Farmall 400 Hydraulic System

Tim Nichols

New User
I have a 1956 Farmall 400. The hydraulic system stopped working. I think there is part of the brass screen filter blocking the passages, don't kwow where at. What would be the best way to check if it in a line somewhere or in some of the valves? Is there a way to flush or back flush the system?


Thanks for your help

Tim
 
What is it doing?

Unless the engine is laboring, the pump is making funny noises, and things get HOT in short order, it's not plugged.

That said, if fluid won't go through the system at high pressure, you can't hope to accomplish anything useful by "flushing" at a low pressure.

If something is lodged in there you will need to pull the system apart and remove it manually, IMHO.
 
(quoted from post at 12:56:18 08/28/14) What is it doing?

Unless the engine is laboring, the pump is making funny noises, and things get HOT in short order, it's not plugged.

That said, if fluid won't go through the system at high pressure, you can't hope to accomplish anything useful by "flushing" at a low pressure.

If something is lodged in there you will need to pull the system apart and remove it manually, IMHO.


I wanted to change the fluid and filter due to low pressure when my steering, loader and fast hitch started moving really slow. I checked the fluid and it was at the proper level.

I drained the fluid and pulled the filter noticing the brass mesh on the filter was about half gone. Checked in the resovoir and did not find any of the mesh.

Installed the new filter and filled with fluid and have no pressure at all. System not making any noises.

Looking for ideas of where the mesh may be blocking the system at, if I need to tear the system apart or is a flush possible to clear the blockage.

Tim
 
Was the mesh there the last time you cleaned screen? Usually what happens is it gets scraped off when pulling out a plugged collapsed screen. Other wise, as this is on the suction side of pump it might be lodged in the passage in reservoir or line to pump. Most likely though you just lost prime now. Run nose of tractor down a steep incline(ditch) or pressurize reservoir. Note, breather on top of reservoir needs to be plugged to pressurize or it will just pop off most likely. Other methods but these are what I use.
 
(quoted from post at 21:40:31 08/28/14) Was the mesh there the last time you cleaned screen? Usually what happens is it gets scraped off when pulling out a plugged collapsed screen. Other wise, as this is on the suction side of pump it might be lodged in the passage in reservoir or line to pump. Most likely though you just lost prime now. Run nose of tractor down a steep incline(ditch) or pressurize reservoir. Note, breather on top of reservoir needs to be plugged to pressurize or it will just pop off most likely. Other methods but these are what I use.

The filter with screen was intact at the last fluid and filter change. I will give your suggestion a try.

Thanks,
Tim
 
Since you say there is no pressure at all, I would first take the oil lines off going to the pump & check for any obstructions on both the pressure & return sides. Once back on I would remove the small plug on the top of the pump and fill with Hydraulic oil.
Then replace the plug & start & let idle to see if the pump is free of air, or if things start working.
 
Your reply at the bottom of the page, suggests to me that you have lost the prime to the pump. You are air locked. Remove the plug on the top of the pump, fill with fluid and put the plug back in carefully. It is easy to cross thread. Start the tractor and if you still do not have pressure. repeat the process. If you had low pressure to start with, you may need to replace the pump.
SDE
 

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