Troybilt L27 Stalling at Full Extension & Retraction

[g00fy]

Hey guys first post here, found you guys while googling issues with my stepfathers log splitter, got lots of results but no definitive answer to the problem i'm having.

It's a 2012 Troybilt L27 log splitter with a honda GCV160 motor. The motor runs great, starts up first pull, runs strong and smooth. The thing splits wood just fine, the problem is when it gets to full extension, it stalls out instantly, doesn't even have a chance to bog down, just stops dead, same goes for if you happened to hold the lever on return instead of letting the detent do it's thing.

We had an acquaintance who splits tons of wood take a look at it, he felt the control valve was shot, so we replaced the control valve with a brand new MTD replacement valve, problem still persists.

I had read in a few places that could be a dirty / clogged carb, but it runs so good and it splits just fine, it just can't handle the load when the cylinder maxes out. I read that power washers have an "unloader valve" that keeps them from stalling when you're not actually letting the water flow, is there something similar on my log splitter? If so where is it? Is it something inside the pump? Any help would be greatly appreciated. Thanks

 

[triptester]

The valve has an adjustable relief which may be set to high and needs to be lowered. Without a pressure guage you will only be able to change the setting by feel.
Although the engine may seem to be running fine it may be getting a little weak.
I believe this is the same valve as on your splitter.
The adjustment screw is item #12 in the assembly drawing.

http://www.energymfg.com/pdf/17498X.pdf

 

[farmer steve]

Hey guys first post here, found you guys while googling issues with my stepfathers log splitter, got lots of results but no definitive answer to the problem i'm having.

It's a 2012 Troybilt L27 log splitter with a honda GCV160 motor. The motor runs great, starts up first pull, runs strong and smooth. The thing splits wood just fine, the problem is when it gets to full extension, it stalls out instantly, doesn't even have a chance to bog down, just stops dead, same goes for if you happened to hold the lever on return instead of letting the detent do it's thing.

We had an acquaintance who splits tons of wood take a look at it, he felt the control valve was shot, so we replaced the control valve with a brand new MTD replacement valve, problem still persists.

I had read in a few places that could be a dirty / clogged carb, but it runs so good and it splits just fine, it just can't handle the load when the cylinder maxes out. I read that power washers have an "unloader valve" that keeps them from stalling when you're not actually letting the water flow, is there something similar on my log splitter? If so where is it? Is it something inside the pump? Any help would be greatly appreciated. Thanks

welcome to AS @gOOfy. i have the same splitter. try pulling the bowl off under the carb. it can get dirt/water in it and affect performance. i split hundreds of cords with mine and did need to replace the pump just this past year. mine is around 15 years old. how does it run if you let the detent do it's job? some of the experts will be along shortly. i'm just a firewood hack.

 

[Big_Eddy]

Most Likely
The relief in the valve is not operating and therefore when you hit either end of the stroke, the pump load exceeds the engine output and stalls it.
You NEED to get it fixed asap. With a non-operational relief, pressures in your system can exceed the ratings of the hoses, valve and cylinder seals.

Confirm your valve make and model to find the correct adjustment method to adjust the relief pressure. Lower the pressure substantially. Count the turns when doing it. If the relief now works (albeit at a lower pressure), then turn it back in the same number of turns and test again. If it's working now, it was probably dirt or similar in the relief valve and you should be okay.

If not - either tear down and rebuild the valve or replace it - depending on your capabilities. Any splitter valve rated for the GPM of your pump should be suitable. If you do replace it - check the factory setting of the relief valve. It may need to be adjusted to match your engine / pump combination.

Alternate
There is another possibility. It could be that your 2 stage pump is not switching to low speed mode. In that case - even with a properly set relief in the valve, the engine will still stall.
Have you noticed the speed "stepping down" while splitting tough pieces? If not - then I'd be looking at the pump. Similar process - find the manual for your pump, figure out how to reduce the "step down" pressure setting, adjust it way down, test, back up and retest. If still no step-down, then replace the pump.

 

[g00fy]

The valve has an adjustable relief which may be set to high and needs to be lowered. Without a pressure guage you will only be able to change the setting by feel.
Although the engine may seem to be running fine it may be getting a little weak.
I believe this is the same valve as on your splitter.
The adjustment screw is item #12 in the assembly drawing.

http://www.energymfg.com/pdf/17498X.pdf

Thanks for the valve Breakdown, I checked it out, I see where the relief screw is, but i'm hesitant to mess with it though since I just put a brand new MTD valve in which should have the pressure correctly set and i'm still having the exact same issues.

