TC35DA won't move

[housemasters]

Just changed the hydraulic and hydrostatic filters and now have air in the fluid and the tractor won't move. Oil is full and I have worked the hydraulics back and forth, bled some air out by the filter and it will move a little way (100 feet or so) and then the air comes back. Can someone tell me how to get the air out particularly for this model?

 

[jinman]

Just changed the hydraulic and hydrostatic filters and now have air in the fluid and the tractor won't move. Oil is full and I have worked the hydraulics back and forth, bled some air out by the filter and it will move a little way (100 feet or so) and then the air comes back. Can someone tell me how to get the air out particularly for this model?

What do you mean by "worked the hydraulics back and forth."? Do you have a FEL that's working normally? Does the 3PH work normally? If those things work normally, you can rule out the normal hydraulic pump. If the only problem is the HST transmission won't work, then I would remove the HST filter, fill it with fluid, and reassemble it. It sounds like you have an air bubble in the HST charge pump circuit. If the filter is crossthreaded or not tight, you might also be pulling air there.

If your 3PH and FEL work normally, the big hydraulic filter is not the problem.

 

[housemasters]

Jinman,

Yes, my FEL and 3PH work...I know its not the hydraulic pump. I did remove the hydrostatic filer and filled it up with oil. I also checked all the lines I can see with soapy water to check for leaks and found nothing. I took off on off the lines on the oil cooler rad and I don't think I have any flow through the radiator, but I'm not sure if the oil needs to be hot first to circulate? If I crack the banjo bolt on top of the hydro filter I get lots of air coming out with some oil. When I do that for a while it will then move for a minute and then the problem starts over. Got to be something I'm missing...dealer is no help really.

 

[jinman]

Yes, my FEL and 3PH work...I know its not the hydraulic pump. I did remove the hydrostatic filer and filled it up with oil. I also checked all the lines I can see with soapy water to check for leaks and found nothing. I took off on off the lines on the oil cooler rad and I don't think I have any flow through the radiator, but I'm not sure if the oil needs to be hot first to circulate? If I crack the banjo bolt on top of the hydro filter I get lots of air coming out with some oil. When I do that for a while it will then move for a minute and then the problem starts over. Got to be something I'm missing...dealer is no help really.

Here is an illustration of the flow for the HST.

The big yellow pipe draws oil up from the reservoir through the main suction filter (3). That pipe splits to go to the charge pump and also the main hydraulic pump. If your main pump is working, this much must be good.

The fluid goes into the charge pump and leaves by the dark pink colored line going up to the cooler. From the cooler, the blue line comes back and goes to the rabbit/turtle solenoid and to the input of the transmission (9).

When the fluid leaves the transmission, it returns through the smaller yellow line to the reservoir.

The cooler is always in the circuit. If pressure to the cooler becomes to much, there is a protective relief valve on top of the HST filter that will open, but this should not be a problem if you are having low pressure problems.

Bleeding the air out is probably a good choice. The repair manual does not have a bleed procedure, but it does say that air in the charge pump circuit can cause your problem. If you are sure your charge pump is not sucking, then eventually you will get all the air out by bleeding it. Just be careful to not let it get too hot or run dry due to oil starvation.

I'm still thinking air is getting sucked into your system somehow, but if all the oil drained out of the cooler when you changed the filter, that might be enough air to cause your problem. Maybe this diagram will help.

 

[housemasters]

Jinman,

I fixed it! I've been clearing some trees out back and apparently a piece of wood jammed in between that rubber 3-way connector underneath and the solid suction line. That was enough to cause air into the system. I had a hole in that rubber tee once before...I think NH needs to take a look into this weak area.

Thanks, Rick

 

[jinman]

Jinman,

I fixed it! I've been clearing some trees out back and apparently a piece of wood jammed in between that rubber 3-way connector underneath and the solid suction line. That was enough to cause air into the system. I had a hole in that rubber tee once before...I think NH needs to take a look into this weak area.

Thanks, Rick

Terrific! You are back in business. I think you have several people who agree with you about the rubber connector. I've never had a problem with mine, but I know it is there and needs to be checked from time to time.

 

[daTeacha]

Is there a similar piece on the 29? I've never noticed it, but never looked for it either. If so, could someone post a pic or some description of where it is?

 

[housemasters]

Yes there is...see attached.