I just purchased a 2004 F250, V8 6.0 diesel truck mainly for towing. It has 129K miles. My trusted AAA approved mechanic looked it over and fixed everything that needed fixing, (almost 3K) and declared it worthy to make a 2400 mile trip part of which nvolves towing a 9000 trailer 1400 miles. We drove the first 1000 miles without incident (no towing yet). In the last 75 or so miles, when we hit 1500 rpm and about 55 mph (esp, when the truck shifts into higher gear and the rpm drops) the whole thing starts shaking. Once we increase the rpm, or go faster, the shaking goes away. The check battery light also came on sometime after the shaking started (maybe it came lose, although neither battery looks like that). Any tips? We are outside of our home state, away from my mechanic and also ould use some help with tips on how to find someone who can be trusted in St Augustine FL, or somewhere nearby. Thank you for your help.

 

With the check battery light, I'm guessing the shaking has loosened the battery clamps, open the bonnet and see if they are tight, could be a bad connection if the battery clamps are loose and that might be setting off the light, or the battery is on its way out. If they are tight and secure on the battery terminals, start the truck and if it takes a long time to start and is having trouble starting the battery is either flat or cant hold much charge anymore.

A month or so back, I drove a Holden Rodeo back to our workshop that would shake like anything at around 3000 RPM and it was very down on power, we found that it had next to no oil in it. A warning with this is don't rely on the oil warning light to come up, because when that comes up is pretty much when the car has lost oil pressure and it'll be doing severe damage by starving the engine of oil. Just check your oil level and if its fine, discount this.

Sorry I can't help specifically more, these are just general tips we've found with issues like these.

 

Thanks. I just had an oil change, bu when the engine cools down I can check the oil. Mine shakes at lower rpms (only around 1500) and specific sped (around 55 mph) when the transmission shifts up to higher.