More Hard Starting
It's that time of year again. Traffic on this blog always picks up when it's cold. Guys that used their diesel tractors all summer without problems are wondering why they won't start.
Before we go any further: Stop cranking the tractor if it won't start in 2 or 3 revolutions. You're putting unnecessary wear on the engine. Typically, if a diesel won't start in three or four seconds - it won't start. There are some exceptions in the case of injector bleed down or dry rings, but mostly it's not going to get better by cranking.
I wrote extensively about it here last winter.
One of the dynamics is the physics of Lead-Acid batteries. Over time, heat reduces their potential to generate current. But then it's compounded because when they are cold they actually can use less of their available potential. So over the summer, your battery was being decayed by heat and now the cold saps it of the ability to release the remaining energy. Even with gasoline autos, most starting problems appear in the winter.
Make sure your glow plugs are actually heating. I had a short last year and my glow plug indicator was lying to me.
You can try force feeding your diesel with a 1500 watt blow dryer or a heat gun, but I'm not sure that will make any difference with an ice-cold oil bath air filter. Let me know how that works out.