JD Hydraulic Cylinder Rebuild Help?

[reasley]

Good evening,

I have a JD 4300 and need to rebuild the front end loader cylinders. I have the factory workshop manual for the tractor, but it doesn't have the instructions for the loader and its cylinders. I also have four seal kits.

All I need is to know how to remove the rod from the cylinder. I have attached the parts picture of the cylinder and have removed the external circlip. It doesn't look like anything is holding it in, but I can assure you that it is!

Does anyone have experience with these and can point me in the right direction?

Thanks in advance!

Richard

 

[Wayne County Hose]

Good evening Richard,

#3 looks like a snap ring. Remove it. (I guess you already did.) Lock the cylinder in a vise. Make sure the cylinder is empty of oil. In the vise, point the ports down with a way to catch any oil still in the cylinder. Now, push the rod in. Then, with a slide hammer like action, pull the rod out quickly. You want the piston to hit the gland and knock it out of the housing. Sometimes, they just won't come out. This is when I'll point the rod in a direction so as not to hurt anything. Then, I have a 3/8" ball valve with an air chuck on one end and a #6 JIC female on the other. I attach it to the base end port of the cylinder and open her up. If that still doesn't work, time to chain the base of the cylinder housing to something unmovable, then chain the rod to your drawbar. Let the machine do the work. This last resort had NEVER failed.

Hint, sometimes tapping the gland with a brass punch (#10) then squirting some penetrating oil around the outside of the gland helps. Also, if the slide hammer action won't work, tap the gland in and look for another snap ring. I'm looking at #6 and not really sure what it's function is, but it may be another snap ring.

Hope this helps, Andy.

 

[kennyd]

Here is what I learned when I did mine and had the same problem:

In the seal kit there is a orange plastic piece...in the end of the cylinder there is a groove...Now put the plastic piece in the groove, make sure its flush all the around. Now you can do as Andy said...give it a good YANK!

What is happening is part #6 is expanding and catching in the groove stopping you from pulling out the rod. Drove me crazy also!

When you go to put the new seals on the piston, boil them in water for a while to soften them up. I then wrapped a piece of thin aluminum flashing around the piston and clamped it with a hose clamp while they cooled-but this was probably unnecessary.


Let me know if this helps...

 

[reasley]

Thanks for the replies, Andy and Kenny --

I posted the message right before the family left for the new Indiana Jones movie so I had some time to think about it there. When I took the cylinder off today, it was very hot (outside, not the cylinder) and I had about 20,000 things to do today, so I wasn't really thinking about it. Tonight, I realized that there must be 2 points of resistance: the outside snap ring that I had already removed only prohibits the rod guide from being "sucked into the cylinder" under pressure and does note keep the rod guide from "popping out" under the other direction of pressure -- that part must be the one that I"m missing, right? Kenny, is that what you are referencing when you say "In the seal kit there is a orange plastic piece...in the end of the cylinder there is a groove...Now put the plastic piece in the groove, make sure its flush all the around. Now you can do as Andy said...give it a good YANK!" So, if I'm understanding you correctly, the orange "split ring" that I also saw in my kit is merely a tool to remove the rod assembly, right? So, to use it, I will plunge the rod guide down into the cylinder, put the orange split ring in the groove of the body, and then remove the rod guide and rod assembly, correct?

Thanks in advance!

Richard

 

[kennyd]

Yes Richard, that's it... the split plastic piece is a tool, it fills the groove so that ring (#6) can slide on out of the cylinder body.

 

[reasley]

Yes Richard, that's it... the split plastic piece is a tool, it fills the groove

Logged in as reasley
Title:Re: JD Hydraulic Cylinder Rebuild Help?

Message:​

so that ring (#6) can slide on out of the cylinder body.

