My cub cadet Lt1018 hydrostatic drive B&S 18.5 HP is leaking oil out of what apears to be a pump or breather I'm not sure what it is.(round plastic disc with a brass breather in it and lines hooked up to it). It has an oil line a gas line and a line to the carb hooked to it. At low throttle it bellows smoke out the exaust like oil is being sucked thru the carb with the gas.

Can any one tell me whats wrong and /or how to fix it.

Thanks