8N Hydaulic Arms Lock Up Problem Solved

[Dennisinponca]

My 52 8N haudraulics locked up at the highest level possible with a 5ft. 3 pt. tiller hanging on a cherry picker waiting to be lowered into a pickup. I thanked the 8N grimlins for yet "another chance to improve my knowlede level on the 8N".

I went to the book (as I always do on a new problem). The choices were: Stuck Exhaust Control Valve, Plugged Oil Passage or Mechanical Linkage.

I opened the inspection covers, inspected the chamber for grimlins and stuck / broken linkage. I found nothing wrong with linkage. I used my hand to check to see if the exhaust valve was stuck. The lever moved easily as did the stem to the valve so I assumed a blocked oil passage.

I removed the top cover, pto shaft, and hydraulic pump.

Upon inspection and a messy air pressure test on the passages, I discovered the exhaust valve was stuck.

The valve has a spring inside it. When you move the actuation lever to move the control valve the stem on the exhaust valve pulls against the spring and this movement had fooled me into thinking the valve was moving.

In summary, the lever and stem were moving but the valve itself was not. Like the book said, "stuck exhaust control valve".

I cleaned the unit, including a light polishing on the valve and valve clylinder. I am now waiting for gaskets.

 

[souNdguy]

good job on the fix. and troubleshooting.

the sticky valve is one of those ones you just have to 'find'

soundguy

 

[cumbres]

I had to do this repair early this spring on our 8N. When I pulled it apart there was just a fleck of dirt in the valve causing it to stick.

What I found curious was the amount of sludge in the sump under the rear differential. I spent a lot of time and got very dirty removing the stuff by hand. I believe there is a small drain plug there but ours was frozen tight. I don't know how long it had been since stuff had been drained (we have owned the tractor now for 1 year) but it was probably an accumulation since the tractor was new.

Now a question. I find that some of the guys when they run the tractor get there feet into the dipstick and bend it a little causing it to not seal as well. Does anyone have a trck to prevent this from happening?

 

[lha]

I don't know how your feet could get that far back accidently .---lha

 

[cumbres]

(quoted from post at 06:20:42 11/24/10) I don't know how your feet could get that far back accidently .---lha

I don't think anyone would do it on purpose. But it does get bent up frequently.