Can anyone name this noise?

[robert smith]

Coming back from camping this weekend I heard a noise which I can best describe as a muffler/exhaust -just- starting to go bad ( everything seems tight underneath) only over 50mph?
U joints, tranny???-its an '07 E450, just around 24k miles.

[HunterJ]

How does a muffler or exhuast go bad? Does it sound like leaking air?

[WEWILLE]

Does it sound like an engine noise? Or a rattle, squeek? How about vibrations? Does it sound like frontf, rear, left or right? As much info as possible would be great!

[robert smith]

Its tough to describe, imagine someone driving next to you, again at highway speeds, with a loud muffler. Not a whine, no rattles, no vibrations, just a very audible low frequency noise. In fact the first time I heard it I spent about 15 seconds 'looking' for another vehicle in my blind spot.
Perhaps if you imagine what a Harley with stock pipes would sound like riding along side of you on the highway.

Tires look perfect, pressures are what they are supposed to be, weights haven't moved or spun off. Trans fluid is good, exhaust system looks tight.
Just started.

[WEWILLE]

What kind of tires do you have? Does the noise change with throttle or load changes? Could be u-joints in rear driveshaft. Check your diff and transfer case fluids. Look for some soot on the firewall. The uppipes tend to crack.

[Jake]

It could just be the exhaust from your own truck.

[tootall]

i have an 04 f250, does the same thing, when it shifts into the final gear its at really low rpms and it kinda resonates inside the cab, took me a week to figure it out, then i drove with out the radio on and just like clock work everytime it shifted into that final gear had a low rumble, it quits round 53-55 mph....if its the same noise....i think it is

[robert smith]

Thanks all.

WeWillie/jake, stock tires, Michelin, very non agressive thread design. The frequency of the noise does not change, trans fluid is where it should be no soot or any sign its my exhaust. Dealer wasn't able to hear anything and also checked exhaust system along with drive shaft and joints.

tootall, I first noticed the noise this past weekend, after about 23k miles the same for you.

hunter, not an air noise in the sense of pitch, a drone like an exhaust or rumble.

Tech said all the noises he heard on the highway were normal so maybe I am imagining it or for some reason the noise never registered with me before.

Leaving for vacation thursday so I'll have a few thousand miles to check things out again-especially the 10-30 Amsoil oil I just dumped in; I'm taking about six quarts along just in case....

My thinking was the transmission which is why I asked for an early fluid change and requested synthetic but the dealer said to keep the cash in my pocket..

[bismic]

Had a noise similar to your descriptions on my 7.3L after installing the aftermarket exhaust. It was a downpipe rub that occurred at certain rpm's.

When you get back from the trip, you will be close to the 30k interval on your tranny anyway. The Mercon SP is synthetic - no need to change types of fluid (in fact it could cause big problems if you do).

[Ryan Rønning]

Sounds to me like its just an exhaust noise. One thing I have noticed about us diesel drivers as a whole is that we "ALL" seem to over analyze everything! LOL