Backhoe 300b hydraulic problem

[allis chalmers hd6]

I just got a 300b. When it was running it had the sound like a hydraulic valve was sticking. I narrowed it down to this block on the right side of the trans. I thought it was the preasure relief, but from what I've read its not. I have messed with it for a week and now the hoe doesn't work. I know alot about open systems with gear pumps, but this is a new animal to me. If you can at least tell me how the system works it would help. Thanks Jim:confused

 

[Transit]

The BLOCK is most likely the priority valve. The pump feeds the valve and splits into two outputs. One output goes to the steering motor and the other goes to the rest of the tractor. What did you do to mess with it?

 

[allis chalmers hd6]

It looked like it was apart before. There is a dowel pin that was in a way that the spool would not come all the way forward. There are holes in it that line up so I put it through them Knowing it wouldn't move, But I thought it would make some difference. thats when I got hoe not front. them I put it back the way it was and now I have front and no hoe.

 

[jd110]

Is this the valve you were messing with? It would be unusual for this valve to be the cause of a noise. As transit said, it is a priority valve. Was everything working ok other than the noise? You may have a high pressure leak in the steering that could cause a hissing noise from this valve.

 

[allis chalmers hd6]

I think that is the valve, but mine doesn't have the #21 tube. everything worked before, but I had the hiss sound, the motor went to a low idle after 30 seconds, it didn't seem to have the hydra. power it should, and it would stop moving(forward) when I moved the front bucket.

 

[Barry Bowen]

If you have a high pressure leak, some of them can be pretty easy to find. Where ever the leak is, it will heat up relatively quickly. I have a 301A that had a leak in the power steering. I started the tractor from cold and just kept watching and touching to see where it warmed up. Found the bad valve that way. If you have a high pressure leak, you may find it this way.

 

[allis chalmers hd6]

Thanks Barry I'll try that. The noise seemed to be comming from that block on the side of the trans. If there were a leak somewhere else would it make that relief hiss there?

 

[allis chalmers hd6]

Does the 300b have a rotory piston pump like so many other john deere's

 

[Tx Jim]

Does the 300b have a rotory piston pump like so many other john deere's

Yes it has a closed-center piston pump. As already stated your tractor more than likely has a high pressure internal leak. The loader/BH control valves or steering valve are a good suspect. Will tractor move fwd/rearward correctly?