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3788 hydraulic problem


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Have looked at this very helpful  forum many times, got approved to post. Here's my tractor's issue: have  something you want to raise with the hydraulic remotes, and they barely work when you pull the lever, but then you notice the 3 pt is raising, and raising too far, finally it stops full up and then the hydraulic remotes work normally. But the 3pt has to stay in the too far up position. I am in the process of restoring this tractor, when I got it it had a chunk broke out of the rockshaft cover where the internal rockshaft arm came up and hit it. I put a different cover on and now think I see why the old one broke. One little clue from my attempts to trouble shoot this is when I blocked off the load sense line that goes from hydraulic valve stack back and down through rockshaft cover and into rockshaft cylinder the 3 pt was no longer affected by auxiliary hydraulics operation. Tractor has original pfc system, not converted to gear pump. Thanks for any help on what I ought take apart next.

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14 hours ago, oldiron user said:

Have looked at this very helpful  forum many times, got approved to post. Here's my tractor's issue: have  something you want to raise with the hydraulic remotes, and they barely work when you pull the lever, but then you notice the 3 pt is raising, and raising too far, finally it stops full up and then the hydraulic remotes work normally. But the 3pt has to stay in the too far up position. I am in the process of restoring this tractor, when I got it it had a chunk broke out of the rockshaft cover where the internal rockshaft arm came up and hit it. I put a different cover on and now think I see why the old one broke. One little clue from my attempts to trouble shoot this is when I blocked off the load sense line that goes from hydraulic valve stack back and down through rockshaft cover and into rockshaft cylinder the 3 pt was no longer affected by auxiliary hydraulics operation. Tractor has original pfc system, not converted to gear pump. Thanks for any help on what I ought take apart next.

Never ran into that issue on a PFC system I would check the unloader valve sounds like system pressure from the remotes is also sending pressure to the three point til it deadheads not sure what you meant by having damage to your cover unless some parts were missing Has there been any modifcations done to the hydraulic lines or hydraulic lines added ?

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No modifications. Damage to cover was from 3 point coming up too far and hitting cover internally. I'm thinking a checkvalve isn't holding allowing pressure to the load sense line to lift the 3 pt, but this is nearly over my head. Thanks for you interest.

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If the hitch raises faster with the hitch levers than it does with the auxillaries. Then I will say you are right. The draft control signal check is inoperative. It is located at priority valve end of signal line. Number 39 in the cnh parts drawing of the priority valve and lines.

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Thanks snoshoe, found the problem.  What I assumed was just a jic to sae adaper was actually a check valve, or used to be a check valve, all the innards are missing out of it as you can see by the bag tie sticking through it. It screws into the back of the auxiliary valve bracket,IMG_20210125_144245970.thumb.jpg.71deb21d2b1f5c7a9aa7685dd9a3c70c.jpg

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