I've got a 2000 rancher 350 and it's blowing oil in the air filter box through the crankcase hose and the oil temp light stays on. What would be causing this? Its still got alot of power and doesn't smoke.
Oil in the airbox can be cause by several things, one of which is gas bypass at the rings or valve seals, pressurizing the crankcase. Any blue smoke?
Even a slight amount of blue smoke at start up indicates worn rings or valve seals.
Another is a dirty air filter, causing too much suction in the airbox, and letting oil be sucked up by the crankcase vent hose. An obstruction (mouse nest for example) in the airbox snorkel will do the same thing
I agree with Sub. I would start by cleaning the air filter, replacing the rings, and replacing the valve stem seals. I know that's a lot of work, but that's about all I know to tell you to do. The only thing is, I don't know why the oil temp light would be staying on, unless that's a completely different problem.