Is there an option to place a fan in front of your drive?
so you have case front, fan then drive
Does your case have a rear fan? What case is it?
Do you have and use a floppy? if not you can take it out and leave the space above the drive. leaving the opening there may help air cool the drive it its right near that opening....this assumes you have a rear case fan pulling air out of the case.
I last ditch effort may be a hard drive cooler with a fan or 2 blowing of the bottom of the drive.
This unit from Vantec may help, but i hope you have enough airflow in your case to get rid of the heat once its off the drive...once again, a rear fan is recommended...
It screws to the bottom of the drive and needs a bit of room under it(and empty hard drive slot under the drive you want to cool)....if you have room it may help and is not expensive....