# 8HP 24Ton Wood Splitter Problem



## seeyal8r (Jan 20, 2011)

I've been burning wood for some time now using it to heat my home. I cut Oak, Blackjack, Hickory, and Pecan to burn in my fireplace and usually heat it with around 5 ricks a year using a Regency wood stove.

So far I've always split my wood by maul but after hearing from folks owning hydraulic splitters I bought a used wood splitter claimed to be 8 years old but rarely used. After a little tinkering I got the motor running great and set my first log to Split. It was a 18" diameter freshly cut oak that the splitter made quick work of. After splitting 3 or 4 logs in this fashion I was thoroughly impressed with the power and ease of the splitter however it seemed to be losing strength. When the wedge contacts the wood I can audibly hear the gas motor working under the pressure but the wedge doesn't seem to be pressing very hard. I became discouraged and shut the unit down for lunch. Upon returning after a bit the wood splitter began splitting with ease again before eventually loosing power. The only thing that changes from the initial start to 10 minutes into the splitting session is the temperature of the hydraulic fluid which is warm in the hoses but obviously more viscous than at initial start.

My question is this... I'm assuming there is a hydraulic leak in the controller or the pump is going bad but how would I know which one to start with? My thoughts are that as the hydraulic fluid warms up it is either slipping through the controller (no leaks detected) or the pump is having problems moving it since its more fluid.

Any help would be appreciated as this is my first hydraulic endeavor.

(just for info I left the motor running with the controller in neutral for 30 minutes. The splitter then couldn't split a branch 4" in diameter and 18" long so that should give you some idea of the pressure loss)


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## seeyal8r (Jan 20, 2011)

Thanks for moving this to the proper forum. I apologize for my ineptitude. I did also want to mention that I bought the splitter for $500 and after replacing gas lines and cleaning the carb, needles, float, pump, and replacing the filter I'm at a total of $519 invested. Pretty sure its a $1500 splitter if I can get the hydraulics figured out.


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## RobC (Jan 20, 2011)

Have you checked the Hydraulic fluid ? Two things, replace the filter & there should be a drain plug on the bottom of hydraulic tank. Tilt so plug is lowest and wait over night. Then remove plug and see if any water or crud comes out. Almost sounds like something gets sucked onto filter and clogs the works.


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## bogydave (Jan 21, 2011)

It may be the oil in it is not "hydraulic" oil. Some oils when they get hot get too viscous (thin)
& an older pump, valve, pressure control,  or ram may let too much bypass due to wear. 
If the engine is not lugging down, 1. the may be the oil is  bad, 2 the pump is worn, 3 the oil is getting too thin & bypassing through some worn part.
4 the pressure relief valve in the control valve or the pump is weak or leaking by.
Since it works when cold, the viscosity of the oil  get less when it heats up, it could be a combination of issues.
Got any pressure gauges you could use to track the pressure thru the system to see where it dropping off?

My first would be the oil, (drain tank & hoses, clean the tank, new hydraulic oil & filter) then suspect the pump or the control valve next.
Pump pressure  (install a high pressure gauge on the discharge side of the pump) when it starts to fail is a good place to start. (record operating cold/hot pressures)
Another way to check pressures is to install some valves, closing the valves (close it slowly) along the system should stop the pump or really lug the motor (the pump may/should have an internal pressure bypass) but 
you would notice a difference in sound & rpm.

The coupler from the motor to the pump can slip but, that's not  oil temperature sensitive .

Good luck


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## triptester (Jan 21, 2011)

The 2-stage pumps used for log splitters may fail completely but rarely wear out. Check the suction hose as it warms up it may be getting soft and collapsing starving the pump. Also check the hydraulic fluid to see if it looks foamy when warm this is a sign of an air leak in the suction line.


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## seeyal8r (Jan 21, 2011)

I will change the hydraulic fluid and filter since that is the easiest option at the moment. I don't have a pressure gauge but will start that route next. I'll keep you posted. Thanks.


