed some light on the problem.

Love the 2005 F250 but want that sound to stop as it could possibly lead to a bigger problem.

 

I have had a loud fan noise also, the fan kicks in for 5-8 seconds then shuts off, this when I'm towing in high heat, on a steep grade, 10K tailer, high RPMs. But I hear a soft high pitch whistle when the fan is on. I hate going to my dealer, they seem more lost than me.
Someone once said there is another fan for fuel return ? is this true?

 

Im still VERY curious as what the heck is making this noise...mine has been whistling since new...12k on it now and it still sounds like the Andy Griffith show I got $100 for the one who nails it...someone that has had the problem and actually fixed it.....Come on guys...lets solve this stupid whistle...

 

Well, my whistle has stopped badbrad. Does that entitle me to a hunerred buks? Ha, just kidding. I know it's not that funny, but ya gotta have a sense of humor, even when annoyed, or you tend to age a little faster if you let it all get to ya.

I'll get after my local Ford Diesel Tech about that damned whistle. You never know, maybe he'll have some ideas. And Brad, regarding the hunnured bucks, don't sweat it. That's what this site is all about, to help eachother out. Don't cost ya a dime. That's why we are supporters eh???

If I get any info, I'll certainly share. I just wish the dealership would have found what was causing the whistle before it suddenly stopped on it's own. A diagnosis would have been educational for all of us. Kind of frustrating, when you are left with that void of info, and wondering WTF. At least I can say, from experience, that it doesn't seem to cause any damage to anything. Just an annoying whistle, until whatever it is gets unstuck, apparently.

Best Regards all, Tim

 

"ya gotta have a sense of humor, even when annoyed, or you tend to age a little faster if you let it all get to ya."

Amen!!!!

Thanks Tim for keeping a ear out for the whiiiiiistle..

Folks like you make FTE Rock ~ Brad