Chris, Don't sweat it. Diesels smoke a little at startup till they get sufficiently warmed up to provide an efficient burn. The older direct injection Kubota engines would scare you to death. Smoke under load is also perfectly normal as a result of the governor action on the fuel rack providing more fuel for the demand. (ever notice a semi going up a hill or accellerating?) A puff of smoke when initially putting the engine under load is normal, if the smoke continues as well as a steady rpm drop off, it's an indicator that your overloading the engine (lugging), and is not good. If you back off on the load, the rpm's should rise, and the smoke should clear up. The HST guys should be pretty familiar with this scenario. Chances are you just never noticed this before and possibly you're working the machine a little harder than usual.
