# Splitter spitting hydraulic fluid?



## Hellbent (Jan 13, 2014)

My splitter just started spitting out hydraulic fluid through the vent hole in the reservoir cap. My buddy's splitter is doing the same thing. I recently just added about 1/2 qt of hydraulic fluid to the reservoir but other than that nothing strange or out of the ordinary has happened. It has been very cold here but his was doing the same thing in August.

My only thought is I overfilled it but it seems to be leaking out more than I put in...

Thanks, Hellbent


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## dave_dj1 (Jan 13, 2014)

How long before it runs out? Hydraulic fluid will expand when hot. You probably just overfilled it. What is the air temp? I let mine idle for 15 minutes or so before I even try to move anything in the extreme cold. 
dave


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## jrider (Jan 13, 2014)

You either overfilled it or are on uneven ground.


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## Hellbent (Jan 13, 2014)

Damn, I knew it was something like that! Probably a combination of both. I usually let the engine and hydraulics warm up for probably 10 minutes. 

Thanks for putting my mind at ease! Hellbent


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## VINIFIREWOOD (Jan 13, 2014)

Extreme cold can create cavitation in the pump when the fluid is too cold and thick and basically refuses to flow. This can add a lot of air into the oil therefore causing an over full like condition. Cavitation is the pumps worst enemy.


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## greendohn (Jan 14, 2014)

VINIFIREWOOD said:


> Extreme cold can create cavitation in the pump when the fluid is too cold and thick and basically refuses to flow. This can add a lot of air into the oil therefore causing an over full like condition. Cavitation is the pumps worst enemy.



After all these years I ran in to this for the 1st time a week or so ago. I didn't know what was going on, added a splash of fluid and the pump was still making a racket. I ran the ram back and forth a for a minutes and shut it down, thinking it was the cold. In winters past I have always kept the splitter in the garage where I build a daily fire in the wood stove. This winter I have been keeping the splitter in the wood shed and the arctic blast we had was just too much, I guess. 
The old splitter developed a slow leak around the shaft this winter that will be tended to this spring. That old unit sure doesn't owe me anything, just a bad time of the year for any down time.


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## groundup (Jan 14, 2014)

Mine does the same thing occasionally.


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## timbrjackrussel (Jan 16, 2014)

What oil are you using? I use ATF and have no problems.
Always let it warm up when cold.


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## kevin j (Jan 16, 2014)

First is proper fill level and tank level on the ground not tilted. Assuming those are already ok, I think you are sucking air on the inlet.

Cavitation is when the inlet liquid turns to vapor, then back to liquid when compressed. It is dangerous to the pump so poster above on the right track but for different reasons. 

I think what you are seeing is 'aeration' or sucking in air into the fluid.
Cavitation won't increase tank volume. Aeration will big time. and also damage pump.
Cold thick oil takes more inlet 'vacuum' to move into the pump at a given flow rate. That high 'vacuum' or low absolute pressure can cause cavitation, but it can also cause leaks on the inlet line, hose, ports, or shaft seal, which leads to aeration by sucking in outside air even if the leak doesn't leak oil out when parked. Suction strainers/filters make things worse due to restriction if not oversized properly.

Releasing air takes a long time, especially cold oil. Check next day and see if level is back down. Then check carefully for leaks where air can go into the suction line. Pack some grease around the pump shaft seal when starting up and see if it changes anything temporarily. i.e. takes much longer to aerate.


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## Marrowstone (Jun 10, 2020)

I just had my splitter spit out hydraulic fluid out of the cap for the first time. Been using it for 20 years on and off and no problem. It wasn’t a hot day (60 degrees F.), the terrain was level, the amount of fluid in the tank was fine. i Was splitting madrona wood which can be tough but wasn’t overloaded. Any suggestions?


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## JeffHK454 (Jun 10, 2020)

Marrowstone said:


> I just had my splitter spit out hydraulic fluid out of the cap for the first time. Been using it for 20 years on and off and no problem. It wasn’t a hot day (60 degrees F.), the terrain was level, the amount of fluid in the tank was fine. i Was splitting madrona wood which can be tough but wasn’t overloaded. Any suggestions?


Is the oil in reservoir frothy? Might have a leak in the suction side letting it aerate the oil.


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## Marrowstone (Jun 10, 2020)

JeffHK454 said:


> Is the oil in reservoir frothy? Might have a leak in the suction side letting it aerate the oil.


No, it wasn’t frothy, it was quite clear. But one of hoses might have a leak in it. I think they are due to be changed anyway. Thanks for the post.


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## kevin j (Jun 10, 2020)

wow. I wrote that post above 6 1/2 years ago. Time flies. and life changes a lot


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