Hydraulics quit working after getting hot. Mostly a loss of power to the point of driving backwards to get out of the way. Help

[Xchief]

That doesn’t sound cheap. Will check the fan and change fluids and cross my fingers. Was my Dads and pretty sure he didn’t do all that was needed. Last complete Service was done by a MF dealer but is not close by. It is a 2002 and has a ton of hours and who knows about the service on this. Thanks for the info

 

[DMW]

Dealer serviced usually means it got the cheapest bulk fluid that met the absolute minimum requirements. I had to change out my first dealer service HST fluid after a year due to water contamination. Corrosion on the electrical connectors/fuses has been my biggest issue, no lube was applied to them at the factory.

 

[cdaigle430]

IM hoping its something simple instead of the spline issue.

 

[ptsg]

A spline failure would cause it to not work regardless of the temperature, so I don't think this is the issue.

 

[Dmacleo]

A spline failure would cause it to not work regardless of the temperature, so I don't think this is the issue.

That's what I was thinking. Wondering about bypass valve issue.

 

[ray66v]

Keep in mind, there are two pumps.

And, the hydraulics are aparently not working at all.

Can't completely rule out the possibility, that the HST drive pump issue may be related to the shearing of the main hydraulic pump.

 

[Dmacleo]

Keep in mind, there are two pumps.

And, the hydraulics are aparently not working at all.

Can't completely rule out the possibility, that the HST drive pump issue may be related to the shearing of the main hydraulic pump.

they are working until it gets hot...

 

[ray66v]

they are working until it gets hot...

Okay, my mistake. Didn't take the time to digest that.

This seems different than any of the other failures.

If we assume the main pump has not failed in some way, I don't know a clear path to explain an intermittent, or heat related failure like this.

I would expect the OP has considered things like: Possibly someone used an unapproved HST filter? Water in the hydraulic oil?

I think I would pull the screen to verify there is no debris, and get a good look at some of the oil.

With two people, one can hold his finger over the opening to keep all the oil from draining, after removing the screen. And another person, checks the screen and the oil.

 

[Midniteoyl]

Sounds like overheating of the oil. Don't know what the problem is but slowing down and going weak is what happened on our hydraulic CNCs when the oil overheated, usually from clogged/dirty cooling system..

 

[Dmacleo]

Again I'd take look at relief valve or pressure regulator. Whatever the valve called that you can adjust near the underside of the deck height adjust. Can't remember the nomenclature right now.