My friend and neighbor Steve Loree specializes in Engine Mounts.  http://www.loreeair.com/#!engine-mounts/c250n   When he repaired a crack in our RV6 mount he found two more that were hiding under the Powder Coat.  Most manufacturers like Powder Coating since it is tough and cheap to apply, it is also elastic.  He strips any mount he repairs and repaints it with Polyurethane, preferably white.  Just thought I would pass this along.

Steve Colwell   Legacy