I have been on here quite a lot with all my issues. I have a project MacBook (early 2009, a1181, which is running OSX High sierra and Ubuntu along with a bootloader, refit or fEFInd, can't remember at the moment). The macbook gets really hot when charging, so much so that my friend got a burn just from picking it up!
The heat is on the bottom corner closest to the MagSafe port. The MacBook randomly shuts down and it takes longer for it to shut down when it starts up cold.
The shut down is so abrupt that you can hear the hard drive's arm clunk. When I try to power it on again, the indicator light turns on for a split second but goes out (hard drive also clunks as soon as the light goes out).
Is this a power issue? If you think you know how to fix it, please let me know!