My truck has a vibrating/rattle noise (sounds like metal on metal) between 1200-1400 rpms only when the truck is fully warmed up. It is driving me CRAZY! I have checked every accessory on the truck to ensure everything is tight, and . . . .no luck. I bought a scope to try and locate the sound and I can hear it louder on the intake manifold and the fuel rail. Any ideas?

Just take it in I suppose . . .

 

When my 2 injectors went the truck had a small vibration and you could see the vibration the the mirrors! Wasnt really a noise that I heard! if it sounds like metal to metal you could have a rocker that is getting loose. Is the sound coming from the rocker box?

 

Rocker box? Is that the black "Cummins" cover? If so, I did put the scope on it, and I can hear it there, but it is louder on the intake and the fuel rail.

 

No that is just a cover! the rocker box is the top little lid, kinda like a valve cover. It is a thin aluminum cover under the black "cummins" cover!

 

Thanks . . . . .I'll try and check it tomorrow when the motor is warm again.

 

becuase before I ran my overhead I had a little sound like that and it was a loose rocker nut