If I felt my units were getting too hot I can modify the case for better air flow. You didn't seem to tell why you didn't try fixing it.
I have two hard disks. My older disk(4-5 years old) is Western Digital 250 GB (WD2500KS). That disk I use for torrents to expand the life of my new one. It acts strange when there is no reading or writing on it. It gets very hot over 55 degrees and when I start my torrent client it begins to cool to 46-48 degrees. Every diagnostic software I used shows that it has 105 bad sectors. Could it be the reason? And why it gets hot when there is no such activity on it?