PTO issues / post driver issues?

   / PTO issues / post driver issues? #1  


Super Member
Mar 27, 2007
Bay Area, CA
Power Trac PT1445
Has anyone had an issue with the PTO solenoid not fully functioning? Or trouble with the PT post driver?

I went to use my post driver two days ago, and while getting it ready, greasing, cleaning, etc., I turned on the PT (throttle a little above idle), and powered up the PTO hydraulics via the PTO switch. I wanted to raise and lower the driving weight to grease the rollers and the track the rollers run in/on. For those who aren't familiar with the post driver, 100% of the PTO flow goes out to a pressure relief valve on the driver and then on to a lever valve on the post driver that can be diverted to raise the post driver, or dump it. The default (neutral) setting of the valve has all of the PTO flow into bypass to the tank.

When I initially went to flip the PTO switch on, I could see the input hydraulic line flex, but when I moved the valve lever to raise the driver, the cylinder didn't lift. Cycling the valve lever didn't seem to free it up, though I could see the input hose flexing as if the pressure was rising and falling under load. Cycling the PTO switch didn't seem to free it either.

After a few minutes, of exploring and looking, it started working; the cylinder raised and dropped as it normally does. So, I finishEd servicing the driver, and put it aside.

The next day, I called Terry and unfortunately came up with nothing actionable.

Today I get it out to drive a few posts, and same issue. Initially, it didn't work, then after five or ten minutes, fiddle-faddle, poof it worked. Again, I could see the hose flex when the PTO switch was first turned on, but no lift.

I thought that I remembered some older threads here of some folks having issues with rusty solenoids that didn't function, or didn't intermittently function, but I can't seem to find the thread.

What I haven't yet done is hooked up another PTO powered device to try to see if it is a PTO solenoid/PTO wiring issue.

Any ideas?

All the best,

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   / PTO issues / post driver issues? #2  
Presuming the driver raising cylinder is a 1-way deal, I'd suspect air is leaking into the line & you have to blow it thru before it will take a load. Somehow, the oil might be leaking back into the PT via a bad internal seal, valve, or port.
   / PTO issues / post driver issues? #3  
So yea on the solenoid. Undo the screw / nut on the magnet. Pull the magnet off, use a bit of emery to remove the rust. Put it back together. That said. Solenoids die. Run a 12volt directly to it if cleaning does not fix it to test.
   / PTO issues / post driver issues?
  • Thread Starter
@zzvyb6 I did fiddle with the system a bit to orient it in a way to better flush out any air in the system, but I wasn't able to change the behavior. I think that the cylinder volume for these post drivers is larger than the volume of the hose to the valve, so normal use flushes air very quickly.

@woodlandfarms Thanks. I will give it a try. Given the minerals in our water, it wouldn't surprise me if there was some build up along the solenoid shaft. Did you add any rust inhibitor / dry lube / silicone lubricant?

All the best,