Most Likely
The relief in the valve is not operating and therefore when you hit either end of the stroke, the pump load exceeds the engine output and stalls it.
You NEED to get it fixed asap. With a non-operational relief, pressures in your system can exceed the ratings of the hoses, valve and cylinder seals.

Confirm your valve make and model to find the correct adjustment method to adjust the relief pressure. Lower the pressure substantially. Count the turns when doing it. If the relief now works (albeit at a lower pressure), then turn it back in the same number of turns and test again. If it's working now, it was probably dirt or similar in the relief valve and you should be okay.

If not - either tear down and rebuild the valve or replace it - depending on your capabilities. Any splitter valve rated for the GPM of your pump should be suitable. If you do replace it - check the factory setting of the relief valve. It may need to be adjusted to match your engine / pump combination.

Alternate
There is another possibility. It could be that your 2 stage pump is not switching to low speed mode. In that case - even with a properly set relief in the valve, the engine will still stall.
Have you noticed the speed "stepping down" while splitting tough pieces? If not - then I'd be looking at the pump. Similar process - find the manual for your pump, figure out how to reduce the "step down" pressure setting, adjust it way down, test, back up and retest. If no step-down, then replace the pump.

I put a brand new control valve in, still have the same problem so i'm certain it's not the relief valve that's inside the control valve, I'm leaning toward a possible issue with the pump, maybe it's not kicking down? I don't know even know if it's a 2 stage pump, I can't find any detailed specs on it beyond that's it's an MTD replacement gear motor #918-04127.

welcome to AS @gOOfy. i have the same splitter. try pulling the bowl off under the carb. it can get dirt/water in it and affect performance. i split hundreds of cords with mine and did need to replace the pump just this past year. mine is around 15 years old. how does it run if you let the detent do it's job? some of the experts will be along shortly. i'm just a firewood hack.

Pulling the bowl is going to be my next course of action, just as a test though after putting the new valve in, I put a piece of wood in sideways to really load up the motor before full extension, and it went pretty far before it finally started dogging the motor, and it did stall when i went to back it out, so not sure if it stalled cause it didn't have enough fuel or it stalled because the pump motor didn't kick down to low range.

 

[triptester]

The pump is definitely a 2-stage pump. The movement of the wedge will slow down noticeably when it switches stages. If it splits wood and you notice a change in wedge speed on tough wood, then the relief setting needs to be adjusted in the valve. Turn it counter-clockwise 1/4 turn at a time until it bogs the engine but doesn't completely stall it. Note how far you backed off the adjustment if you want to return to the original setting.

 

[g00fy]

The pump is definitely a 2-stage pump. The movement of the wedge will slow down noticeably when it switches stages. If it splits wood and you notice a change in wedge speed on tough wood, then the relief setting needs to be adjusted in the valve. Turn it counter-clockwise 1/4 turn at a time until it bogs the engine but doesn't completely stall it. Note how far you backed off the adjustment if you want to return to the original setting.

If it's definitely a 2 stage pump, then it's not kicking down, it just goes the same speed until it starts bogging and eventually stalls

 

[Big_Eddy]

On most 2 stage pumps, the kick down pressure is adjustable. Here's a link to the manual for a concentric pump. Other models will be similar http://www.northerntool.com/images/downloads/manuals/1053.pdf.

The Concentric adjustment instructions are below -
3. The unloading valve is adjustable up to 600 PSI by turning
the adjusting screw clockwise.
Pressure gauge required when adjusting unload valve.
NOTE: Increasing the unloading valve pressure will require
increasing the pump drive horsepower. Factory preset, with a
400-900 PSI adjustment range. Maximum recommended loading
for 3 HP electric motors and 5 HP engines is 550 PSI

As stated - the speed change will be noticeable when the pump kicks down. Typically down to ~ 1/3rd the speed. If you're not seeing it, it's not happening.

I would back off the adjustment substantially (as much as possible) and give it another go. If it's just dirt, crud or a stuck ball, that might be all it takes. Count turns so you can put it back where it was after. If the pump still doesn't kick down, then its tear down or replacement time.

