log splitter problems.

What would cause a splitter ram to extend on it's own. The minute you start the engine, the cylinder extends - doesn't matter the position of the valve. Then the cyl won't retract unless you shut it down and manually push it in.

This is a home-built unit with no pressure gauge, using a vane style belt drive pump.

Pulled the Prince valve apart hoping to find a torn O-ring but it doesn't have any orings on the spool.

Would a clogged filter (Spin-on cartridge on the return line) cause this?

Could the piston seal be torn/damaged on one of the edges? 4.5" tie rod style cylinder rebuilt 4yrs ago.

Before I start tearing into it, I was hoping someone would have an idea of where to begin (I'm thinking a gauge on the pump to see what kind of pressure, it won't split a 6" oak chunk).

I would still be looking at the valve I think something must be wrong there.

I had a similar problem with my log splitter. Except I got sprayed with hot hydraulic fluid as it extended on its own. Turns out the nut on the end of the internal ram came off (I welded it back on)

don't know how its rigged, but I'm leaning towards restricted return, if you looked valve over-making sure it was centering out? end bolt/spring not worked loose?

My splitter does the same thing. When it warms up it works normal. That's what mine does. Stan

The new valve's spool looked undamaged, bore looked nice and clean, the seal at the back end was good. Detent on the return clicks, and there's full range of motion.

Hadn't thought of the rod coming off the piston... it'd be internally bypassing hence the lack of pressure to split. On return the piston would go back but the rod would stay in place.

4 yrs ago when I rebuilt it, I couldn't stomach the $87 for new seals on the hokey multi-ring steel piston so I turned a new one out of aluminum, $4 double lip seal and I was good to go.

I don't recall locking the nut down with a cotter or even loctite.

I dug some gauges out, one goes to 3000psi, I should be able to put it on the T at the inlet to the valve to see if I'm getting pressure.

Thanks guys

Can you hear the system going over relief (and maybe the engine lug down depending on its power)
when it hits the end of the stroke or does just come to then end then stop and sit there like
nothing unusual was happening? Can the cylinder be manually pushed back in with the lever in any
position? You mention this is a home-built splitter - did you just get it together or has it
been working fine until now? Did the problem appear all of a sudden or gradually over time.
(Sorry for all the questions here! Just trying to help nail down exactly what is happening.)

I agree with Jim and also have suspicions that something in the valve isn't right. Obviously
you're somehow getting oil out of the neutral "loop back" gallery into the port to the base end
of the cylinder. And, at the same time it would have to be allowing oil from the rod side to
find a way out. A worn spool and/or bore could potentially cause this. Equal pressure applied
to both sides of the cylinder will cause it to extend due to the larger piston area on the base
side and if the valve was leaky enough would also allow oil to escape from the rod side back to
tank. The spool should have an extremely close fit in the bore - any amount of "wiggle" means
there is a problem.

You're post must have popped in when I was working on mine. You answered some of the questions I
was asking here.

Thanks Brendon.

It has been working fine the last year or two, neighbor borrowed it and came knocking on my door a few hours later saying he couldn't get it to retract.

I was able to push the ram back by knocking it with a sledge (held it at the head and knocked the sled/ram back. I was thinking at the time that it wasn' too hard to move, not 254 cubic inches of hyd fluid being forced back through 1/2" retun lines hard. Now I can push it back with my knee. Doesn't matter lever position.

Engine just keeps chugging like there's no load. No new noises from the valve or pump.

Unfastened rod seems most logical fit for these symptoms.... Right?

Could possibly be a badly plugged filter, or a restriction in the return line. Give us an update when you find the problem!

Mine did that once, I can't remember which
time though. I had an issue with the
adjustment on the detent valve one time that
allowed it to creep out, and a wasted cyl
seal. The detent valve might have been only
an adjustment, but it seems it had a piece
of cyl seal stuck in there??? Been too many
years ago to remember.

After thinking through it some more I'd agree that the piston coming off the rod is plausible,
especially if the problem showed up all of a sudden. This would essentially turn the double-acting
cylinder into a single-acting cylinder with the rod end port becoming the one work port. The need
for oil to exit the cylinder when extending would be eliminated and of course would make it
impossible to retract. In theory the force to extend the cylinder due to backpressure (from line
loss, filter restriction, etc) combined with valve spool leakage into both ports while in the
neutral position is the same whether or not the piston is attached to the rod - it is just the
pressure times the rod area. But, without the relatively high drag resistance of the piston seal
helping hold it in place it could extend with very little pressure.

Well I finally got around to tearing into the splitter. It was the nut that came off the rod, Piston & seals and all look great. I'll get some RED loctite on there and re-torque. Should be a simple matter of refilling and good to go!

Thanks for all the ideas guys.