i had this problem, and resulted in a headgasket popping!

gearbox mount snapped, engine kicked, alternator pulley chewed straight thru the samco, coolant poured out, engine overheated before i knew what was happening, and headgasket failed.

worth sorting sooner rather than later, 1 simple rubber mount cost me a fairbit of cash, new hose, new HG, head skim, plenty of hours labour etc