I have a 13" MBP late 2009, 2.53 GHz, 4 GB RAM, and on OS X 10.8.3. As soon as I boot up the fans start going at the highest rpm and like I mentioned the kernel_task is always at around 90% when no apps are being run. I read somewhere that I should try safe boot and see the effect but there is none.
Any ideas as to what is causing it?
I found a way to fix this issue, thought I should post it since it might help someone else. Granted this fix kinda worked for me since my fans are at their full rpm but you should read the explanation first and then choose to follow the steps yourself, anyways the info. is here: http://www.rdoxenham.com/?p=259
sudo iosnoopto show harddisk activity. Do you see lots of output to the command? If that's the case, could you add several lines of ouput to your question? Still in Terminal, type
sudo tail -f /var/log/system.logto open and follow the system log. Are there warnings or errors? (Exit
tailwith <Ctrl>-C.) Again, it would be helpful that you shared your findings in your question.