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## tiber (Jan 21, 2011)

Seconded on changing the fluid. What typically happens on "hydraulic fluid" is that air is absorbed into the fluid. The air is invisible, the bubbles are too tiny to see and they hang out in suspension. When you use the pump, you're heating it up. The oil may not expand much, but the air expands a lot and it is very compressable. It sounds like, if it's been sitting for 15+ years, it's got a lot of air in suspension. The fluid doesn't turn dark per se, but it will become clouded. If the fluid isn't deliciously transparent (think oil like you'd buy at the supermarket or fresh engine oil), then it's probably got quite a bit of air in it.


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## seeyal8r (Nov 17, 2011)

I replaced the fluid but that didn't help. I still don't think its operating as it should but its much much better.


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## Jags (Nov 17, 2011)

bogydave said:
			
		

> Another way to check pressures is to install some valves, closing the valves (close it slowly) along the system should stop the pump or really lug the motor (the pump may/should have an internal pressure bypass) but



I would not recommend doing this.  On splitters, most relief valves are located in the directional valve.  If a valve is put inline before the relief valve and closed- catastrophic failure is probably on the menu. This could be done "After" the relief valve, but not before.


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## Jags (Nov 17, 2011)

seeyal8r said:
			
		

> I still don't think its operating as it should but its much much better.



Explain??


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## wkpoor (Nov 18, 2011)

tiber said:
			
		

> Seconded on changing the fluid. What typically happens on "hydraulic fluid" is that air is absorbed into the fluid. The air is invisible, the bubbles are too tiny to see and they hang out in suspension. When you use the pump, you're heating it up. The oil may not expand much, but the air expands a lot and it is very compressable. It sounds like, if it's been sitting for 15+ years, it's got a lot of air in suspension. The fluid doesn't turn dark per se, but it will become clouded. If the fluid isn't deliciously transparent (think oil like you'd buy at the supermarket or fresh engine oil), then it's probably got quite a bit of air in it.


Totally wrong! Any oil, hydraulic automotive, or transmission will work fine. I have used 5w30 in many hydraulic systems without fail. Sure oil sold for hydraulic systems does have additives to improve preformance in hydraulics appilcations but in something like a log splitter anything will work. That dude wasted his money on an oil change.


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## MasterMech (Nov 18, 2011)

Jags said:
			
		

> bogydave said:
> 
> 
> 
> ...



No valves necessary. On an open center system you should be able to install your pressure guage at the appropriate location and test relief pressure at the end of the cylinder's stroke.  If the engine IS bogging significantly when the wedge touches the log or the cylinder is at the end of it's stroke, then I would suspect restriction on the suction side of the pump.  Should also cause the wedge to move much slower than normal as system flow will be greatest with no load on the cylinder.

Valves would only be required if trying to isolate the problem on the pressure side of the circuit.  With such a simple circuit, diagnostics are very simple and most problems could be licked without installing isolation valves.


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## velvetfoot (Nov 18, 2011)

The air vent is open?


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## MasterMech (Nov 18, 2011)

velvetfoot said:
			
		

> The air vent is open?


 Hmm. Most of these have a breather type cap that would have to be plugged but good to overcome the vacuum a 8hp engine with a gear pump can create.  Doesn't cost anything to check out tho.


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## seeyal8r (Dec 28, 2011)

Finally got around to working on the splitter over christmas break. replaced the hydraulic lines and now I'm back in business. All I can figure is that whichever hose was being placed under a vaccume was leaking air which was causing the loss in power. Ran the splitter for a while and it seems to be back in great shape. Also learned that it has to be sitting pretty level. During one use it quit and wouldn't start. After cool down it started then died after a few minutes. Apparently there is a low oil sensor that was losing oil when it ran but allowed it to start after all the oil had drained back down. It wasn't really that low but the unlevel ground wasn't helping. After moving it around I found that the vent on the hydraulic fluid couldn't be facing down either or it would leak hydraulic fluid down after it was warmed up and thoroughly expanded from the heat.

Thanks for all the help.


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