No, that's normal. That process is essentially the nerve system of the entire OS. You do NOT want to go messing with that process unless you are looking to compound your problems. Mess with that process, and the system will come to an immediate and abrupt halt in the form of a kernel panic message.
It's also totally explained by a bad HDD. With a HDD functioning normally, whenever kernel_task requests data, it gets it in a pretty short order of time, and then goes back to sleep. Your drive isn't functioning properly, so it takes longer for the data to get to kernel_task, so it keeps sending out requests for the data. Kind of like an impatient person saying, "Come on! Come on! Come on!" and tapping their fingers on the table.
Here's a quick facts of life chat about computer HDDs. They fail, and they fail quite often. I work as an Apple repair tech, I also dabble in Toshiba laptops, and before that I did Dell stuff too... HDD and PSU replacements are probably like 60% of what I do. HDD failures might well be the single most common failure of any computer failure. There are a bunch of moving parts, and then the read/write heads are only a tiny fraction of an inch above the platter, which is all kind of just tempting fate.
So, since you so far aren't really responding to the softly-softly approach, here it is straight up. You can continue wasting time, trying to find some reason why it can't be the HDD, meanwhile if it IS the HDD, it will continue to fail and you'll lose your chance to back everything up soon. The alternative, is you can stop wasting time and either install a new drive or take it somewhere for professional diagnosis. The sooner you get started on this, the sooner you'll be done. If I'm right, and you continue to wait, pretty soon you won't have the luxury of doing this on your own time. The drive will fail, all your data's gone, and until you get things fixed, you're dead in the water. Take your pick, because those are your options at this point.