Help With Leaking Hydraulic Fluid on L3710

Suburban Plowboy · May 26, 2019

Not sure if this belongs in the general Hydraulics area or what, but here I go.

My L3710 leaks hydraulic fluid like crazy. When I bought it used, the mechanic who inspected it said it needed new coupler. Yesterday, I cleaned off the manifold or whatever it's called, and then I let the tractor sit overnight. Photo attached. It looks like fluid is coming out of the detachable connection on the right, down low. There was no oil on the body of the quick coupler; the coupler appears to be doing its job.

I would guess an ounce of oil leaked out during the night. It's pretty bad.

I am guessing here, but it looks like the coupler connects to a short piece of pipe with threads on both ends, and the pipe goes into an elbow of some sort. If that is the case, the oil must be coming out of the threads on one end of the pipe.

This is a really tight space. I'm wondering how people remove these things. I have some crowfoot wrenches on the way from Ebay. Is that the proper tool? Also, should I omit Teflon tape/pipe dope?

I assume I should replace all three fittings (quick coupler, pipe, and elbow), since I don't know which one is the problem.

It looks like there are pipe wrench marks on the nut on the quick coupler, so I suppose someone with stellar qualifications already tried the MIT/NASA method of fixing it.

05 26 19 kubota leaking connection small.jpg

Suburban Plowboy · May 26, 2019

I realized I could not make the coupler any worse, so I took it off with Vise Grips. The threads had no sealant on them. I put some pipe dope on them and reinstalled the coupler. I worked the FEL for a bit and then put a bucket under the tractor with clean paper towels in it. If the towels are clean in the morning, it will tell me the threads needed sealant.

I can always put a nice, unmarred coupler in there later, once I know what's wrong.

If one coupler was installed dry, the others probably were, too. Wondering if I should apply pipe dope to them, if I ever get the right tool to remove them without chewing them up. Or maybe it's best not to fix it if it ain't broke.

Scook222 · May 26, 2019

There could be alittle residue left over to drip down in the bucket overnight so o would clean where you put the coupler back on really good, then wrap a paper towel around where you just put the fitting on. The others might not ever leak, so you could always leave them the way the are.

Suburban Plowboy · May 27, 2019

It looks like a drop of oil landed in the bucket. Hard to tell, because it spread out in the paper. Anyway, it was a tiny amount, and it may have been oil I failed to clean off the tractor when I left the garage. The pipe dope worked very well. Whether it worked perfectly, I can't say right away.

Suburban Plowboy · May 28, 2019

Interesting note: someone told me there are quick couplers that have real hexes cut into them, instead of two useless flats. The name of the company is Parker. Should be much easier (i.e. "possible") to work on.

Yesterday I managed to get a 7/8" wrench on the coupler, and I found it could still be tightened considerably. This gives me hope; if I didn't have it tight, maybe it will seal better now that I've tightened it more. I left a clean piece of scrap cardboard under it last night.