I have a 2013 sportsman 400. Out of warranty of course!. I've been loosing coolant for a while but not enough to think twice but have always got a faint scent while riding.The other day I was riding in snow and steam started to come out and I could smell antifreeze real bad. So theres a little hole above where the exhaust where it comes out of the motor and its leaking the coolant on the exhaust. Any idea what this is? Looks to me like there's supposed to be a tiny bolt in it?