Help bleeding hydraulic system in log splitter

[ShipWreckDiver]

I've got a Troy-Bilt LS275 log splitter that's been causing me some grief for a bit. I just went over the whole Honda engine, cleaned and rebuilt the carb, adjusted the valve lash etc. Put the engine back on and changed the hydraulic fluid & filter. The engine is now working perfect again. (Worst carb I've ever had the displeasure of working with).

Despite having a considerable mechanical background, hydraulics are not my strong point. I'm certain the hydraulic system needs bleeding out but just can't figure out how to do that. Only mention I can find from Troy-Bilt's site is about extending the ram then turning the release screw counter-clockwise "as fast as I can" till the ram reverses, then back again. Problem, no mention at all of where the "release" is, what it looks like, nothing. Just nothing. I can't find anything on the machine anywhere that is labeled "release". There isn't much of anything anywhere, and labeling is practically non-existent. The directional valve is made by Energy. I've tried to get information from their site and came up dry there too. Any detailed, plain english, assistance would be greatly appreciated.

 

[homemade]

With the control lever in the extend or retract position and the engine start switch off. Pull the recoil until the ram moves. The pump should suck oil even if it’s dry. Then fire the engine and run the ram back and forth, full stroke a few times. It should self bleed.

 

[ShipWreckDiver]

With the control lever in the extend or retract position and the engine start switch off. Pull the recoil until the ram moves. The pump should suck oil even if it’s dry. Then fire the engine and run the ram back and forth, full stroke a few times. It should self bleed.

Thanks. It is pulling oil, As soon as I started it and let it warm up the ram works, it splits wood but once it contacts the piece, it stops dead & takes a ridiculously long time to build pressure and start moving into & splitting the piece. I understand that most of them have some hesitation to build pressure, but I shouldn't be able to go off and split a couple pieces by hand in the time it takes.

If this unit is self bleeding, is there an adjustment somewhere? Should I start thinking about rebuilding the pump? Should I roll it into the lake and get a real splitter? I've had this one roughly 14 years and it's never been this bad. I'm growing old waiting for this thing, it's just not productive.

 

[Jhenderson]

You need to check pressures. If you don’t have a gauge buy one. Northern Tool sells a 3,000 psi gauge for $13.99 Put the gauge on the pressure port leading to the cylinder base and hold the lever in forward. The pressure should be around 4-500 psi at first then the pump should kick down into the high pressure stage for around 2,000 psi. If not the the pump is bad. 2 stage pumps aren’t worth rebuilding. Just pull the numbers and manufacturer off it and use the Internet for a replacement. Also check the cylinder for bad packing by running the rod all the way out, then pull the hose off the far end. Put the handle in forward. If fluid shoots out the open bung on the cylinder the fluid is bypassing the piston packings and the cyl needs to be repaired.

 

[kevin j]

May be something else going on.

Gear pump systems open center are basically self purging in the main lines.
Cycling it a few times should have purged all the air from the cylinder. The only way it would need ‘bleeding’ is if the cylinder connections were on the bottom and air could trap up high. Even then, a few cycles should clear most of it out.

For future reference, cycle the cylinder a few times under no load. DON”T build up high pressure in the cylinder if there is air trapped in there. When the valve is moved to the other direction, the pressurized air acts like an accumulator and discharges the fluid in the cylinder really fast. Instead of 11 gpm or whatever, the flow rate mught be 50 or 100 gpm for a fraction of a second. That can blow the return filter or housing, oil cooler, or return line hose.

 

[Big_Eddy]

Splitter hydraulics are simple. Pump runs full speed all the time so as long as there is fluid available at the pump, it will be circulated and will push out any air in front of it.

Standard problems.
1) low fluid or collapsed suction hose = no flow.
2) failed, damaged or misadjusted second stage pressure cutoff in pump. Operates at low pressure, not at high pressure. Or very slowly all the time.
3) failed, damaged or misadjusted system relief pressure in selector valve. Low pressure in entire system.
4) Valve failure allowing bypassing at pressure. Usually affects pressure stroke, not retract, but could be both. We only care about pressure for now.
5) O'Ring failure within cylinder allowing bypassing under load.
After 14yrs of typical use / abuse, it's not uncommon for any of the above to occur.


Before cracking lines and adding a pressure gauge, try a couple things.
The obvious - check the hydraulic reservoir is full and the splitter is level or level enough that the intake has an adequate supply of oil.
Test 1 - cycle cylinder back and forth with no load several times. Cylinder should move back and forth smoothly with no jerkiness. This should purge any air from the hoses and cylinder. Horizontal is preferred - vertical will work.
Test 2 - split something easy. Kindling, birch, ash. Normally splitter should not go into second stage for an easy split. Splits normally - then pump low pressure circuit is okay. Stops moving and does not split - could be pump, valve or cylinder.
Test 3 (pump) - Extend the cylinder most of the way then push the lever to the retract detent and let the cylinder come back on its own. Does the lever pop to neutral on its own? If yes - then the pump is generating a reasonable pressure (more than the detent kickoff, typically into 2nd stage pressures). If not (i.e. stays in retract position with cylinder all the way back) - does the engine seem to load up at all, or not? a) Loads up - pump is generating pressure, but not enough to kick out. b) Not loading up - then not generating much pressure.

