Log splitter is aerating the hydraulic oil

[DLStryker]

My dad built a log splitter about 30 years ago. 8hp Briggs. Barnes 11gpm 2 stage pump. LS-3000-1 directional control valve. He only split about two cords of wood before he stopped cutting wood. I recently picked up the splitter and changed the hydraulic hoses, the fluid and the filter. This was mid summer (so, summer temperatures). The hyd oil tank is 5 gallons. Teh system if full of hyd oil and about 1 gallon of hyd oil in the tank. The top of the suction line hole in the tank is 2" above bottom of tank. Hyd oil is 3.5" above bottom of tank. Splitter worked fine. Split about 20 logs. Splitter has sit for about 2 years.

Just fired up the splitter. About 30 degrees F outside. Ram moves in and out very jerky. When ram extends and starts to split log, the ram stops. Engine does not bog down. Hyd oil in tank is aerated. A large amount of air is blowing out of the hyd tank filler pipe. I covered all suction line connections is a full surround of shaving cream. All you could see is a full covering of smooth shaving cream. I ran the ram in and out a few times. I inspected all of the shaving cream and saw zero evidence of a suction leak. I have the same test on the hyd pump shaft. Because of the set up, I was not able to do such a complete test on the shaft. I had limited access. When the shaft would spin, a small amount of the shaving cream would move away from the shaft. But, with what was there, I saw no signs of a suction leak.

Any thoughts?

Could I be getting cavitation because there is not enough oil in the hyd tank. Cold weather possibly thickening the oil and the 2 to 3 pound of pressure expected in the suction line being less that the 2 to 3 pounds. Do I need to fill the 5 gallon tank for winter temperatures? Or do you think I have a suction side air leak?

 

[cscltd]

Im not a hydraulic expert, but if your saying there is oil tank is filled 3.5” from bottom of tank and suction hose is 2” from bottom of tank, an 11 gpm pump wants more fluid than there in the tank to circulate is I think

 

[Marley5]

Sounds like the pump is starving for fluid.
Add another gallon and see what happens.

 

[DLStryker]

Im not a hydraulic expert, but if your saying there is oil tank is filled 3.5” from bottom of tank and suction hose is 2” from bottom of tank, an 11 gpm pump wants more fluid than there in the tank to circulate is I think

Tank filled to the same level worked fine two years ago in summer heat. Just above freezing here now. I am going to drain and fill the hyd fluid though. And also fill the hyd tank close to the top.

 

[Del_]

There might be an air leak on the suction side plumbing,

 

[DLStryker]

There might be an air leak on the suction side plumbing,

I had explained in my original post how I had checked for that. Not sure my method was sufficient. Could you take a read and offer your opinion on my method?

 

[Big_Eddy]

If you have a 11pm pump and a 5 gal reservoir, you will want it almost full to the top. A well sized splitter has 1 gal of reservoir for every GPM of the pump for cooling capacity and to allow air to escape from returning fluid before it gets pumped again. With less overall fluid, either thre cold fluid is just not flowing through the tank from inlet to outlet fast enough, and the pump is sucking dry, or the fluid is getting aerated and the air bubbles can’t escape through the cold fluid fast enough.

The warmer fluid in the summer will flow faster, and will shed air faster..

 

[Yarz]

The warmer fluid in the summer will flow faster, and will shed air faster..

If it worked in the summer, and nothing else has changed, I'd agree this is probably the issue. What weight oil is in there?

The top of the suction line hole in the tank is 2" above bottom of tank. Hyd oil is 3.5" above bottom of tank.

I assume that you checked this with the ram retracted, like most people would. Have you looked once the ram was extended? This would be the most oil removed from the tank, and will make the issue mentioned above worse.

 

[Sidecarflip]

In as much as it's 30 years old and hydraulic hoses degrade over time, I'd start with replacing the hydraulic hoses, especially the one on the suction side and go from there. Things do wear out, especially hoses. A suction side leak will ALWAYS cause foaming of the fluid. Always and you cannot see it, unlike the pressure side hoses. Hopefully it is charged with hydraulic fluid and not motor oil. Hydraulic fluid has specific additives to prevent degradation of components. Motor oil don't and hydraulic fluid is most times a lighter viscosity than motor oil is.

Lighter viscosity fluid flows better when cold.

 

[triptester]

Hydraulic fluid that flows well in summer does not always flow well in winter. By not filling the tank to the proper level a vortex may be forming near the suction openning because fluid is not moving fast enough from the far end of the tank ,thus allowing air to get into the flow. Fill the tank to within 1" - 1 1/2" of th top.
Also could change to ATF fluid or AW10 hydraulic fluid.