 

[g00fy]

On most 2 stage pumps, the kick down pressure is adjustable. Here's a link to the manual for a concentric pump. Other models will be similar http://www.northerntool.com/images/downloads/manuals/1053.pdf.

The Concentric adjustment instructions are below -
3. The unloading valve is adjustable up to 600 PSI by turning
the adjusting screw clockwise.
Pressure gauge required when adjusting unload valve.
NOTE: Increasing the unloading valve pressure will require
increasing the pump drive horsepower. Factory preset, with a
400-900 PSI adjustment range. Maximum recommended loading
for 3 HP electric motors and 5 HP engines is 550 PSI

As stated - the speed change will be noticeable when the pump kicks down. Typically down to ~ 1/3rd the speed. If you're not seeing it, it's not happening.

I would back off the adjustment substantially (as much as possible) and give it another go. If it's just dirt, crud or a stuck ball, that might be all it takes. Count turns so you can put it back where it was after. If the pump still doesn't kick down, then its tear down or replacement time.

Eddy, Thank you for this info, this is exactly what i needed to see, now that i know where the unloader valve is, and that this is a 2 stage pump, i'm 90% sure this is where the problem is. I'm going to try backing out the screw as much as possible, testing the splitter again to see if it now kicks down, if it doesn't, then i'll look to tear it down & freshen it up or just replace it, if it does kick down, i'll return it to stock and keep an eye on it.

 

[Big_Eddy]

G00fy - remember your obligation to future visitors. If our inputs help solve your problem, come back and post an update (including pictures - we like pictures) describing what you did and confirming that the problem has been resolved. Future visitors will thank you.

 

[g00fy]

G00fy - remember your obligation to future visitors. If our inputs help solve your problem, come back and post an update (including pictures - we like pictures) describing what you did and confirming that the problem has been resolved. Future visitors will thank you.

I'll definitely be back to post my results, and possibly pictures, I'm on a lot of automotive forums and it drives me crazy when people get the info they need then abandon the thread without posting up what the successful resolution was.

 

[turnkey4099]

I'll definitely be back to post my results, and possibly pictures, I'm on a lot of automotive forums and it drives me crazy when people get the info they need then abandon the thread without posting up what the successful resolution was.

Thanks in advance. I have the same splitter but haven't yet (know wood) had that problem. Yes I most assuredly is a 2 stage pump, mine works fine.

Question for the audience. What happens if the the wedge just cannot move, i.e., cross grain, knot, something? I have never run into it.

 

[triptester]

If the wedge stops moving entirely on a piece of tough wood the relief valve may be opening or the cylinder seals may be going bad. A pressure gauge on the system would help determine the problem.

 

[g00fy]

Ok, so Positive progress, I went ahead and found the unloader adjustment screw. I marked it with a silver sharpie so i could count the rotations, it seemed to have been cranked in to the max from the factory, I backed it out 6 turns and the screw just about fell out and it started leaking hydraulic oil. Then i cranked it back in about 1 turn to keep the screw from falling out and the oil from leaking everywhere, and yes, it made a difference the wedge moved very slow compared to usual. So I cranked it back to where it originally was, and the problem came right back, the second the wedge hits max extension it stalled. I then backed the screw out 1 turn, tried it again, it got better, it wasn't an instant stall anymore but it was still pretty fast, I backed it out another 1/2 turn and that seems to be alright, you really gotta hold it at max extension for a couple seconds before it totally bogs out and stalls. During normal splitting this should be plenty of time react and release the lever should I or my stepdad have to push the wedge to max extension to get through a stubborn piece of wood.

There wasn't much to take pictures of, it's pretty straight forward, I found the screw, took the cap off with a socket, and used a large flat head screwdriver to adjust it:

 

[Big_Eddy]

G00fy
Testing at full extension of the cylinder isn't going to confirm whether the pump is stepping down or not. At full extension - even if the pump does step down, there is nowhere more for the cylinder to go and you won't see it. You need to repeat the test - see below.

