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Originally Posted by bunt  rpms were about 1500 in gears 2 and 2, throtel lever was set to just above stall. engine was lugging when it hesitated backfired. Ran for approximately 20 seconds, because I could see smoke coming out of intake pipe and put hand over exhaust and it almost stalled. |
There is nothing wrong with your tractor but the operator could improve a little. The conditions that you described are exactly what I had in mind when I started reading this. This problem was much more common with 2 stroke Detroit diesels in trucks. The driver would stall the engine in a heavy pull and, if conditions were right, the engine could start running backwards.
Gas engines won't run backward because they suck the fuel in through the intake valve and exhaust goes out the exhaust valve. If you turn it backward it will be sucking though the exhaust valve. Since there is no fuel source in the exhaust system the engine will not start. Diesel engines only suck air through the intake valve. The fuel is added directly to the combustion chamber by a separate injector nozzle. If you turn the diesel backward it will still suck air in through the exhaust valve and the fuel was still added by the injector nozzle. The engine had air, fuel, and compression so it started. I would not expect the injector pump to work turing backwards on all diesels so this may not be possible with a lot of engines.
There are some things that you need to do to prevent this from happening again. When you are working the tractor run the engine at its rated speed (wide open throttle on most tractors). The people who designed your engine chose that
RPM because it will give the best fuel economy and make the engine last as long as possible. Your engine has a governor that will maintain that speed... let the governor do its job. Lugging the engine is pretty hard on it and could reduce its life. Think about chosing the right gear to get the ground speed that you want instead of adjusting the throttle. It the engine is lugging down (200-300RPM?) then shift to a lower gear. You do not have to be running wide open when you are just putting around but give it soem more throttle when you start working it. Its kinda hard to believe, but you will put less wear-and-tear on an engine that is running at its rated speed than if you lug it a lot. I started running heavy equipment (backhoes, dozers.....) at a young age. I was instructed to push the throttle wide open in the morning (after warm up) and leave it there all day. This advice has served me well and I think that it will work for you to.