Hydraulic Fitting

[Stephen1]

I have a leak on my bobcat bucket hydraulic cylinder. The one side of the fitting is weld on there is a square fitting onto the threads and oil is coming out. 
Before I try to undo the fittings I am wondering about the Allen key and slot in the end .
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[fluidpowerpro]

That just looks like an SAE port plug to me 

[Stephen1]

It's leaking on the other side. The square fitting can be undone and changed out?
I din't want to get into removing something with too much force. 

[fluidpowerpro]

I don't think the square end can be removed. The square head is typically 1 pc with the stem that runs down to the cylinder body. Your probably going to need to remove the cylinder and take it apart, and the have it welded to seal the leak.

[Stephen1]

that's what I was afraid of. JB Weld just might not be the answer.........

[fluidpowerpro]

Sorry, JB is great stuff but not for that.

[barbender]

We had a lot of welded ports crack on cylinders. They would get a hairline crack, to buy some time we would take a center punch and peen the crack. It worked pretty well for sealing the leak, actually. It would eventually open up more. Depending on where you were as far as getting service, we'll let's just say I've peened some of them 8-10 times before it finally got fixed😁

[Stephen1]

I can't see any crack , just getting a leak a big drop at a time. I think I will take the hoses off and see what I can see. I'll just make sure I leave the arms up enough I can get the cylinder off if needed. Save a few dollars if I just take the cylinder in versus the bobcat.

[Don P]

Prop and chock  ;).

[Big_eddy]

I'd clean and dry it very well and then see if I can figure out exactly where it is leaking using paper towel or a shop rag. In my experience, the first place to leak is the swivel fitting on the hose which is a simple enough fix with a replacement hose. Next suspect is the connection from the hose to the cylinder fitting. It that's an ORB, a new o-ring might do it. If JIC or NPT, then removing, cleaning and reinstalling is worth a try.

If the leak is actually from the welded on fitting itself, then someone with experience welding fittings to cylinders will need to repair or weld on a new fitting.

[Stephen1]

Prop and chock  ;).

And YES Don prop securely and chock!

[chevytaHOE5674]

Clean it off good and pinpoint the leak. I've welded many still on the machine with some good old 7018.

[Stephen1]

Well I blocked up the arm of the bobcat and took off the hose. I cleaned it all and could not see any cracks. I reinstalled the hose and tightened the fitting well. I have reduced the leak but still can not see where it is leaking. 
My next thought is I should wrap the fitting with teflon tape. I will get some from my shop this morning and try that when I get home. 

[PoginyHill]

Unless the connection is pipe thread, sealing the threads will make no difference. The seal is made by the seat of the JIC (looks like that's what the hose fitting might be) or O-ring for a face seal or SAE fitting. Could be that the fitting sealing surface is distorted (if JIC) and the only fix is likely a new hose.

[barbender]

Sometimes fittings will get stretched, either from damage or just fatigue, and there's nothing you can do but replace them.

[Big_eddy]

I agree with PoginyHill. Pages 27-30 at this link PA Hydraulics Book have some information about the different connection types. If ORB, then you can replace the O-Ring. If JIC, then other than confirming there are no burs, if snugging it up doesn't fix it, a new connector is needed. Only NPT benefits from Pipe dope. Teflon tape is not recommended for any hydraulics connections.

[fluidpowerpro]

If it's a 37 degree flared surface that's damaged and causing the leak, there is a product called Flaretite that may help.

[Stephen1]

Thanks guys. I am going to pick up a new pin for the forks from the hydraulic shop tomorrow, so I will take the hose with me. 

[PoginyHill]

I agree with PoginyHill. Pages 27-30 at this link PA Hydraulics Book have some information about the different connection types. If ORB, then you can replace the O-Ring. If JIC, then other than confirming there are no burs, if snugging it up doesn't fix it, a new connector is needed. Only NPT benefits from Pipe dope. Teflon tape is not recommended for any hydraulics connections.

That is a really nice reference book. Thanks for the link!

[scsmith42]

I agree with PoginyHill. Pages 27-30 at this link PA Hydraulics Book have some information about the different connection types. If ORB, then you can replace the O-Ring. If JIC, then other than confirming there are no burs, if snugging it up doesn't fix it, a new connector is needed. Only NPT benefits from Pipe dope. Teflon tape is not recommended for any hydraulics connections.

That is an awesome reference book!

[Stephen1]

It is a great reference book. I'll keep that download for sure. 
I now know , don't use teflon tape or pipe dope. 

[PoginyHill]

You will need pipe dope for any NPT connections. Just make sure it's compatible with hydraulic oil.

[Corley5]

I've never needed to use sealant on any NPT fittings. 

[PoginyHill]

Hmmm. Interesting. I may have to give "au naturel" a try.

[Corley5]

NPTF is used in hydraulic and fuel systems. The F stands for fuel. NPTF doesn't require sealant like NPT but they are compatible otherwise.  The same but different   ;)

[Stephen1]

I picked up my chrome bar for my forks from Greg at the Hydraulic shop. Great guy always gives me a break and spends time to talk to me. He has helped me with my old 93 LT40 and my bobcat a few times. He just put on a 20,000 sq ft addition and the boys are still working on equipment outside they are so busy. 
I chatted about the leak and the 1st thing he says, it's a bobcat right? Yes. Bring it in Steve, they are famous for breaking that fitting when you bump them to hard.