350 hydraulics

Working on my IH 350 High Utility. The hydraulic valve for my rear port won't hold the pressure in the cylinder for my mower. When the fluid is cool it does better. When it's warmed up, though you have to keep feeding it to keep the thing in a lifted position.

This valve control back in by the side of the seat.

Question is: Can the valve be repaired with a kit or by other means? What is in the valve to control the pressure?

Appreciate the help,

Bob

O rings are in there. One is bad. If the spool is scratched deeply the New O ring will fail or not fix it. The valves are common to many IH tractors.
The handles are not too common. Clean cloth topped bench, take pictures, keep it all clean. Do not dig out O rings with a knife, use a dental pic tool.
JimN

OK, thanks a lot.

I'll see what I can do.

Appreciate it.

The o-rings only keep it from leaking to the outside and do not hold the load up. Fit of spool to body does that. Your spool is worn, add a single acting check valve to solve your problem. If you are using a double acting cyl it may be leaking internally causing pressure to equalize on both sides of cyl and in effect the displacement of the piston rod is holding the load and pressures get much higher and even a good valve may not hold the load up.

Bob,

Actually, the control valves on your 350 were not designed for positive shut-off, and no amount of fooling around with their O-rings, etc. is going to change that.

IH had a "cross-check" valve which was included as standard equipment with the fast-hitch option on these tractors to keep the hitch from bleeding down. This is a rectangular block which bolts directly onto the control valve block -- you may have one already on your tractor assuming it has the fast hitch. When working properly, these are extremely effective and will hold just about any load, regardless of how heavy, indefinitely. But they only work in one direction. You could add one of these to your remote port to keep your mower cylinder from bleeding down. You might be able to get one from JP Tractor or some other salvage yard. If you have a Parts Manual (TC-57A) for the 300/350 Utility tractors, the check valve is detailed on page 315, and shown as part of the fast-hitch system on page 294.

Another option, which is what I use for my remote since it works in both directions (for a double-acting cylinder), is to install a hand valve in one of the hydraulic lines. Use the control valve to get your mower cylinder where you want it, then close the hand valve. Obviously you have to use a valve rated for the hydraulic pressure. A quarter-turn ball valve works well for this.

Hope this is helpful. Good luck.

I won't disagree with the Oring issue, but the valves can and do hold in both directions The lowering safety check is on the hitch control (if equipped with Fast Hitch) but the remote valves used on the tractor, and the FH control do not leak (we held up a V snowplow that was articulated from the rear FH drawbar in the down position for miles down the road With no loss of height. Many have been used with loaders (no loss of set height. JimN

Thanks a lot for all the help and the ideas for options.

This tractor has the fast hitch. The mower I am using is a sickle bar mower, so the problem I have is keeping the bar up on turns etc.

I'll see what's available for a fix on this thing.

Again - many thanks

If the mower cylinder is 2 way, and the non lift end is plumbed into the system, it could be that the cylinder is bypassing internally, just a thought. Jim

I second everything Pete 23 said. I would take off the mower and lower the hitch all the way to the ground, and check which hose seems like it is pressurized when you hold the control lever in the "lower" position. Shut off the engine and stick a jack under one side of the fast hitch to raise it just enough to take the pressure off the cylinder. Then disconnect the hose that DID NOT pressurize from the fitting on the cylinder and point it into a bucket or wire it to the tractor so it is pointing down where any oil coming out of it won't hurt anything. Connect a short hose, if you have one, to the cylinder fitting and point it where any oil coming out of it won't hurt anything. Start the engine and set the throttle at idle. Slowly push the control lever into the "lower" position. If any oil continues to flow out of the cylinder with the lever held down, the O-ring on the cylinder piston is blown, and you will have to disassemble the cylinder to replace it. I would bet that is what is happening on your tractor.

Yes, a new perfectly manufactured spool type valve as used in the 350 will hold a load in both directions (up to a point) and that point is when the pressure required to hold the load and viscosity of the fluid reaches the point where fluid will leak through the clearance required to allow the valve spool to move freely in it's bore. A worn spool or bore will leak that much sooner. Like Dick said, that is why IH used a check valve on the hitch and made them available for the other valves as well. Some were single action, some double, and some were alternating check valves. One of the major complaints against IH by John Deere oriented customers over the years was always that IH tractors always allowed hyd cyl's to settle. Deere SCV's, had a positive seal and that is why you saw high pressure safety relief valves on deere cylinders as they would blow cylinders and hoses when parked out in a hot sun and the IH would not as they would seep enough to relieve the pressure. I found out the last few years I worked at a Deere dealership that this positive seal feature was very expensive to maintain as I repaired a quite a few SCV's and it was a money making deal for dealer. Could have bought a new aux valve on the IH for what was put into them as a regular repair. The thing I always like about a spool type valve is the control you have when inching a cylinder into a load and you don't have that precise control with a poppet type valve.