D&GExcavating
Senior Member
The 555 motor is considered a lemon by the standards of Cummins, Versatile also produced a 4wd tractor with the 555 motor and called it the 555, it's nickname is the trouble 5.
General advice is to stay away from that motor and stick to the straight 6's or bigger V8 motors, like the 903.
Massey Ferguson made a 4wd tractor with the 903 and it is a legend.
I've heard that the 903 Cummins had bottom end problems. We have a 1979 Cougar 3 and a 1980 Cougar 3 that we use for pulling industrial disks and tandem sheeps foot packers. A couple weeks ago i was pulling a disk with the 1980 which has an NT855C Cummins in it. I let it idle for about 20 minutes over lunch and then i disked with it for about 30 minutes. I shut it down for about 2 hours and then came back and tried to start it up and it would not start. It smoked but wouldn't start. Well i messed around with the solenoid on top of the injector pump and it finally fired up but it had a nast klack in the valve train. So we took the rockerboxes off and pulled all of the pushtubes and didn't find anything. Took it to the local truck shop and they tore her down and found that there were absolutely NO rings left on all 6 pistons. Most of the pistons had huge holes in the sides. They think it was worn out injectors pouring way too much fuel in. So now shes all rebuilt and has almost twice as much power as before.