RDJ, this is a common problem here where we work. What series D6R do you have, I would presume it is a I. If so, there is a trash fan available through the Cat parts system, that has a curve (I know they all have curves,this is more of a hook) on the end of the blade. With the engine runnng and fan at max suction, debris will get sucker forward, hit the fan blade and centrifugal force will fling the material out and around the rad cores. Fan blade shape from the end, looks like a "j" rather that a bent"i". install of this fan requires removal of the shrouds to both left and right of the fan, allowing this debis (grass /leaves etc) to go around the radiator, rather than get stuck to it. These fans have a bead of hardfacing on the end where the debris exit, and will require replacement, dependent upon inspection. Also D8R (I) rad cores will fit into the D6R (I) should more cooling capacity be required.
I have more info if req.
IU