Greetings from Southern Illinois. I'm new here and have a question about my grader I recently purchased. Its a 1976 Champion D715, overall in pretty good shape, a few leaks here and there. While inspecting it I noticed that the left lift cylinder would leak down slowly allowing the blade to drop, didn't think much of it, figured the cylinder needed rebuilt as several others were leaking externally. Anyway, fast forward, rebuilt the cylinder, seals looked okay but installed new ones, isolated the cylinder, the float valve block and the main valve body. Best I can tell I have a problem in the float valve block because when I take it out of the circuit the cylinder does not leak down. The solenoid valves work when the switch is operated as the blade does fall on both sides. I have 12 volts on the solenoids with the switch on, and nothing with the float switches off I've checked the solenoids, they both operate when energized, o rings look good but I'm going to replace them. Switched the solenoids from top to bottom with no change. What do you think I'm missing? Do you think I could have a small crack inside the float valve block? Also, this only happens with the blade in the up position, it will lift the front wheels off the ground and hold when postioning the cylinder in the down position. Thanks for any help you can give me.
Not sure if you have the same valve, but on a newer machine at work ('92 720) I had the same problem. Local Champion mechanic at the time (factory rep) showed up, put some new o-rings in the valve, end of problem. I'd start there..........
could be the valve is distorted. had theat same problem on a 81 715a. the aluminum float valve is attached to the cylinder with a steel plate. the dissimiliar metals will react. actually bent the bracket and distorted the valve. the seat is now out of round and won't seal. might be something to check out
Okay, got the problem fixed. The valve is actually steel so it was not flexing. One of the internal pieces was broken. We dissassemble the entire valve, found the broken pin, machined a new one put it back together and it works fine. Thanks for the ideas.