Now we need to play with wrenches.
Install a 3000psi pressure gauge in line between the pump and the valve.
Extend the ram all the way to the end, then disconnect the return hose (ram end of cylinder) from the the valve and direct it into a pail. Push the lever to extend and hold for a few seconds.
If the pressure gauge rises to 2000+psi and no fluid comes out the return line - you should be splitting normally.
If the gauge rises to 500-650 psi but no higher - then the pump is at fault. Try adjusting the cutoff pressure in case it's stuck or dirty. If no joy - replace.
If fluid flows out of the disconnected return line, then the cylinder is bypassing internally. Rebuild or replace.
Otherwise it's the valve. Adjust the relief lower (usually out) one full turn and check again. If the valve pressure drops, turn it back in 1 full turn and check. It should return to the starting pressure. Now turn it in until it's at 2000 psi. If adjusting the valve relief does not affect the pressure, valve is bypassing internally and needs replacing.

 

[ShipWreckDiver]

Splitter hydraulics are simple. Pump runs full speed all the time so as long as there is fluid available at the pump, it will be circulated and will push out any air in front of it.

Standard problems.
1) low fluid or collapsed suction hose = no flow.
2) failed, damaged or misadjusted second stage pressure cutoff in pump. Operates at low pressure, not at high pressure. Or very slowly all the time.
3) failed, damaged or misadjusted system relief pressure in selector valve. Low pressure in entire system.
4) Valve failure allowing bypassing at pressure. Usually affects pressure stroke, not retract, but could be both. We only care about pressure for now.
5) O'Ring failure within cylinder allowing bypassing under load.
After 14yrs of typical use / abuse, it's not uncommon for any of the above to occur.


Before cracking lines and adding a pressure gauge, try a couple things.
The obvious - check the hydraulic reservoir is full and the splitter is level or level enough that the intake has an adequate supply of oil.
Test 1 - cycle cylinder back and forth with no load several times. Cylinder should move back and forth smoothly with no jerkiness. This should purge any air from the hoses and cylinder. Horizontal is preferred - vertical will work.
Test 2 - split something easy. Kindling, birch, ash. Normally splitter should not go into second stage for an easy split. Splits normally - then pump low pressure circuit is okay. Stops moving and does not split - could be pump, valve or cylinder.
Test 3 (pump) - Extend the cylinder most of the way then push the lever to the retract detent and let the cylinder come back on its own. Does the lever pop to neutral on its own? If yes - then the pump is generating a reasonable pressure (more than the detent kickoff, typically into 2nd stage pressures). If not (i.e. stays in retract position with cylinder all the way back) - does the engine seem to load up at all, or not? a) Loads up - pump is generating pressure, but not enough to kick out. b) Not loading up - then not generating much pressure.

Now we need to play with wrenches.
Install a 3000psi pressure gauge in line between the pump and the valve.
Extend the ram all the way to the end, then disconnect the return hose (ram end of cylinder) from the the valve and direct it into a pail. Push the lever to extend and hold for a few seconds.
If the pressure gauge rises to 2000+psi and no fluid comes out the return line - you should be splitting normally.
If the gauge rises to 500-650 psi but no higher - then the pump is at fault. Try adjusting the cutoff pressure in case it's stuck or dirty. If no joy - replace.
If fluid flows out of the disconnected return line, then the cylinder is bypassing internally. Rebuild or replace.
Otherwise it's the valve. Adjust the relief lower (usually out) one full turn and check again. If the valve pressure drops, turn it back in 1 full turn and check. It should return to the starting pressure. Now turn it in until it's at 2000 psi. If adjusting the valve relief does not affect the pressure, valve is bypassing internally and needs replacing.

That's quite the concise diagnostic. And I even understood most of it. Thank you for taking the time.

The short story; I got a little desperate when I needed to be splitting and cold weather is closing in on me here so I had played with the only adjustment I could find and things got worse. So I took that cap off the direction valve and with the motor running and while cycling the ram, turned the adjustment screw in, cycled and turned in some more. I put it in pretty much as far as it would go, again, having no idea what I was actually adjusting (did I say I was desperate?) and cycled the ram a few more times. Dropped a round in and it split with a lot less hesitation. Dropped in a bigger one and it went through too. Didn't ask questions, it was functional & I went to work. So far so good, I've just been wondering how long it might last. (That prick Murphy has been around here way, way too much lately).

So from Eddy's explanation, I'm guessing this "3) failed, damaged or misadjusted system relief pressure in selector valve. Low pressure in entire system." is what I was messing with. Is this an adjustment to make up for wear on the relief valve? Since I think I may have it adjusted all the way in now, should I be looking at rebuilding or replacing this directional valve in the near future? Source for parts?

I am still curious about the pump and the ram seals, although having looked around for replacement options for the ram seals and finding a whole lot of confusion and not much else, I'm very leery of having to touch that cylinder.
The pump, so far as I can tell, has no adjustment on it. At least nothing accessible from the exterior, without removing and opening it up. Any suggestions for getting a better education about these? Being a Troy-Bilt splitter from Lowes, I'm guessing it's a pretty low end pump & maybe just ripe for replacement with something better regardless but I'm going to put this list of diagnostics on the agenda for spring, after the frenzy to get through this winter is over and see what needs to be dealt with and not.
Being terminally behind on wood for heat when winter is closing in on you is bad enough but that, along with this terminally wet weather, everything known to man going wrong and keeping me from getting things done and firewood dealers telling me they aren't selling this year cause they don't have anything dry, I've been riding the razors edge of blowing my cork for so long I feel like I've aged ten years this past month. Also can't stop thinking that after the past several months, this winter may be a winter from hell, on top of everything else.