Problem seems to have been caused by build-up of debris and caked dirt between radiator and oil cooler, restricting air flow, and causing overheating of hydraulic fluid, which led to associated screeching noise and eventual overheating of mower belt pump which led to belt failure. Was unable to remove radiator for cleaning between radiator and oil cooler (that requires removal of the dump bed, according to dealership) but was able to elevate rear of radiator enough (by disconnecting hoses) so that caked debris could be broken up by hand and cleaned out using vacuum, air hose, and water hose. After cleaning, problem seems to be resolved. Question is how to prevent this from happening again. Debris is apparently being sucked up thru wide open fan shroud when mowing. I've been pretty conscientious about trying to keep the radiator and oil cooler area clean with air hose and water hose. Am considering covering the open fan shroud with wire screening. Has anybody encountered this problem? Any solutions to suggest to keep this from happening again?