[4thtexas]

I have a 2955 MFWD that I began blowing steering cylinder seals. This steering cylinder is double acting integrated into the frame. The first time they were the original seals and I thought just old. But every time I replace them both inner and outer and the last time I took it totally down replacing all seals ( didn't see anything wrong with the center seals). Put it back together and within 5 hours of operation there appeared a leak at one or both sides and the outer seal was protruding outward in one spot like it had had high pressure force on it or the seal (which is a different material from original) had swollen too large for the cylinder and just was pushed out at one point. This has happened on both sides. I don't know if the brakes are tied into this hydraulic circuit but I was using them to turn the tractor in tight places while bushogging as always. That's what this tractor mostly is used for. If it is a pressure problem, can someone elaborate how to troubleshoot. I am not experiencing any hydraulic issues with the steering, brakes, or implement that I am aware of. I just thought of one more thing if it is a return pressure issue, could there be a restriction on the return side that does not allow the oil to move out of the cylinder opposite the turn thus causing the seal to be pushed out? Where would I start to troubleshoot that if the initial pressure is correct?

 

[Tx Jim]

Welcome to GTT
I'd recommend acquiring a 5000 psi gauge and checking stand-by pressure. Pressure should be 2250 psi. You can check at rear breakaway couplers(wet lines)

 

[Treefarmer]

Pressure and correct fluid

I agree with checking the pressure to see if a relief valve needs adjusting. Another question- are you using an aftermarket hydraulic fluid? A friend with a Massey used a non Massey fluid and it was not compatible with the seals. He ended up replacing multiple seals, some of which were inside the tractor. :banghead:

Treefarmer

 

[Tx Jim]

I agree with checking the pressure to see if a relief valve needs adjusting.
Treefarmer

Technically on ag tractors closed center hyd systems doesn't utilize relief valves similar to open center hyd's but relies on a stroke control valve to regulate pressure

 

[4thtexas]

I agree with checking the pressure to see if a relief valve needs adjusting. Another question- are you using an aftermarket hydraulic fluid? A friend with a Massey used a non Massey fluid and it was not compatible with the seals. He ended up replacing multiple seals, some of which were inside the tractor. :banghead:

Treefarmer

Thanks TF, I can get a gauge and I will check next. No aftermarket since I have owned it a number of years and at least 6 changes. After I check the pressures I'll find the adjustment if necessary.

 

[4thtexas]

Technically on ag tractors closed center hyd systems doesn't utilize relief valves similar to open center hyd's but relies on a stroke control valve to regulate pressure

I may have to visit my JD dealer to pick his brain a little then as that advice was over my head. Since it is harvest time maybe he wont mind sharing some info that will keep my tractor off his long list of immediate needs he has now. Thanks again!

 

[4thtexas]

Welcome to GTT
I'd recommend acquiring a 5000 psi gauge and checking stand-by pressure. Pressure should be 2250 psi. You can check at rear breakaway couplers(wet lines)

Well, I installed a pressure gauge at the fitting where steering hose connects to cylinder on left side by replacing it with a tee for the gauge. Started and checked at both idle and high idle while operating the steering back and forth fully. I was reading 1000 psi to a max of 1500 psi when pressure was applied and it dropped to close zero when turning the opposite way indicating to me that there is no over pressurization and no restriction in the return. It was suggested to me that the vent for the hydraulic system may be plugged and as it heats up during operation that the pressures could rise. What do you think? The only vent I can find is that the cap at the rear case for filling is vented internally so it was also suggested that maybe I run it with a rag over the filler neck without the cap to see if it corrects my problem and then address the vented cap. What do you think?

 

[Tx Jim]

Clogged vent on hyd system WILL NOT cause pressure to rise. The high pressure Hyd pressure is determined(controlled) by stroke control valve in frt hyd pump which factory setting is 2250 psi.

 

[MFreund1]

My GUESS is the chrome rod is worn and smaller in diameter that it originally was.

 

[Tx Jim]

My GUESS is the chrome rod is worn and smaller in diameter that it originally was.

In all my yrs around tractors/equipment I've never seen a cyl rod worn enough in diameter to cause seal to leak. I think if rod was worn enough to cause this type leak it would no longer be chromed.

 

[56FordGuy]

In all my yrs around tractors/equipment I've never seen a cyl rod worn enough in diameter to cause seal to leak. I think if rod was worn enough to cause this type leak it would no longer be chromed.

I've seen it a few times, but only a few and never on a steer cylinder.

That said, if the pressure going to the cylinder is right then the next suspect component would be the cylinder itself. Ordinarily the seal is secured by a snap ring or circlip, then the wiper goes in. I can't look at the JDP breakdown right now, but if this one is built the same way I would double check that all the parts are in the correct order.

Another thought, if the center packing was bypassing it might be possible for the cylinder to be putting pressure on both sides at the same time, maybe not evenly but enough that the fluid might be fighting against itself when turning creating higher pressures inside the cylinder than you can measure at the supply lines. In any case, I think the next step if the supply pressure is good and mechanical component of the steering (tie rods, spindles, etc) is all free would be to dig into the cylinder again.

 

[Zebrafive]

Here's the cylinder 13 is the piston for reference
9 is the seal, 10 is ring, 11 is washer