3 pt will drop when engine is turned off and load is on 3 pt. When I start engine the 3 pt will lift blade but pulsated up and down an inch or two. Shut off the engine and the lift drops slowly and I hear a clicking noise from the area of the relief valve. What could cause this problem?
CCWKen
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Doesn't sound like you have a problem. Is the pulsing on idle or when throttled up? If on idle, it's normal.
JC-jetro
Elite Member
Howdy,
Since the 3 point system is able to lift the load I can cautiously say that you do not have a pumping issue. I start with what you suggested in your post.
1.Your relief valve is bleeding by due to valve seat being worn out or contamination. That can only effect the pressure that your pump can develop and nothing else.
2. The spool valve in "open center" hyd system is the only way hyd oil/ pressure can be relived back to the reservoir. if the check valve in the spool can not hold the pressure causes the arms to drop.
I would first check the follwing before anything else.
-lift piston seal is leaking by. pretty simple to replace $10 and 1 hr tops labor if you do it yourself.
-shock load relief mechanism check valve in the lift piston head is leaking back to reservoir all the time with the pump catching up with the rate of the leak. very easy to check. if you need additional info I can post pertinent pics to help later.
JC,
JC, Thanks for the info. From what I read in your post the relief valve probably is not the problem, correct me if I have misinterpreted this. I will have to read up on how big a job it is to replace the lift piston seal and what to do if the shock load valve is leaking. Do these two items need to be fixed at the same time while the housing is disasembled? Ray
CCWken. Pulse is less when RPM are high. I have never had this problem before the lift started dropping after engine shuts off. I am concerned the pump will not be able to overcome the drop while I am grading the driveway with box blade on. I have had this tractor since bought new. Pressure is leaking down, I think JC is leading me in the right direction for repair. All suggestions are appreciated.
JC-jetro
Elite Member
ray,
Relif valve just regulate the pressure from discharge side of the pump before it enters the lift spool valve. It can relive pressure in to the reservoir (ie. rear differential) before entering the spool valve. it is not much of a fix on them other than inspection to find the cause. I have got several post that explains it in details. there are 3 things you need to inspect with piston seal to be the last.
1) Relief valve to clean and inspect.
2)shock load relief mechanism at the lift piston head.
hole in the middle is supply to the lift piston and the rate of drop needle valve. Second hole from the right is normal checked valve flow to the lift piston. flow can not go back from the second hole(check valved) hence making the middle hoe only way the flow can be returned to the reservoir and having an ability to regulate it by an external knob. The 3rd hole (3rd from right) is the shock relief that relives the oil from outside of the cylinder directly in to rear diffy when you carry a heavy load on 3 point and hit some obstruction.
The first stiff spring and the ball act as shock relif, clean and check for the roundness of the ball.
3) Lastly, check the lift piston seal and change if necessary. The way mine looked after 28 years. easy to replace.
Piston with a new seal install. There are two fat o-rings that seal the piston to the cylinder and the head. most likely you will not need to change them unless they look bad.
JC<
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JC-jetro
Elite Member
No, You will open it as the pics below suggest. Only open the outer bolt , stiff spring and first small ball for inspection. Take a flashlight and look at rust pitting on the valve seat.
JC,
The stiff spring and valve is between the fist and the second bolt. it will not hurt but you only need to loosen the most outer nut.
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I checked the relief valve and the shock valve both looked good except the relief valve had a bright ring around it where it seals in the seat like maybe it viabrates some of the time. Do you think the pressure tension might be to light and need adjusted? I have my box blade attached which weighs about 400 lbs.
JC-jetro
Elite Member
The only way you can do that to put 3000 psi liq filled pressure gauge on the cylinder head, raise 3 point with no load and continue to raise where the relief starts to chatter and relive, that would be your pressure setting. I think it should be around 2300 psi. notice that you do not have shims behind the spring to adjust but can change the spring tension by adjustment nut provided. All of that said it can nor explain 3 point dropping. my two other options would be to check the piston seal and lastly your 3 point spool valve. I'd exhaust all before I tackle the spool valve.
good luck,
JC,
JC I noticed in one of your earlier posts that you had pictures of the lift cylinder and piston when you replaced the seal. My question is when you take the 6 bolts off the piston housing does the cylinder and piston assembly come out with the housing? I have a shop manual but it does not go into detail about this. Also what is necessary to do to seperate the piston and how big a job is it to replace the assembly into the tractor after the seal is replaced. I figure since you have done this procedure you probably can pass along the do's and don'ts to get the job completed correctly. Ray
JC-jetro
Elite Member
Hey Ray,
The whole assembly comes out as whole. cylinder and head comes apart by a little force, they are oringed together if there is a term like that. Make sure the orientation of seal lip. it is a one time try ,can not take the seal off without damaging it. Also be careful with piston orientation and the ram rod that rotate the rock shaft.
