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Ditchplains1

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Ok, here goes...90,500 miles....
Driving for about 40 miles at around 50-60 mph on two lane blacktop primary road when I caught up to a F 350 dually pulling a 28 foot camper travelling about 50 mph. We were both going up a slight but long slope. As I slowed just taking my foot off the gas pedal...
A high pitch whine increasing to very loud was heard. I put the tranny in neutral, and pulled to the side. No change with revving the engine in neutral. As I slowed the whine disappeared at about 40 mph. No pulling. Normal 15.3-15.8 mpg's on the trip...300+ miles. The whine recurred several times around the 50 mph speed on smooth roads. Interestingly when going downhill it was impossible to reproduce...either with throttle, brake, or coasting. No whine on rough roads...about 180 of the 300 mile trip. Only able to reproduce it on level or slight uphill grades. No whine with heavy throttle. No change in whine turning wheel left or right.
Thoughts? Recently replaced front IWE's...less than 5,000 miles ago. Recent belt tensioner/belt change, 2,000 miles ago. Rear axle bearings? Pinion? Transfer case? Other than the alarming whine no physical changes...no vibrations, normal steering, normal braking, normal acceleration, normal coasting...

Thanks in advance....
Eddie
 
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CoronaRaptor

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You need to video tape the noise for us bro! I wonder if it's the torque converter or one of the cooling fans?
 
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Ditchplains1

Ditchplains1

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Sage,
No change with increasing or decreasing rpm's. As I initially pulled to the side I revved the engine while in neutral to 3500 rpm's with no change. As I pulled over and the rpm's dropped to 1,000 or so the whine continued until it dropped below about 40 mph...
Worse still I couldn't tell if it was coming from the front or rear...
Eddie
 

AndysLog

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we would just play the guessing game all day. you need to recreate with a video.


the best thing you can do now since it sounds you are not mechanically stupid, check over everything that moves and can potentially make that noise.
 

Ruger

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I think @phydough has it right. At 90,500 miles your U-joints would be at the end of their lives. The fact that it doesn't happen at heavy throttle or on downhill grades is revealing. I'd change out the U-joints just on general principles because of the mileage.
 
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Ditchplains1

Ditchplains1

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Update...
Took it to my local repair shop, put it up on a lift. Nothing! Rotors not scored, U-joints tight, No slop in drive line. No play in wheel bearings, no metal on metal sounds. No leaking fluids. Drove it with mechanic and could not tell where the whine was coming from. Postulated it was possible wind whistle...but the initial whine became very loud as I slowed down. At present it continues to come an go, but only between 40 to 55 mph. Very high pitch; and easy to miss if not listening for it. No vibrations. Truck tracks like on rails. Normal MPG's. While driving with mechanic and whine was present, put it in neutral and allowed revs to drop to 1000 with no change; none with revving engine. One change today was that it now comes on with going downhill as well as uphill, and remains for a longer period of time...15-30 seconds then disappears. Disappears with any acceleration; but with steady pedal pressure will now last 15-30 seconds.
ATF level , Oil, PS fluid all good. Transmission temp 197.
I don't think it is the engine fan as the temps were in the 50's and luckily my truck tends to run cool. The fan rarely engages, and it was foggy and later raining when the whine initiated. The last time my fan kicked on was while hooning in the sand a year ago; never kicked on towing a boxy 2,000 pound trailer in over 4,000 miles.... and yesterday I was following a trailer for 20 or more miles at about 50-55 mph, 5-6 car lengths behind, up a gradual incline on smooth road in foggy 50 degree weather.
Most recent mod was the 27 fuse change to slot 70 with upgraded 20 amp fuse.
The guys at the shop are not sure either; it'll have to worsen before they can find the source....And DD IV next week!
Thanks for all of your thoughts....
Eddie
 
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phydough

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I think @Ruger has it right. .:biggrin:

U-joints can be tight and still be bad. They can still be tight AND DRY as a bone, just grinding away little slivers of steel. I am positive your mechanic didn't grease them while he was under there, as there are no zerks with the stockers. They are cheap and easy to replace, very worth while.

Just trying to help you here, not beat the dead horse.
 
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Ditchplains1

Ditchplains1

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Phydough, Ruger,
I'll head to NAPA tomorrow and pick up a pair. The shop uses only NAPA parts anyhow and it won't hurt anything to replace them now.
I tried to tape the sound while driving with my phone. Loaded it into my computer but the FRF won't let me load a MP4 video. The quality of the recording stinks anyhow, but you can hear the faint whine if you listen....
Thank you all again,
Eddie
 
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