I have a 91 explorer, motor was replaced by a motor out of a ranger, i cant remember what year it was. By now it probabally has about 110,000 on it. About this time last year it started puffing smoke when i pull of from stop signs and such, and maybe a little when i shift gears. What in the world could be the problem? It stinks, too, even when you dont see the smoke coming out, it smells bad and its not the converter. I have been told it most likely needs new valve seals..... is this right? Thanks, Rob

 

Could be valve seals... Are you loosing any fluid anywhere? Does it smell like burning oil?