JC,
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JC or Anyone else, I found the piston seal cracked and am now replacing it. Is there any special way to put the seal into the piston? Does it have to be warmen up, oiled or do I just stretch it over the piston? There must be a trick to it. I am a first time replacer. I need all the help I can get although if it streatches it looks easy enough. I don't want to ruin it and have to reorder. Ray
Texas Blues
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Hey Ray, I just replaced mine a few days ago. It is a tight fitting seal. It was tough to get it to go over the piston because the seal didnt stretch much if any. I shot some wd40 on mine and I suppose it helped some. I did it by hand without the use of a pry tool and eventually got it to go over the piston. The slicker it gets I imagine the tougher its going to be getting a grip on it to stretch it over but it will go. I wouldnt suggest using any pry tools on it as you may cut it or damage the seal in another way. Also as JC has shown, make sure you have the lip of the seal in the right direction. I think his pictures show the flared side of the seal should face the red end of the piston (the top). Look in those other posts about hydraulics and you will see some really nice pics from JC. Good luck! Tex
Texas Blues
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Texas Blues
Gold Member
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Glad to hear it Ray. I was fortunate as well, the piston seal was all mine needed.
ComputerGuy
New member
Thanks to all you for your posts. I have "taken over maintenance" of a 1986 Ford 1910 that sleeps under a hackberry tree when it is not being used. I just bought a new Modern 5' mower to replace a worn out Howse, and the lift was not doing a good job lifting it. After reading this, I decided the seal in the lift cylinder might be the culprit.First, I drained all of the hydraulic fluid I could get. The old fluid looked like chocolate milk! While it was empty, I took the head off -- not a problem because the weight of the lift arms wanted to push the rod all the way through -- much easier after I supported them!
Imagine my surprise to find that the seal was completely gone! No telling where it is.
The new seal kit they sold me is different from the pictures -- they said this was a new design. It has a black "rubber" O-ring and a white "nylon" ring that is split. They said the O-ring went to the "oil side" of the piston, and the white ring was used to fill the gaps.
Took some "encouragment" to get the piston back in the cylinder, but it finally went in. Reassembled everything, filled the transmission with new hydraulic fluid, replaced the filter, and tried it out. Now the 3 point hitch is rock solid again, and the "position control" lever can now be used to, well, control position!
I briefly thought about buying a new tractor with about the same horsepower, but I think this one still has a lot of life left in it after I finish my rehab. As time (and funding) permits, we plan to build a garage and it will get to sleep inside -- should make a lot of difference.
Once again, thanks for the pictures, the advice, and for posting notes about the journey. Not only did I save a lot of money fixing this myself, but I learned a lot more about how the hydraulics work on this machine!
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JC-jetro
Elite Member
Great to hear your success Computer Guy, There is a lot of good info and knowledge here about 1000 series ford tractors. They are well designed and not at all difficult to work on and pretty manageable for most of us "Weekend Warriors".
JC,
, There is a lot of good info and knowledge here about 1000 series ford tractors. They are well designed and not at all difficult to work on and pretty manageable for most of us "Weekend Warriors".JC,
ComputerGuy, One other thing to keep an eye on is the rubber boots on the gear shifters. An earlier problem I had when my tractor sat outside all the time was water getting into the transmission through cracked boots when it rained. Water in the transmission can cause the fluid to get a milky color (or chocolate milk color?) When this happens the lift will be jerky as the water interferes with the hydraulic performance. Check your two boots to see if they are cracked or raised up on the shifters. Replacement is quick and easy by sliding new ones down on the shifters and they are inexpensive as well. Cracked ones should be replaced. Ray
