I crank tractor and flip parking brake switch and parking brake releases in a second or two. I work for a while and parking brake light flashes when I change direction but neve actually applies it. This goes along for a while and while I'm traveling parking brake light will illuminate and tractor will lose power to move but parking brake is not really engaged. I can turn machine off and recrank, then tractor works like a new one and the only time I even see the parking brake light after that is when I turn it flip the switch for it. Any ideas? It's like I have a hydraulic problem that is completely rectified by cycling the tractor off and back on.
I have ordered the proper adapter for my test gauge to measure the pressures from test ports on the transmission. I'll post those once I have them.
I connected a 300 psi gauge to the System Pressure port today and I have 230 psi at this port after I crank the tractor. Releasing parking brake momentarily drops this pressure to 150 for a second, but then its right back up to 230. Then after 10 minutes or so of moving the tractor around I can watch this pressure drop pretty quickly to sub 100 psi and by design the parking brake is applied. I can turn off tractor and let it sit for a few minutes (5 minutes at the most) and recrank and I then have a strong 240 psi on my gauge. I will stay in this 240 to 230 range for quite a while (20 to 30 minutes maybe) before repeating the scenario. Any ideas?
I'm suspecting aeration in the trans fluid is some of what's going on here. That would explain how I can restart the tractor and it goes back to working right. The air bubbles go away when it's resting.