I have a F250 2003 6.0 diesel. A couple of days ago I know my truck started shaking under throttle. I poured the diesel kleen to it, change the fuel filters, fuel pump, and changed the oil. The problem has diminished dramatically, now as the truck is going up through the gears(automatic) i can barely feel the shake, but when it goes into overdrive around 55-60 mph and the rpm's drop to around 1700 it still shakes. The shake gives you the same feel as a wheel coming loose. Need help.

 

Maybe an engine mount?

 

Maybe a wheel is coming loose?

 

I've checked all that...that was the first thing. Thanks

 

What's your fuel pressure looking like at the filter housing?

 

Taking a shot in the dark, here, but I would think maybe a bad injector or two.

The HEUI injection system relies on oil pressure to fire the injectors, and new oil could affect the way the injectors fire.

The fact that the vibration lessened after you changed the oil points to a misfire, has it thrown any codes?

 

No codes what so ever. Also there is no smoke. The injectors is what I'm leaning toward also. Thanks

 

I would agree with the fuel injectors but if the pump is producing less then the min requirement that would cause the injectors to go very quick. Min pressure of the fuel to the filter housing on the engine is 40psi.

 

Good point, Surge08.

How would you measure pressure at the filter?

 

There is an inspection port on the filter house with a fitting and copper washer.

I will take an picture in the morning to point it out

 

My Excursion had a shake like that (02 7.3 auto) and it turned out to be a balance weight came off the flex plate/flywheel