When buying a used tractor, inspect the tractor's wear and tear, examine its electrical system, check for signs of leaks, look at its tires, and thoroughly examine its engine. Always test drive the tractor as well, and pay attention to obvious problems, including tight, loose or floppy steering. Also pay attention to the functionality of the clutch, brakes and hydraulic lift assembly.
All used tractors exhibit wear and tear, but you should determine whether it is the result of normal use, overuse, lack of maintenance or an accident. Normal wear and tear should show the same amount of use throughout the tractor, such as on the foot pedals, floor mats and tires, and should reflect the amount of time the tractor has been in use. Poor maintenance and overuse is usually obvious, but new paint and new seals or rubber around the cab, engine and rear differential could indicate the vehicle was in a fire.
Frayed electrical wiring, damaged cables or low water levels in the battery all indicate items that must be replaced. Oil or other fluid leaks can be signs of serious problems. Check the hydraulic system, and check the dipstick to see if the oil is worn or contaminated.
The O-rings on the crankshaft should look normal, and the tractor should come up to speed quickly even when cold. A piece of paper placed over the exhaust shows oil if there is a problem with the engine's ventilation system.