I need touch control advice

I am having a problem with my touch control on a 53 super C. I asked about this a few months back and I have not been able to resolve the problem. The hydraulics all work just fine. The problem is when you shut it off hours later it pukes fluid out of the top of the rear cyl. Both pistons on the touch control and now into the crank case. This tractor had all the system rebuilt about 10 years ago and has never leaked a drop till now and it will loose all the fluid over night. I don’t see how all the seals could go bad at one time. I have asked a local man who works on a lot of new stuff but is not very familiar with older equipment. He said it sounded like a clogged vent or something like that causing it to build up pressure and puke after the tractor sits. I have been studying my books and can find no such vent. The only parts I could find that remotely sounded like what I was looking for where a thermal relief valve and thermal relief valve screen. Has anyone experienced this problem and if so how did you resolve it. Am I barking up the wrong tree. Don"t consider any advice to simple. I"m not that smart.
Paul Shuler

That seems most unusual. I, like you, am under the impression that these systems are not vented. First off leaking into the engine crankcase. It appears as though your seal in you pump is either leaking (seems to be pretty common) or some pressure (which I would have to believe was on the input line) was forcing the seal out. I am assuming that when you say it pushes fluid out of the top of the rear cylinder you mean the fast hitch cylinder? I would think it would take incredible pressure to do that as that seal is under pressure when it's running and should me more than capable of holding back ~1000 psi. Do any of these leaks occur while running?

I am only guessing at this point but if it was me, I'd try filling up the system, run the tractor for a little bit, shut it down and then VERY CAREFULLY loosen and remove the fill plug on the unit and see what happens. That should eliminate building pressure or not. Beware they will usually build a small amount of pressure while running (as they heat up) and you will likely hear this release as you remove the filler plug. Best of luck, Sam

Hi Sam, I forgot to say that I can run it for an hour or more with not a leak one and everything operates just fine. Shut if off and come back in a few hours and there will be oil all over the floor and none or at least very little in the tractor.

Most peculiar. I'd still try filling it, running it, removing the fill plug (carefully, beware of the possible pressure behind it) and see what happens.

On the off chance, where are you parking the tractor? Just thinking about sun - heat - expansion and all that good stuff. It might explain the hitch cylinder but doesn't really work for anything else. Sam

It is supposed to be a closed, constant volume, system. The internal cylinders in the reservoir have fluid that follows the piston into the cylinder, thus displacing as much as used.
The rear cylinder is also 2 way, putting almost what is used to extend back into the res. Piston rod differential is all, which should be a partial vacuum when extended, and zero sum when lowered.
Many seals leak dramatically when under near zero pressure, but seal well when loaded in use. I think this is your issue.
Any oil leaking out of the piston rod is getting past the seal there. If it does, it could be the reason other factors are appearing.
If the rear cylinder control valve is not centering exactly, or is leaking, the hitch pressure could cause oil to be displaced back into the reservoir, with no oil going to the other side of that cylinder. This would pressurize the reservoir, and push pressure into the pump suction side (pushing on the seal on the pump shaft.)
If it were mine, I would put a 1/4 turn hydraulic rated valve in the bottom of the rear cylinder. When I shut it off, I would close this valve.
If all symptoms stop, I would look to those seals and Orings in the cylinder, and in the hitch control valve. Keep us informed! Jim

Thank you Jim, I will look into that. Hydraulics are a real mystery to me.

Without looking at one, or knowing for sure, I find it hard to believe there is no vent somewhere in the reservoir, if only for heat expansion and cylinder movement. In the parts book there is shown an "expansion plug"... wondering if that is actually a vent plug. Some systems I have worked on had a pipe plug with a porous brass breathable insert, and some that had the "wrench square" cross-drilled to breath a little. If one of these was replaced with a standard pipe plug, the reservoir would not vent properly.
Someone mentioned a seal leaking when not under pressure and sealing okay when in use... I have seen that too. If the fluid is getting into the crankcase, the only common seal is the pump shaft seal.

Question that MAY be related to you loss of oil: When you shut down are you "lowering" equip. to ground? With or without engine running? Move hyd. control levers AFTER shut down to relieve residual pressure?

Rick

I have a C and the touch control is vented at the fill port. A hole is drilled into the cap. Works great. Also sounds like you may have a bad seal somewhere. It shouldn't build pressure once the tractor is shut off.

Hi Rick, are you saying that moving the levers after the tractor is shut down will relive the pressure on the system. If so I didn't know that. It may be worth a try and see what effect that has.

I will have to look at my cap again. I was looking for one last night and could not find a hole but it was late and I am half blind. When you take the fill cap off I get a big whoose like when you open a can of soda that has been dropped. My cap may have been replaced or have a plugged hole. If it is a bad seal I can deal with that just didnt want to replace some seals just to push em all back out again. I HATE doing work twice.

There is no vent and you fill it with the arms back and you fill to about an inch below the plug. I've had two oily lessons with mine. First time I filled to the top with the arms ahead and the next time I moved the arms it blew the big welch plug on the front of the touch cont housing. Second lesson was in a big hurry to put a clutch in it one winter sat. morning, neeled down to pull the drain plug and forgot to loosen the fill plug, got hit in the chest with all that ice cold oil. Just put my coat and shirt in the wood stove.
If you have a loader with a supply tank hooked in maybe you need a vent but there wasn't one to start with.