B7500 Steering Problems

waxahachie · Jul 19, 2010

I have a Hydrostatic drive tractor. Never any problems until this year (6yrs.ok)
When it is hot outside, around 100 deg., and I am mowing at 540pto w/2500 rpm's the steering starts to have a little bit of hesitation or scratchiness in when turning. The engine does not run hot, but obviously the hydraulic fluid does. Kubota does not have a separate oil cooler for this fluid as many others do. If I let the tractor idle for about fifteen minutes, this problem will go away for a while. Does anyone have an idea of the problem. If it is below 90 deg outside this never happens. Does anyone know if it is possible to install an auxillary oil cooler.
Any replies are greatly appreciated.

KennyV · Jul 19, 2010

Your hydraulic system will typically run 100 degrees hotter than ambient temp... so at 90 degrees your fluid is most likely 190 or more...
Most hydraulic fluid is intended to run at less than 180 degrees...
So there are going to be times that you are at or beyond the limits.

Your best solution is a full synthetic fluid that will function at extremes.
There are multiviscosity fluids that are better than straight weight but still not as good with dealing with heat.

Adding a cooler to the hydraulic system that has the 3pt as the final system in the loop is not going to be simple or cheap...

If your problem is actually heat related, switch to a real synthetic hydraulic trans fluid. Every hot summer I am tempted to do just that... My L4200 has a cab so I also have an air conditioner that adds heat to my total system, got to get rid of heat... KennyV