J.D. 70A BACKHOE CYLINDER REPAIR

[bennett2497]

Hi'

I have a J.D. 70a bachoe on my 855. The swing cylinder starting leaking. So i rebuilt it with a friend that has done several other brands. The last thing we realized was that the end piece just slid in with a c-clip on the end , did not screw in. We figured under pressure that it would leak. So we used hydralic sealer to seal the end. I waited 24hrs ran it and it leaks worse. Could somone please tell me what to do or what to use. Thanks alot , hard to do without it on the farm ! Thanks , Curt

 

[Wayne County Hose]

Hello Curt and welcome to TBN.
Your terms are a little vague to me so please excuse me. I'm pretty sure I know the gland style you describe. There is a wire that either goes in the end of the cylinder bore to hold the gland in or it goes in the side of the cylinder and you turn the gland to remove the wire. In either case, there should be an O-ring on the gland just inside the wire retainer. Did you replace it? Was it there when you removed the gland? I'm guessing that the leak is from between the gland and the cylinder housing, not from the rod area. If it is from the gland/cylinder O-ring, hydraulic sealer would hurt more than help.
What kind of farm and where?
Also, with cylinders, pictures help. The more the better. I dun cant reed 2 wel so i liike pichures man!
Andy

 

[bennett2497]

Hi Andy,

There is no wire ! This machine is probably 15 years old. But it must be a different style. That end piece just slides in the end of the tube and a c-clip holds it in. Pictures are not going to help much because its together and on the tractor. Thanks , Curt

 

[Wayne County Hose]

Hello Curt,

I know what style you have. Hopefully Kenny will show up with a parts breakdown. You need to disassemble the cylinder and check the O-ring just inside the C-clip. That's where it's leaking from, right? Clean the sealer away, just put a little lube on the O-ring. Make sure there is no rust or corrosion on the gland or the cylinder. There's a lot of pressure and abuse on that side of the cylinder so you want to have everything as perfect as can be. Anytime you are working on a cylinder, think surgical clean. One little piece of dirt can take out a seal or O-ring while assembling a cylinder.

Oh, and Kenny can show this with his super expert JD parts breakdown knowledge, but there is probably a second "back-up" ring behind the O-ring. It would be rectangular shaped and have one side concave for the O-ring to fit in. Anytime you disassemble a cylinder you should change these.

Andy

Andy

 

[bennett2497]

Hi Andy,

The gland is refered to as a ( slip fit gland ) . There is no o ring between the gland and the cylinder barrel and there was not one in the rebuild kit from j.d. ! I did clean it up very well but i think there has to be some kind of sealant that goes on the edge of the gland so when you slide it in it seals around it. We even went down to the local j.d. dealer that i bought the machine from. They said they dont rebuild many and dont know of anything that goes on there. But when we took it apart you could see like a black stain on the bottom of the cylinder tube that shows there was some kind of sealer used. Thanks, Curt

 

[bennett2497]

Hi Andy,

Anything info. you guys can give me is much appriciated ! Since my local dealer cant tell me. I think they send there cylinders out of house to be rebuilt. Thank you , Curt

 

[kennyd]

Curt,

This is a model #7 correct? The #70 is a loader...


There where two types of cylinders used depending on the SN#, Pics posted below.

These are SA (single acting) cylinders, so there should be no oil on the rod side of the piston, if there is-then the piston seals are bad or installed incorrectly.

 

[dfkrug]

Yeah, I can see not having any gland seal if the cyl were single-acting
as on the 7 hoe. The 70A loader cyls use the same kind of circlips to hold
the gland in, but since they are DA, there ARE seals.

 

[bennett2497]

Hi Kenny,

First , thanks for you time. I have a J.D. 855 Loader with a 70A backhoe on it. Its the swing cylinder and it looks like the second picture you sent me . If you notice where the gland meets the cylinder barrel theres no o-ring like the first picture shows. Also theres a cross over tube that goes to the other swing arm and connects down by the gland , so there has to be fluid right in that area. Thats where its leaking , where the gland meets the cylinder barrel. The rest of the seals i just put on the way the old ones came off. It doesnt leak where the seal that goes in the gland against the shaft but between the gland and the barrel. Thanks, Curt

 

[kennyd]

Funny, there is NO reference to a #70a backhoe on the jdparts site, and the 855 is either a CUT or a tracked crawler/loader-so I can only use the #7 parts guide as a reference...

The hose that connects to two cylinders (#16) is a low pressure hose connected with hose clamps correct? There is no way there is supposed to be pressurized oil there...The connecting hose is probably used rather than having a open vent in the rear of the cylinder in such a harsh area. SA cylinders need to be vented somehow on the "other" side of the pressurized area.

I stand by my original statement that the piston seals are damaged or installed incorrectly-sorry.