Yes you do need to find some loose snow to get them to cool down cause otherwise the heat exchangers aren't getting cooled down. On the otherhand I don't think they should have overheated that easy. I've been running in warmer than 32 degrees with minimal snow this year just to ride and never had any trouble. Was this the first time you have ran your new sleds. I wonder if there could be an air pocket in the system that would do that?