New owner of a 2005 F250 Turbo Diesel, Super Duty. Started to tow a light trailer (25 ft, about 4,000 lbs). Towing and accelerating to get up hills to about 3000 rpm, then when I release the gas pedal there is a funny, almost high-pitched slight shuddering - very weird. Can't figure out what it can be. It comes after rapid acceleration when I take my foot off the pedal. Any clues? Hard to describe, almost like a thonk, thonk, thonk, in rapid succession. It also happens (although much less) without towing I noticed today and not as pronounced.

Any help is appreciated. Otherwise - love this truck!

 

Is it coming from behind and under you? I would have the u joints on the drive shaft looked at

 

Thanks so much. Can't really tell whether it's behind but definitely under me. Will check it out It is especially loud going up a hill, after acceleration, then taking your foot off the pedal.

 

When your new to this and don't know who to go to for help - these forums are great. What I'd really like to ask is how to find a diesel shop locally (Central NJ) near 8A on the Turnpike so I don't have to go to the Ford Dealer and pay probably 3-4 times for any diagnostics. Anybody know anyone? Thanks again everyone.