Skid Loader won't move

[GLwelder]

Hello Guys,

I posted this at a skid loader site but I know there are some excellent mechanics here:

I have an older (1986-7) NH L455. I have just in the last month replaced a bunch of o-rings on the control valve and every fitting I could get a wrench on to fix a hydraulic leak. The machine was running sweet w/o any leaks for about a month when it stopped this morning. I was starting to move some rottomill and slammed pretty hard into the pile when the hydrostatic charge warning came on and nothing moved. The fluid level is ok and the diesel runs fine but nothing moves and the pumps are whining like crazy. I didn't run it long, I know its not good for the pumps.

Thanks for any feedback, George

[metalmeltr]

well if the valves are ok it has to be either the pump or the hydraulic motor if you know what the out put of the pump is try putting in a flow meter to test it

[Atomik777]

I have limited knowledge in repairing hydrostatic drive, but plenty in destroying them. Those pumps are sensitive to contaminants and dirt and need decent amounts of oil changes. And not doing so can render the pumps pretty much useless. the extra heat can warp the internals causing a disturbing whine.

[wrenchin80]

You might want to check the pump coupler, it could be stripped out. You could remove the outlet hose from the gear pump, turn the engine over and see if any flow is coming out. But better put a couple drain pans down first.

[duaneb55]

The "hydrostatic charge warning" means no charge pressure (makes the main pump do its thing) and a hydraulic pump whinning usually means cavitation (oil starvation). Check for a closed charge pump suction isolation valve at the reservoir, rag in the tank plugging the charge pump suction port or a plugged charge pump suction filter if so equipped.

[farmersamm]

Duane, what do those hydrostatic motors take in GPM. My swathers take a huge amount of oil to keep the pump from running dry, and I'll bet because their old tech, the GPM is low in comparison

[farmersamm]

I have 20-30 gal resivoirs in the tongue of the machine to feed the pump

[farmersamm]

Just took a gander at the book. 21.5GPM with a 24gal resivoir

20-20 sae motor oil. Go figure. But I can still get it from the local supplier. Quaker State in metal cans Post a pic later

[farmersamm]

A Blast From the Past:D:D:D

I buy this stuff by the case, and the guy has a couple of pallets of it. It's all about old equipment, and the suppliers that know we still run it.:laugh::laugh:

The ol' guy buys NOS, and idiots like me chase him down to buy it:D

[GLwelder]

Hello guys, thanks for the feedback. I think wrenchin80 might be right. I went to the NH dealer and the service manager was pretty certain that the spline connecting the motor to the pumps is bad, possibaly also the shaft out of the pump.

The good news is the parts aren't very expensive and changing them is easy.
The bad news is getting to the shaft requires pulling the engine or the pumps, ugggggggh! I will pull the pumps from the top, although the service manager said he would pull the engine.

I don't think I'll get to it this weekend, I'll keep you posted.