Vibration at 1300 rpms

Could your drive shaft be out of phase? Or maybe the U joint has too much play?

 

Sounds drive shaft wear ! Put your arm down through the chassis nag grab the shaft, try lift it up and down , if you feel a slight knock that's your problem, you shouldn't leave it too long because if it's a splicer it could snap at any time

 

Sounds drive shaft wear ! Put your arm down through the chassis and grab the shaft, try lift it up and down , if you feel a slight knock that's your problem, you shouldn't leave it too long because if it's a splicer it could snap at any time

 

may be tranny flange play

 

I am having a similar issues. But mine shakes at a stop when the idle is kicked up to 1300. It's a 99 12.7 ddec 4, 500hp. That and it starts like crapp if it isn't plugged in even at 40 degrees. I also noticed if the engine isn't all the way up to operating temperature the Jake sounds funny like it doesn't kick off all the way when you push in the clutch. It was rebuilt 400,000 miles ago. I'm not trying to high jack this thread the issues just seemed similar. Any ideas? Something bad in my head?

 

Are your jakes sticking on? It would be hard for the engine to run at low rpm's or idle if they weren't opening properly

 

They could be. I bought it with 300000 on the overhaul. I haven't ran the rack yet. Could the valves be out of adj cause the hard starting and the Jake to act up when the engine is cold? It's just weird, I wouldn't think it needs another rebuild yet. Its like a half miss or less its very slight.

 

Hhmm, does it sound muffled up to 1300 rpm?

 

simply, YES! Valve and injectors being out of adjustment can make a big difference in smoothness of idle, as well as fuel mileage.