Some facts about the L27
Engine - GCV160 (4.4HP)
4.5" cylinder
2 stage pump - and no-where can I find out what it's output is - but assuming that Troy Bilt picked an appropriate pump - it's likely an 8GPM / 2GPM pump which would normally require ~5HP. (Pairing a 4.4HP engine with a 4.5" cylinder stretches my definition of appropriate. Cycle time must be nearly 20 seconds)

There are 2 relief pressures in the splitter system.
1) Pump Relief pressure. Usually about 500-600 psi. This is the pressure at which the high volume section of the pump is disabled
2) Control Valve Relief pressure. Typically 2000-2500psi. This is the pressure at which fluid bypasses the valve and goes back to tank

Normal Operation
Log on splitter, ram fully retracted. It only takes a small amount of force to move the ram towards the log so pressure in the system is low (100psi +/-) and your pump runs at ~8gpm
As soon as the ram hits the log, the force needed to move the wedge forward (jam the wedge into the log) increases, so system pressure does too. If its a tough log, and the pressure exceeds the pump relief pressure, then the pump kicks down to low speed (2gpm) and the wedge keeps advancing.
If the log is super nasty, or you hold the lever forward with the wedge at the end of it's travel, the wedge can't advance - so the pressure will rise until it exceeds the Valve Relief pressure, at which time the relief valve opens, allowing the fluid to bypass back to the tank. At no time should the engine stall.

Repeat your test with a tough log on the splitter.
Get a big solid piece of hardwood and set it crosswise on the splitter. We are expecting the cylinder to advance quickly until it hits the log, then slow down but keep advancing into the log. That's the step down. If it doesn't slow down and stalls, then the second stage is not kicking in. If it slows down and only stalls when it hits the end of the stroke - then it's the valve relief not opening.

The GCV160 is a little undersized for a standard 8/2 pump, so it wouldn't surprise me if the valve relief pressure on your new valve needs to be adjusted lower than the factory default.

 

[turnkey4099]

G00fy
Testing at full extension of the cylinder isn't going to confirm whether the pump is stepping down or not. At full extension - even if the pump does step down, there is nowhere more for the cylinder to go and you won't see it. You need to repeat the test - see below.

Some facts about the L27
Engine - GCV160 (4.4HP)
4.5" cylinder

There are 2 relief pressures in the splitter system.
1) Pump Relief pressure. Usually about 500-600 psi. This is the pressure at which the high volume section of the pump is disabled
2) Control Valve Relief pressure. Typically 2000-2500psi. This is the pressure at which fluid bypasses the valve and goes back to tank

Thanks for that! I have always wondered jusdt how a 2-stage works. That made it clear.

 

[triptester]

I would like to make one correction on the 2-stage pump. The pump is actually 2 pumps in one body, an 11 gpm pump consists of approximately a 8 gpm and a 3 gpm section. Both send fluid to the system until the kick down pressure is reached then the larger section (8) by-passes leaving only the small section to build pressure. When pressure drops below the by-pass setting the large section kicks back in.

 

[Big_Eddy]

Exactly right. 2 stage pumps are really pumps in one. At low pressures both sections are in use. When the system pressure hits the set point the high volume portion of the pump is disabled and only the low volume section operates. That way the pump can achieve the higher pressure needed to split the log without overloading the engine.

These pumps are fixed displacement pumps, meaning that the same amount of fluid is moved for each revolution of the pump. Pump flows are rated at 3600rpm, the full throttle operating speed of a typical gas engine.

Real life example of an 8GPM/2GPM pump. (Dynamic GP-CBN-080)
The low volume section moves 0.130 cu in per rev and the high volume section ADDs 0.385 cu in per revolution for a total output of 0.515 cu in per revolution in low pressure mode. Above the pump relief pressure, only the low volume section is used, for an output of 0.130 cu in per rev.

Here's the conversion to GPM
0.515 cu in/rev x 3600 rpm / 231 cu in /gal = 8 gpm
0.130 cu in/rev x 3600 rpm / 231 cu in /gal = 2 gpm

HP required
HP x efficiency = Pressure x GPM / 1714 Efficiency for a gear pump is typically 85%

High flow / low pressure mode (Actual Pressure < kick down pressure @600psi)
HP x 0.85 = 600 x 8 / 1714
HP = 3.29 HP

Low Volume / High Pressure mode (Kick down pressure< Actual Pressure < Valve Relief Pressure at 2250 psi)
HP x 0.85 = 2250 x 2 /1714
HP = 3.1 HP

Assuming typical kick down and relief pressures as above - a properly functioning 4.4HP engine should not be having stalling problems. You are running it at full throttle - correct?????