Mustang 930A right side will not move forward

[BellH]

I can make the right side move in reverse but not forward. It seems a little weak in reverse as well. Any ideas? It leaks oil and when I top it off it moves forward but not as strong as the other side.

 

[Tazza]

I'd suspect a shuttle valve or seal in the motor is bad, if you swap motors from side to side to see if the issue moves, you will know for sure.
Seals do go bad in the motors allowing fluid to by-pass the internals of the motor and goes right back to the pump.

 

[BellH]

I'd suspect a shuttle valve or seal in the motor is bad, if you swap motors from side to side to see if the issue moves, you will know for sure.
Seals do go bad in the motors allowing fluid to by-pass the internals of the motor and goes right back to the pump.

I saw a video on youtube that said to disconnect the hoses and install plugs on the ends. Then push the lever forward , it should cause the engine to start to stall as if the wheels were locked up if pressure is getting to the motor. If it doesn't then the problem is the pump. Can you fill me in more on what a shuttle valve is?

 

[Tazza]

I saw a video on youtube that said to disconnect the hoses and install plugs on the ends. Then push the lever forward , it should cause the engine to start to stall as if the wheels were locked up if pressure is getting to the motor. If it doesn't then the problem is the pump. Can you fill me in more on what a shuttle valve is?

Capping the lines will test that the pump is pumping, but without a gauge, you won't know the pressure.
The way i understand a shuttle valve is that it allows case drain fluid out of the motor when the motor runs forward and backward. Esseniall, if it gets stuck, it can allow fluid from one high pressure line straight to the case drain line without doing work.