Fixing a hydraulic leak might be as simple as tightening a hose fitting. Finding the hydraulic leak can often be a much more challenging task. Luckily, tractors have relatively small hydraulic systems and few hydraulic components. So there are not many places for hydraulic fluid to leak from. Gravity, vibrating parts, dirt and debris all combine to mask the origin of hydraulic leaks. You may find that the tractor hydraulic line that drips may not be the source of the leak.
Turn off the tractor's engine. This also turns off the hydraulic pump and depressurises the hydraulic system.
Clean the area you think might be the source of the leak. Wipe away dirt or hydraulic-fluid residue.
Restart the tractor engine to run the hydraulic pump and pressurise the hydraulic system.
Inspect the area you suspect is leaking. With a flashlight, look for drips or trickles of hydraulic fluid.
Inspect a larger area if you can't find the leak. The dripping evidence of a hydraulic leak may occur far from the actual leak, since hydraulic fluid can run down surfaces.
Operate the hydraulic components you suspect may be leaking. Inspect them for leaks as they run.
Relieve the hydraulic-system pressure before attempting to repair any leaks. Ensure the tractor engine is not running, since the engine usually operates the hydraulic pump.
Securely tighten leaking hoses or tubing nuts.
Replace the hydraulic tubing or the cut or damaged hoses.
Reseal leaking fittings on hydraulic components. Unscrew the fitting from the component with a wrench. Remove and replace O-rings or other seals on the fitting. Then screw the fitting back onto the component.
Replace the components you may be unable to reseal, such as the tractor's hydraulic pump.
Remove and reseal leaking lift cylinders or other hydraulic cylinders. You can usually purchase a seal kit for each cylinder -- containing every seal needed to rebuild the cylinder.
If you find leaky hydraulic cylinders and you don't feel comfortable resealing them, replace them.
Don't search for hydraulic leaks by feeling around with your hand. Pressurised fluid squirting through a pinhole can puncture the skin.