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Discussion Starter #1
Hello
I have a 2001 F350 7.3L Turbo
I have 131,118 miles
Truck is stock
Recently I have replaced ....
upper and lower ball joints both sides
both batteries
alternator
fuel filter
oil and oil filter
idle validation sensor/gas pedal assembly

this took care of my problems up until today
I noticed a weird sound when driving and specifically only hear it above 25 mph and below 45mph
I have put the vehicle into neutral when going say 35mph and the noise is still there ... the noise is a howling sound ... not super loud but loud enough that its alarming

I dont have this problem when i start my truck and simply let it idle

i have checked my oil - its fine as well as all other coolant levels
i recently have greased the whole front end and added rear end grease
the brakes are fine as well

The only thing i thought of was the HPOP which last time i had a scanner on the truck no codes came up (i dont have a scanner and had to have a local shop scan it for me)
also im not sure if it would be a water pump issue

Something I'm not sure if it is related but on the air compressor - is it normal for the plate on the outside to engage then disengage then re-engage and disengage (and so forth) and everytime it either engages or disengages there is a clicking noise that i assume tells it to engage

im not sure how that would relate to the noise im hearing


this is my first diesel so im on a learning curve but i love my powerstroke:ford:
Thanks
 

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Discussion Starter #2
also the problem happens randomly - there was nothing on the way to work - then when i was going to a different location for work i heard it alot and thats when i also put it in neutral and still heard it when i was coasting at like 35mph
then i just made two more trips around town and nothing
 

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Discussion Starter #3
i also found out why the plate is engaging and disengaging on the compressor so thats solved - i learned something new about that - but no idea on the metallic howling sound
 

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Check the diff fluid, carrier bearing and wheel hubs.
 

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Does the noise change if you go into neutral and manuver the truck side to side? If some variation, likely wheel hubs IMHO, the torque of turning will cause the pitch of the sound to change. If stays constant, could be propeller shaft bearing ,or rear end issue.

Good Luck

Coolhand
 

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So the sound is not RPM dependant since when you put it in neutral while driving, you still get it.

And you don't get it when you're idling, so basically the truck has to be moving and the sound is still present even at idle RPMs while moving.

Axle/bearing/front end problem?

Does it come and go if you steer right or left?
 

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Before I read any replies, I too am thinking differential. It will sound differently at different temperatures. The sound changes as you accelerate/cruise and coast?

Can you upload a video of the noise?

Sent from my DROID RAZR using AutoGuide.com App
 

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Discussion Starter #8
thanks for the responses - the first problem referencing to rammertide07 is its hard to know when it will happen - this has just happen over the last 4 days
it happened on one trip through town 4 days ago then nothing for two days then it happened yesterday for one trip through town but nothing else the whole day then today it happened on one trip to and from a location but i drove around doing other errands after that today and nothing - so its hard to replicate and i doubt the video on my phone could pick it up over the sound of my engine (quality of sound recording on my phone)

reefblue - yeah its not RPM dependent since it made no difference in the sound when going to and from drive to neutral - i did notice the sound becoming quieter (whenever it would act up) as i slowed down so say at 40mph you could actually hear it decently well but by 20mph it was very faint and the sound seems to be coming from the front - since i have a 12 or 14ft flatbed i would doubt i could hear a rear end issue and i have noticed then whenever i actually hear the metallic howling if i lean forward i can hear it a little more thus i feel its front end ... i havent tried to get a difference in the sound by steering from left to right but tomorrow when i go around town ill try that if the problem replicates itself tomorrow

coolhand - as highlighted up there the sound becomes quieter as i slow down and havent tried side to side movement yet

i gotta do errands in the morning then ill provide an update - if i have time i might try to pull the passengers side wheel off and look at the wheel bearing because i feel as if its coming from that side

thanks again - ill follow up
 

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Sounds like exactly what I'm experiencing. I just put the axle on jack stands and run it up to 50mph on the spot. Same noise so it's not my front end. Gotta be trans/transfer case/driveshaft/differential/bearings. Doh.
 

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Change the drive shaft u-joints. There's no real good way to check them unless you pull them a part... Mark all parts before removing and putting back together or you may have a balance issue...
 

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I found out my noise is 2 piece driveshaft carrier bearing. It's definitely not spinning smooth. Just have to buy a big socket to get the nut off the yolk so I can replace it.

You could also remove the rear driveshaft and go to 4wd high, use it like a front wheel drive car. Just go easy on the throttle. If noise disappears it's the driveshaft u-joints or carrier bearing. With the carrier bearing you can't usually tell if it's bad by wiggling the shaft around. To check easily, remove the two carrier bearing retainer bolts. Drop shaft down a bit, enough so you can spin the whole carrier bearing retainer around the shaft. You'll soon discover if it spins easily or is noisy/rough.
 

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I took my driveshaft, with new center bearing in hand and went to a local machine shop. Picked up the completed shaft a couple of hours later, installed it, took truck for a test ride - NO more weird noises!!!

I am happy.

Butchcassidy1
 

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My recommendation is to find a nice empty stretch of road and put it in neutral and shut off the engine. That should eliminate the possibility if anything engine related. But from the sound of it, I'd say drive line related. I had a similar issue with my wife's car and it would only make the sound under load, so when I put it in jack stands and ran up the speed nothing happened. Turned out to be the carrier bearing was shot. Good luck.

Sent from my Galaxy Nexus using AutoGuide.Com Free App
 

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Truck goes into the shop tomorrow. If it was summer, I'd chase down the problem myself. But you won't find me crawling beneath my truck in -20 weather if I can help it. I'll report the results.
 

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It was a U joint

Took the truck in to the mechanic yesterday. They first thought that it was going to be a bad carrier bearing, but it ended up being a bad U joint (furthest one back). They replaced the U joint and now it rides smooth as silk (for a pickup) and no more vibration.
 
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