Have been having a recurring, but intermittent sound which seems to be coming from the undercarriage.
Vehicle:
2015 F-350, SRW
6.7L V8 Diesel
6-Spd Auto trans.
Crew cab/short bed.
approx. 12k miles, sound first appeared around 5k miles - was careful to not tow trailer until close to 1,500 miles on truck.
Sound is a high pitched whistle that oscillates up and down. The speed of the oscillation ties to the speed of the vehicle, independent of engine speed. It is very consistent when towing a 5th wheel. (10k lbs weight of trailer, roughly 1800 lbs tongue weight) Very inconsistent when not towing. Most noticeable at speeds around 5-10mph, above that it either stops or blends in with road/engine noise. Also disappears after truck is fully warmed up.
Dealer thought that there could be some relationship with a TSB. Replaced "transfer case rear output shaft seal. (ssm 44925)
After that service, the sound disappeared for approx. 200 miles of towing the 5th wheel. After camping for a week, sound re-appeared as we pulled out headed home. Sound now seems to have changed and at times there are two separate, not synchronized oscillations occurring - and is now slightly lower pitched.
Last week left it overnight at the dealer, after hearing the noise consistently for about a week - every morning as I started driving, test drove the next morning with the Diesel tech - and as Murphy would have it...no whistle!
I'm at a loss and am now waiting for it to 'get worse' so I can take it in to get better. Next step might have to be parking by dealer with 5th wheel attached overnight to test drive with trailer, while cold. That usually guarantee's the sound will be heard and is at it's loudest.
Sorry for the lengthy description - THANK YOU for any thoughts/comments.
I have video or audio files of the sound, but am not sure how to post them here. Again - thanks!
Vehicle:
2015 F-350, SRW
6.7L V8 Diesel
6-Spd Auto trans.
Crew cab/short bed.
approx. 12k miles, sound first appeared around 5k miles - was careful to not tow trailer until close to 1,500 miles on truck.
Sound is a high pitched whistle that oscillates up and down. The speed of the oscillation ties to the speed of the vehicle, independent of engine speed. It is very consistent when towing a 5th wheel. (10k lbs weight of trailer, roughly 1800 lbs tongue weight) Very inconsistent when not towing. Most noticeable at speeds around 5-10mph, above that it either stops or blends in with road/engine noise. Also disappears after truck is fully warmed up.
Dealer thought that there could be some relationship with a TSB. Replaced "transfer case rear output shaft seal. (ssm 44925)
After that service, the sound disappeared for approx. 200 miles of towing the 5th wheel. After camping for a week, sound re-appeared as we pulled out headed home. Sound now seems to have changed and at times there are two separate, not synchronized oscillations occurring - and is now slightly lower pitched.
Last week left it overnight at the dealer, after hearing the noise consistently for about a week - every morning as I started driving, test drove the next morning with the Diesel tech - and as Murphy would have it...no whistle!
I'm at a loss and am now waiting for it to 'get worse' so I can take it in to get better. Next step might have to be parking by dealer with 5th wheel attached overnight to test drive with trailer, while cold. That usually guarantee's the sound will be heard and is at it's loudest.
Sorry for the lengthy description - THANK YOU for any thoughts/comments.
I have video or audio files of the sound, but am not sure how to post them here. Again - thanks!
