How to Figure Out if Loader Control Valve or Cylinders Have an Internal Leak

When either your loader or your bucket drift down when your tractor is powered off, but you can't find any leaking oil either on the outsides of the hydraulic cylinders or the outside of the control valve body, it can be tricky to figure out where the problem lies. Usually there is a leak somewhere with the hydraulics, but the leak is internal. Before you start replacing the cylinders or the loader control valve block, or tearing them apart to rebuild them with o-rings, it's great to run a little test to see where the problem actually lies. This video shows a simple test you can do to learn where the internal leak is happening.

Step 1. Identify which line from the control valve leads to which cylinder. There will be two lines going from the loader control block to the bucket (tilt) cylinders, and two lines going to the loader (lift) cylinders. Starting with where each hose connects to the valve, trace that hose up to the loader's connected steel line, and then trace that down to the hoses going from that steel line to the cylinders. Identify each hose and port in some way - for example, a piece of different colored zip tie on the male and female ends of each coupler, so you can keep track of which is which.
Step 2. Release all pressure on the loader by lowering the loader and bucket completely, powering off the tractor, and moving the joystick several times.
Step 3. Switch around the hoses where they connect to the hydraulic control valve - attach the loader (lift) hoses to the ports normally connected to the bucket (tilt) hoses, and vice versa.
Step 4. Power your tractor on and raise the loader and retract the bucket - not way up in the air (for safety concerns) but just enough off the ground that it's obvious if one or the other drifts down.
Step 5. After several hours (maybe overnight), check if the same thing is drifting down. For example, in our video, it was the bucket that was sagging before the test. When we rang the test and came back several hours later, it was again the bucket that was sagging. This told us the problem is in the bucket cylinders, NOT in the valve. If, after switching the lines around, the problem had switched to the loader (arms sagged), then we would know the leaking was happening inside the valve.
Step 6. Again, release all pressure on the loader / bucket and replace the lines to the correct ports. Either replace or rebuild the bad part - in this video, the cylinders will need to be rebuilt. If the loader arms had drifted down, then we would have needed to decide what to do with the valve - either rebuild it or replace it.

We do carry a complete replacement loader control valve, which works to replace most valves on tractors up to 80 HP. It comes with the items, and instructions, to set it up as open center, closed center, or power beyond. In some situations you do need to do some research figuring out where the tractor's pressure and return lines are, as you'll have to connect the valve to both of those. In this video, for example, where the control valve is built right into the body of the tractor, this is a little more tricky to figure out and would typically involve taking a look at the tractor's manual. In other situations, when your tractor's valve is right out in the open and not embedded into the tractor's body, it is pretty straighforward to replace it with the control valve we carry - several hydraulic fitting adapters and possibly drilling a few extra mounting holes in your valve bracket will get the job done. The new replacement valve can be purchased here:

https://www.shortlineparts.com/koyker...