Engine Smoke

[dav]

I have a Massey Ferguson 1010 16hp Diesel 4wd that blows puffs of white smoke when the engine is ran above 2500 rpm, the max is around 2650. It seems to lessen when the engine warms up and also when its under a load. The tractor has done this scence I bought it. It now has only about 190 hrs on it about 50 of witch I have put on it I changed the oil at about 150 hrs and it hasn't used a drop, it seems to run fine lots of power. I thought it might need a thermostat because it seemed to run very cool, you can easily hold your hand on the valve cover when at normal temp, so I replaced it but no temp change and it still smokes. I asked my dealer he said it shouldn't smoke after warm up when it's not under a load. Any opinion would be greatly appreicated this is my first diesel and if it needs service I'll be sure to get it done. Thanks All.........