i have driven my friends for 3 seasons now  and havent had a problem, his dosent have anything, the amount of heat in the engine bay  keeps all the snow melted and water dry,if you cut a trail and shut your machine down right away  or it wasent warm  the ice could build, there are  more than 10 machines that i know of that are built like this with no problems of build up.the hole allows the engine bay to breath better .