Nagging hydraulic leak

[Carykong]

Jinman, Could you have spliced in some flexible rubber hydraulic line to mitigate the bend? Just wondering.

 

[jinman]

Jinman, Could you have spliced in some flexible rubber hydraulic line to mitigate the bend? Just wondering.

Ha! I thought of that, but by the time I got two splices done, it would cost as much as a new pipe. I'm sure doing the job right has a lot more to do with success than anything. If I had the new pipe, I now have all the proper tools and technique to do the job right, without any "folding, spindling, or mutilating" of the pipe.:laughing:

 

[jinman]

After hauling 5 loads with my dump trailer, the stinkin' seal blew out again.:mur: This time, I'm ordering the whole pipe and will try that. I'm also going to talk to my dealer's service manager to see if he has any tricks. This SHOULD NOT be happening. I'm not working the hydraulics or trailer hard. The dump trailer is hooked to my remotes, but it is only loaded with 4-1/2 yd of material in a 7 yard bed. It's not hooked to my 3PH, but to the drawbar, so the only time the hydraulics work are when dumping the trailer.:confused2:

 

[wdchyd]

Jim,

Just for yuks when you take it apart again.....could you measure the "Groove" thickness and outside dia....

(assuming you have a set of calipers of sorts)

Bill

 

[Hooked_on_HP]

After hauling 5 loads with my dump trailer, the stinkin' seal blew out again.:mur: This time, I'm ordering the whole pipe and will try that. I'm also going to talk to my dealer's service manager to see if he has any tricks. This SHOULD NOT be happening. I'm not working the hydraulics or trailer hard. The dump trailer is hooked to my remotes, but it is only loaded with 4-1/2 yd of material in a 7 yard bed. It's not hooked to my 3PH, but to the drawbar, so the only time the hydraulics work are when dumping the trailer.:confused2:

Jim are you always using the dump trailer when it blows the o ring.
Bill

 

[jinman]

Jim are you always using the dump trailer when it blows the o ring.
Bill

No, not at all. Most times I've been using the loader. When I get the new pipe in, I'll measure the pressure, but I have no reason to believe it is anything but correct. We'll see. . .

I'll try to measure the gland (groove) dimensions (depth & diameter). I think I have my micrometer stashed away somewhere.

 

[jinman]

Ordered the hydraulic tubing this morning. It should be at the dealership on Wednesday.:thumbsup:

 

[jinman]

Tubing arrived Wednesday as promised and I picked it up yesterday. This morning, I decided to tackle the job of replacement. The first thing I did was crawl under the tractor and inspect the old tube. As I expected, I had parts of two o-rings hanging out the back side of the diverter/regulator end flange (1st photo). The Viton is red and the HNBR is green.

When I removed the tubing, the Viton ring had exploded due to over-compression. The HNBR had an extruded "tongue" on one side (2nd photo). I compared dimensions of the old part to the new one with my antique micrometer and found them to be as close as I could measure. The o-ring that fits is supposed to be .969" o.d., and .0945" o-ring thickness. I measured the gland at .9515" wide and .0915 deep. That means the o-ring diameter is slightly compressed to fit into the gland and it is only .003" thicker than the gland depth. My gland diameter measurement may have been off a bit because one of my tips is nicked on my old micrometer, and it's hard to measure diameters on such a shallow gland.

The real story was when I put the micrometer's edge across the flange (final photo). The ends of the flange were slightly bent so that the center around the gland had a gap when the flange was tightened. You can't see light in my photo, but I could easily see it under the mic on the old tube flange and not on the new one. The new flange is perfectly flat.

I installed the new tube carefully, tightening the diveter flange end before tightening the four bolts into the hydraulic pump. I cranked up the tractor and raised the bed on the dump trailer until the cylinders extended to the end and the pressure relief popped. I did the same with the loader. NO LEAKS!. I'm not sure it's fixed, but I've done my best to do the job right. I put the correct o-ring in from New Holland instead of my experimental ones. Everything is back to stock and I've got my fingers crossed that this time it will all be good.

I didn't read the system pressure, but I'll try to remember to do that tomorrow.

 

[wdchyd]

Jim,

The only thing I can think of is the material that the flange is made of is too thin or not strong enough tensile strength to withstand the pressure spikes.....

the oring failure does look like extrusion through a gap, so if the flange flexes under pressure it may open up on the side allowing the oring to blow...

I don't have my oring info at home but can check at work next week but it seems as though the cross-section of the oring should be thicker than .003......I'm thinking it should be about 10 to 20% thicker than the depth of the oring groove....

On the old extra tubing you could weld up some kind of reinforcement on the side of the flange to stiffen up, then surface grind or mill the face flat if the welding distorts the flange.....

It just looks as though the flange with only 2 bolt holes on the long sides are not heavy duty enough.....allowing to flex under pressure

Just my :2cents:

 

[jinman]

Bill, your guess is as good as mine for sure. I think your idea of a 90 durometer o-ring is a good one. I had two of the stock o-rings and just decided to go back completely stock. After all, it worked for 1700+ hours that way and didn't start leaking until I took off the pump. Not only did I bend the tubing some when I first took it off, but I just remembered that I tightened the flange down the first time with the o-ring out of place. I always coat o-rings with a tiny bit of grease for sticky, but somehow got the o-ring out of the gland. That means I could have bent the flange when putting in the o-ring. I can't tell you how stupid I felt for botching this job so badly. It was a bad day. The same day I cut the o-ring inside a quick connector when I installed the loader hoses.:confused2: I completely lay this problem at my feet. This one's on me.:ashamed:

Also, I wouldn't swear by my numbers and measurements. The numbers I came up with for the gland are based on the oem o-ring dimensions and my measurements. As you said, .003" is not much crush on an o-ring. Not being a hydraulic expert, I don't know what the normal compression dimension is. I could easily have been off a couple of thousands with my measurement. I really need to get a dial indicator micrometer instead of this old antique with a vernier scale.

Thank you very much for your advice. When I was at the dealership to pick up my tubing, I first stopped and talked to the service manager. I asked him if he had ever had one of these leak. He told me they had and that they always just replaced the tubing to fix the leak. I think this part has to be handled carefully instead of being monkey-fisted like I did the first time around. Just keep your fingers crossed for me that this time the oil stays instead of sprays.