mf204 3pt hitch Hydraulics

Dave_1248

New User
hi

I hope someone can give me a good direction here. We bought this thing recently,and after I changed the water logged oil, the 3pt hitch worked. But now its not working again. I checked the oil for water(there is a little bit, but not crazy). Bought a manual, drained 5 gallons, opened the inspection port, and moved the control valve lever by hand. The lift tries to go up, but my box blade is too heavy for it. I'm thinking I don't have enough pressure. I do not see the pressure relief valve operating, nor does my pump sound like its broken. The 3 pt hitch did stick in the up position a few weeks back, and took about 2 hrs to drop after I turned engine off. That makes me think I have a good cylinder.

Any help?

Thanks
Dave
 
ok so dived into this thing again today. Used my cell phone to get some video inside the case while it was running. The one pump cylinder seems to be leaking. It looks like the rings may be gone, and it squirts oil up every time it is pushed into the housing. I also got a good look at the lift cylinder, and it is leaking. But the big thing is, the linkage for the position control lever seems to be out of adjustment. I was able to push it with my fingers and get the lift to come up. So I guess at the very least I need to adjust the linkage. Does anyone have a procedure for adjusting it in the tractor? Or do i have to pull the cover?

Dave
 
Also,

Does anyone have pictures of the lift controls once the cover is removed? The manual only has bad black and white ones.

Dave
 
Hello Dave,
It will be quite likely that you have a broken ring on the scotch yoke piston assembly. I believe that early ones did not have rings so can't be sure. It is also possible that the poppet valve inside the chamber may be seized. If that has happened that is why you are seeing oil blown back into the transmission. If you have oil leaking from the lift cylinder then that may be due to a pitted cylinder or indeed broken or badly worn rings.
You will see the lever that is attached to the pump being acted upon by the vertical levers coming down from above. If you were able to move the pump or vertical levers manually this is normal. The spring in the pump valve requires approximately 3lb of pressure to activate it. All that you are doing is overcoming this force.
Some adjustments can be done with the cover in situ but I think that you have further problems which will require the removal of the cover.
The two photos that I have posted show part of the linkage. Note the flat that is worn on one roller and its corresponding wear mark on the cross-shaft cam arm. A new roller was turned up and the arm replaced. Your manual will tell you how to check and overhaul the control spring in the rear end of the cover (where you attach the top link). This should be carried out before removing the cover. It will affect the operation of the linkage if badly worn or adjusted wrongly.
DavidP, South Wales
a172584.jpg

a172585.jpg
 
I think it is likely that I do have a broken ring on the pump. I'm going to let this pass for now. My main concern is the linkages for the position control. I can get the lift to work, if I push the control linkages with my fingers. I really need a different manual though. The hydraulics I have are similar to the TO35 tractor, but my manual shows the ones similar to the 135 tractor. So no help from the manual there. Anyone have something they can send me on a TO35? I'm really still trying to understand how the system works so I can properly troubleshoot it.

Dave
 
The system is actually very simple, but the adjustments are critical to get correct.
John(UK) has a great set of instructions that he has put together. He's a tractor engineer from back when these tractors were fairly new. I can't share the info with you as it belongs to him. I'm sure he'd be happy to email it to you though. [email protected] is his email. Put "Ferguson tractor" in the subject line or he may not read or see it.
He sometimes posts on the Harry Ferguson forum but I haven't seen him there lately.

I have a 202 tractor and the hydraulics are the same as a TO35 (I have one of those too). In fact the 35 has parts in it from the 202 right now. The 204 being an instant reverse machine may look a little different under the cover but I'm not sure, I've never had one.
 
The system looks simple, just cant seem to wrap my head around how the cams work on the control levers to translate it into control valve motion. I'll give John an email and hope that gives me a push in the right direction.

Dave
 
The bottom line is, you are simply controlling a single valve with multiple input and depending on that input the valve will either raise the lift, or lower the lift. I always strive to understand HOW it works rather than to simply go through the motions and guess at it. It really helps with troubleshooting.
 
I just opened a youtube channel and posted some video i took from my phone. Its raw uncut video. I apologize for the shaky and sometimes sideways video(looks like youtube fixed it). I think it shows the controls pretty good, if you were to actually know what you are looking at. In the "valve link" video the levers that actually move the control valve act funny, but I really cant see why. If anyone wants to look.

Thanks
Dave



https://www.youtube.com/channel/UCVqTXEg3cAClE7hN8fkT7PQ
 
ok so I really need to do something with this, but my manual only shows how to set up the more modern hydraulics. Can someone tell me the difference between the two?

Dave
 

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