Ground Wires/bolt getting hot

Currently I am running 2 400c compressor set up from Viair, all my ground wires are connected to the same bolt and for some reason the bolt seems to get very hot after a short period of running. Not sure how I can fix this? Maybe a dirty connection? Any advice would help

Increase the size of your ground wire.

If you’re running both compressors to the same ground you might want to use at least 4 gauge jumper cables, or 6 gauge from each compressor to your ground.

-Kris

That’s what my initial thought was, I’ll give that a try thanks