Help 1948 Ford 8N Hydraulics possessed

   / Help 1948 Ford 8N Hydraulics possessed #1  

carpediem4570

Member
Joined
May 15, 2013
Messages
47
Location
Edmonton, ab
Tractor
MF65, Ford 8N, AC WF
Hello All:

Need your infinite wisdom regarding my Ford 1948 8n.

The hydraulics on my tractor are a bit tired. Depress the clutch or turn off the machine with an implement raised, and it will come to ground within 15-20 seconds.

I was discing a small field last year when the fluid for the three point hitch ran dry on the dip stick. I topped up the fluid but could not get the implement to raise up. At best, it would just lift the implement enough to bounce and skip it along the ground while driving.

If I took the implement off, the arms of the three point hitch would raise to the top.

Parked the tractor for a later look.

Finally pulled the old girl up and changed all the oils. Engaged the 3 point hitch with no load. up go the arms. Attach the discer and again, just barely of the ground. more like taking up the slack than getting it off the ground.

Grabbed my air compressor, removed the dip stick for the 3 point hitch and stuck the nozzle in the hole and gave it some air. While blowing air, I raised and lowered the hitch with the discer on. No change.

On my tractor, the top link rocker has three holes in it. I always attach the top link to the bottom hole. On a lark, I moved the top link to the upper hole. I engage the 3 point hitch and my pump comes to life growling low and up goes the discer. I try to lower the discer and nothing. Turn the machine off and down comes the discer. This happens three more times.

the fourth time, I raise the discer and it goes to the top and then drops to the ground. And goes to the top and comes to the ground. All while the lever is engaged in the up most position. It goes up and down like this four more times before I turn off the tractor.

Start the tractor again and now I have control of the implement. But not for long. Now we are back to the beginning again where I can just barely get it off the ground.

So, off I go to disc a small field and, up goes the implement. In the fie, it works intermittently, going to the top or just barely off the ground.

After discing the field, back to the house and I have spent the last two days researching the problem.

I will be taking the cover off to look at the hydraulics when it stops raining.

From what I've read, it could be anything from a worn relief valve to a scored cylinder and/or piston, loose control spring, stuck control valve, pump check valve, stuck inlet and/or outlet valves or worn quadrant draft control pin.

Can someone please tell me what foul demon has possessed my poor three point hitch or am I going to have to do an exorcism in the form of a complete tear down of the pump and hydraulics?

As always, your help is greatly appreciated.

Kind regards,

carpediem
Max
 
   / Help 1948 Ford 8N Hydraulics possessed
  • Thread Starter
#2  
Did a little checking out of the hydraulics today. Started with the simple one. Hooked up an implement to the 3 point hitch and raised it up. Surprisingly it went all the way up. However, after a couple of tries moving the implement up and down, when I left the lever in the up position, the implement would rise to the top and then fall to the ground, only to rise to the top again and repeat the process until I lowered the control lever. So I'm thinking stuck valve in the pump or possible scored cylinder or blown cylinder rings?

Prior to raising the implement to fully raised position, I moved the top link to the lowest hole on the top link rocker and, when the implement was up, I did the three finger check on the main control spring. Shouldn't turn if implement raised. Never mind three fingers, I could spin it freely with one finger; my baby finger.

So I'm thinking tighten the draft control yoke and new draft control spring plate with pin?

Tomorrow I take off the side plates to get a look at the boiler room, LOL.

Regards,

Max
 
   / Help 1948 Ford 8N Hydraulics possessed #3  
My Harry Ferguson does the exact same thing. I've never found an answer and I've had it a long time
 
   / Help 1948 Ford 8N Hydraulics possessed #4  
ntractorclub.com is a good site for info.
 
   / Help 1948 Ford 8N Hydraulics possessed
  • Thread Starter
#6  
Thank you for your help/

Hoo Boy, what a day:

Started ripping down the hydraulics to find the problem

Started by removing the top link rocker to expose the yoke.
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3356.jpg
Ugly but repairable. will take off the yoke and fill the divet in with weld.


Tried to unscrew the yoke from the draft control plunger. I thought it was turning to easy.
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3357.jpg
and you will notice the draft control spring plate is showing its age. Oh yeah, no draft control spring seat.


Since I broke the plunger, I might as well remove the hydraulic cover and check the piston and cylinder.
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3363.jpg
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3369.jpg
Not bad. Will replace the piston with the newer NAA model. Noticed there was no leather washer on the piston.
The cylinder looks good so I will reuse it

Not sure about the piston rod. Is it supposed to be flattened at the top like this? Should I replace it?
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3374.jpg

Next I remove the pump.

Regards,

Carpediem
 
   / Help 1948 Ford 8N Hydraulics possessed #7  
First.. quit trying to break your tractor by putting high draft loads in the top hole.

second, make sure you are in position control

third, use the correct oil.. that is a oil imersed belly pump.. it likes a goo utf or gear oil.. not a thin aw hydraulic fluid.

lastly.. you likely have a leaking lift pistol.. it's easy to pull the top cover, replace 4 gaskets, the piston.. swap with a naa piston and oring and backup washer.. hone the cyl with a brake hone, and while int here, replace the cam pin.
 
   / Help 1948 Ford 8N Hydraulics possessed
  • Thread Starter
#8  
Hey Sound guy:

Doing all that you said. If you look at my pics in the post above, you can see I removed the top cover and, pulled the pump yesterday. Might as well go all the way if I've come this far.

What is the cam pin?

Thanks for your comments and suggestions.

By the way, first time I've taken her apart since I got her three years ago. I have no idea what kind of oil the other guy used but I have the correct oil for it. Going to clean everything with solvent before I put it back to gether.

Like I said, might as well do it right.

Regards,

carpediem
 
   / Help 1948 Ford 8N Hydraulics possessed
  • Thread Starter
#9  
Another beautiful day so I thought I'd start work on the hydraulic pump.

Cleaned the pump with diesel fuel, a wire brush and some paper towel.
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3386.jpg
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3387.jpg

Pulled the relief valve, the exhaust control valve and the intake control valve.
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3385.jpg

I have a new relief valve on order. Do the intake and exhaust control valves need replacing and if so, where can I get new ones? I measured the intake and exhaust control valves and they both measure .592" and have a beautiful fit in the chambers. Chambers look good with no scoring.
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3390.jpg

Pulled the valve clamps to get a look at the inlet and outlet valves. Glad I've got new ones on order.


This was the yoke when I pulled it apart.
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3356.jpg

After a little welding and some paint and, she is ready to go back into service
http://i351.photobucket.com/albums/q465/carpediem4570/Ford 8N/IMG_3391.jpg

More to come when my parts arrive.

Regards,

carpediem
 
Last edited:
   / Help 1948 Ford 8N Hydraulics possessed #10  
none of your pics display for me.

the cam pin rides the cam on the lift rockshaft.
 
 
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