Hello everyone,
I have been working on my neighbors JD300 T4W3D Serial # 111673T for a couple weeks trying to get it working correctly again. I will start with the series of events and then get to the current issue in case something that happens can spark an idea to some one.
Machine was running fine. Was using the backhoe to move dirt when there was a loud bang and complete loss of function. Engine stayed running but no hydraulics. found the splined shaft for the input of the hydraulic pump stripped out. Removed pump and took in for a rebuild. They were held up with parts so they gave us a spare that had been rebuild on the shelf and we installed along with a new splined coupling. Filled the fluids and machine started without any issues. High fives all around and he put the machine back to work. We were later informed that the original pump was in bad shape when they finally got to rebuilding it at the shop.
Next day I get the call that something doesn't seem right. The hoses were jumping like crazy with function. worried about blowing a hose. Came across the accumulator and unscrewed the cap over the schrader valve and found hydraulic fluid in the cap. Removed accumulator and had rebuilt and recharged and reinstalled. Jumping seems reduced and put the machine back to work.
Again issue with the machine. It is struggling to start but if you lower the bucket or backhoe it starts just fine and this is what has to be done every time you start the machine. I played with the manual destroker valve and if I turn it all the way in I loose loader function but not hoe function? this seems weird as the pump supplies pressure to both so how can it only eliminate one? should cut off both correct?
This Machine is the oldest machine I have ever worked on and I have never worked on a machine with a closed loop system like this. From what I can tell the destroker valve is not functioning properly. I am wondering how does this valve operate? is it getting some sort of external pilot pressure to activate or is it internally done in the pump? I have seen alot of threads on the destoker causing loss of pressure but only one that refers to this problem unfortunately it just goes flat without an end result. Any advice would be appreciated. I am worried operating it like this may cause pump damage.
I have been working on my neighbors JD300 T4W3D Serial # 111673T for a couple weeks trying to get it working correctly again. I will start with the series of events and then get to the current issue in case something that happens can spark an idea to some one.
Machine was running fine. Was using the backhoe to move dirt when there was a loud bang and complete loss of function. Engine stayed running but no hydraulics. found the splined shaft for the input of the hydraulic pump stripped out. Removed pump and took in for a rebuild. They were held up with parts so they gave us a spare that had been rebuild on the shelf and we installed along with a new splined coupling. Filled the fluids and machine started without any issues. High fives all around and he put the machine back to work. We were later informed that the original pump was in bad shape when they finally got to rebuilding it at the shop.
Next day I get the call that something doesn't seem right. The hoses were jumping like crazy with function. worried about blowing a hose. Came across the accumulator and unscrewed the cap over the schrader valve and found hydraulic fluid in the cap. Removed accumulator and had rebuilt and recharged and reinstalled. Jumping seems reduced and put the machine back to work.
Again issue with the machine. It is struggling to start but if you lower the bucket or backhoe it starts just fine and this is what has to be done every time you start the machine. I played with the manual destroker valve and if I turn it all the way in I loose loader function but not hoe function? this seems weird as the pump supplies pressure to both so how can it only eliminate one? should cut off both correct?
This Machine is the oldest machine I have ever worked on and I have never worked on a machine with a closed loop system like this. From what I can tell the destroker valve is not functioning properly. I am wondering how does this valve operate? is it getting some sort of external pilot pressure to activate or is it internally done in the pump? I have seen alot of threads on the destoker causing loss of pressure but only one that refers to this problem unfortunately it just goes flat without an end result. Any advice would be appreciated. I am worried operating it like this may cause pump damage.
