I believe the 3126 is similar to the C7 and if so, the bearing you are referring to (about in the center of the block and drives the fan on rear rad engines) is not the water pump, but rather an idler/fan pulley. The water pump is mounted low on the engine and most, except for some C7's like mine, have a separate belt. Regardless of that, I have read where others have added additional tubing/hose to extend the zerk fitting to a more accessible location. Another option might be to replace the existing bearing with a seal bearing like many of the the C7 engines have. I'm willing to bet our resident CAT expert Brett (wolf10) will jump in at some point with some specific info on this topic. Good luck.
Lou
05 Travel Supreme Envoy
CAT C7