# 1966 656 IH Farmall Steering Problems



## cbrunner (Nov 1, 2012)

Hello.
I am working with a 656 Diesel steering issue. When I got to the tractor my friend told me that he had been bailing the field, the tractor was getting hot, and he lost steering. Upon inspection I found that the hydraulic pump to the steering system was moving fluid (by disconnecting output tube). I did not take a pressure or flow measurement. I checked the pilot valve and found the spool clear and moves easily. He had already disconnected the steering wheel/motor and we found no oil moving from the pilot valve through the ports where the steering wheel should have been connected.

I stripped the flow divider under the pilot valve and found the main spool stuck, pushed all the way into the housing. After some persuasion I was able to jar the spool loose, remove it from the housing and inspect. I found aluminum shavings in the housing were jamming the spool. I also removed the relief valve from the same flow divider and inspected it. The valve showed no signs of damage, but was also contaminated with aluminum shavings. I fit the flow divider with new seals, and after ensuring the divider spool freely shifted we reinstalled it on the tractor.

Before re-firing the system, we checked and found the previous owner had liberated the filter from it's housing. We found and installed a new filter and bypass screen. I found it odd that the dipstick on the tractor oil reservoir (at operators left foot) read over-full and we had no fluid in the filter housing. I even checked the passage from the "tank" to the housing with some wire to be sure it wasn't blocked (free and clear).

After reassembly and air purge we began testing. Initially we were not getting much for flow, but a few adjustments to the stop on the flow divider seemed to resolve that issue (I need to go back with my flowmeter and set it properly). We were able to purge all of the air from the steering wheel (hand pump) area by leaving a line off. After reconnecting the lines, we gauged the output from the pilot valve to the steering box and found we would only get intermittant pressure of between 50psi to 250psi while cranking the wheel. Once we stopped moving the wheel, the pressure quickly returned to zero. During these tests, the relief valve in the flow divider was allowing fluid through.

I didn't have any daylight left to gauge the main pump output pressure or flow, but this AM while it was still quite cold out my friend told me he was able to get the pressure gauge to read almost 800 before it dropped off.

I am getting ready to make another trek out into the field for more troubleshooting - any suggestions on what to look at? I planned on first measuring the pump pressure and flow and working speed. If those tests worked out I would then move to the pilot valve and see what the output pressure and flow to the steering wheel was.

I suspect the main pump is giving up - but I'm hoping that I'm missing something. Is there a residual pressure valve to maintain a minimum pressure in the steering system? Anyone have the manual pages for this part of the system?

Thanks
Chris


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