bobcat m700 issues

[chmura]

We just bought the cat a few days ago.... here is the problem while cold everything runs perfect..... once it heats up I lose steering (1/2 hour to 1 hour) I park it and it cools off works perfect again.... the cycle is continuous Any ideas?

 

[thetool]

Perhaps your implement pump is worn out. In addition to powering the hydraulics for lift and tilt. it provides charge pressure to the hydrostats. It's still good when the oil is cold and thick, but as it warms and thins, the worn pump shows.
If the lift and tilt functions also slow down when your drive starts to act up, I'd bet that's it.
There are other things it could be, tho. I'd check charge pressure cold and hot, first.

 

[chmura]

Perhaps your implement pump is worn out. In addition to powering the hydraulics for lift and tilt. it provides charge pressure to the hydrostats. It's still good when the oil is cold and thick, but as it warms and thins, the worn pump shows.
If the lift and tilt functions also slow down when your drive starts to act up, I'd bet that's it.
There are other things it could be, tho. I'd check charge pressure cold and hot, first.

can u explain charge pressure?

 

[thetool]

can u explain charge pressure?

I've been looking at my manual. Charge pressure is the pressure of the oil that keeps the hydrostats full of oil at all times. According to my manual, this is only 45 psi for the M700. You can check it by istalling a gauge into the top of the filter housing that is attached to the hydrostatic pump. But now, since it's only 45 psi and your boom and bucket still work okay, I don't think that's your problem anyway.
You have a by-pass valve that tees off between the line to that same filter and to the vane pump suction line. I'm thinking this is the problem. The manual says to put a flow tester between the bypass valve and the vane pump inlet, and there should be no flow. Now if that filter plugs, it will by-pass and no drive. But that's a constant failure, and yours starts to fail when it warms up, so I think the by-pass valve is bad or leaking by inside.
You can take it off and inspect the seal and the seat inside. You can new parts if they're worn. When you put it back together, the arrow on the valve housing points toward the pump.
Good Luck

 

[m610]

can u explain charge pressure?

Charge pressure is measured by removing the threaded plug on the upper hydraulic filter. Do you have the 720 manual to refer to?

 

[chmura]

Charge pressure is measured by removing the threaded plug on the upper hydraulic filter. Do you have the 720 manual to refer to?

wow... Im confused.... I think Ill get a manual..... then all the help im getting will make more sense...

 

[sterlclan]

wow... Im confused.... I think Ill get a manual..... then all the help im getting will make more sense...

probably worn wear plates in the hydrostatic pump.....relatively easy repair there is a post or two here that explain it yell if you need help.....Jeff

 

[Tazza]

probably worn wear plates in the hydrostatic pump.....relatively easy repair there is a post or two here that explain it yell if you need help.....Jeff

Lift the cab, on top of the pump there should be a square block with 3 hoses on the left, remove the middle one and fitting, there should be a filter behind here. Clean or replace it, it should clear up your drive issues.
Hopefully your machine has this suction line filter fitted! Its a known issue.

 

[chmura]

Lift the cab, on top of the pump there should be a square block with 3 hoses on the left, remove the middle one and fitting, there should be a filter behind here. Clean or replace it, it should clear up your drive issues.
Hopefully your machine has this suction line filter fitted! Its a known issue.

I Gave up and took it to the dealer for an estimate...thanx for the help we'll see what they say...

 

[Tazza]

I Gave up and took it to the dealer for an estimate...thanx for the help we'll see what they say...

Let us know what they have to say.