Worked like a charm, Kenny -- thanks! Now, I have another problem. When I disassembled all of the seals, guess what? -- the seal kits from John Deere are the wrong ones. My loader number is 013546 and if you look it up in the on-line catalog (search on 420 loader), it lists 10 or so lift cylinders and 10 or so bucket serials -- spec'd by serial number of the loader. Looking at the #10 bucket cylinder, this is the kit that they gave me at the dealership. I had originally looked up #18 bucket cylinder (look at the ordering of cylinders and you'll see why I chose that one). But I didn't order the kits from #18, I let the parts guys look them up, figuring that they would have more accurate data and would be more certain of the right kits. So, when I realized a while ago that the kits are not the right ones, I concluded that #10 must not be the right cylinder and #18 must be. So, I copied down the part number on the cylinders that I have (it is AH166856) to try to match it to the right listing on-line. When I did, I found that it matches the #10 cylinder -- precisely the one that the dealership looked up. But -- the seals are not right! So, looking more closely in #10's part list, there is a previous seal kit (AH167205), but in the notes, it is superceded by the one that they gave me. So -- I guess that the solution to the problem is take one of my cylinders down on Tuesday and go from there? Also, the lift cylinders are listed as using the same kit, so I guess that I need to go ahead and pull one of those in case these kits work on them.

Any additional suggestions appreciated!

 

[kennyd]

HHHMMMMM

This is what I came up with:

First, I only see two different cylinders for the 420 loader listed this way:

Cylinder, Lift(420) (S.N. -013054)
Cylinder, Lift(420) (S.N. 013055-)

Then:
Cylinder, Bucket(420) (S.N. -013054)
Cylinder, Bucket(420) (S.N. 013055-)

Based on your serial # (013546) you would select the second one (because your serial # is after 013055.

From that, you would want part #16:
16 AH176273 HYDRAULIC CYLINDER KIT

I am not sure where you guys are getting the other part #s?

So again, my best guess is AH176273.

Kenny

I will PM you my phone # in case you want to call me about it...

 

[reasley]

Based on your serial # (013546) you would select the second one (because your serial # is after 013055.

From that, you would want part #16:
16 AH176273 HYDRAULIC CYLINDER KIT

I am not sure where you guys are getting the other part #s?

So again, my best guess is AH176273.

Kenny

Good evening, Kenny --

I transposed the serial number but the result is the same, I think. My number is 015346, not 013546 but again, I think the results are the same.

Your numbers above are the same numbers for the kits that I got -- but they are wrong. Weird. Also, I confirmed the kits by matching my cylinder numbers with that particular parts listing -- one and the same. The only thing that I can figure is that JD must have a parts number mistake that is seen both in the consumer parts list and the one that the dealer sees.

I have cleaned my old seals and have them packaged and will try to match them at the dealer tomorrow with any kits that they might have on the shelf. Also, I could probably match them up now at the local hydraulic shop, I guess . . .

Richard

 

[reasley]

. . . Hope this helps, Andy.

Good evening, Andy --

I note that you are in the business.

Prior to this rebuild, I have never been inside a hydraulic cylinder before but I have an extensive mechanical background.

I have looked at my cylinders and parts while waiting to get the right kits (see previous thread messagees) but, even though I have mechanical experience, I could benefit from your experience, if you are willing. Assuming that's the case (and also assuming that this material hasn't been covered already in a previous thread -- if so, kindly redirect), I have a couple of questions:

1. Is there a tolerable level of scoring on the piston? Or, is it a "scored at all, then check the bore, if scored at all, scrap" type thing?

2. I am sure that out of round on these cylinders is not an "eye it" type of thing -- I have a machine shop that can check it for me, if needed. However, going back to Q. 1 -- if there is any scoring evident, is this indicative of either a permanent or momentary bending of the cylinder rod?

Many thanks in advance.

Richard

 

[kennyd]

Richard, is it possible that they are not "wrong" but "different"? Have you tried to install them?

There are updates in parts all the time...Maybe you have the latest and greatest.

 

[reasley]

Richard, is it possible that they are not "wrong" but "different"? Have you tried to install them?

There are updates in parts all the time...Maybe you have the latest and greatest.

Good afternoon, Kenny --

As you know from our phone conversation, this was exactly the situation (thanks!) and I now have two of the cylinders rebuilt; a quick lunch break and I'll finish the others.

When I first compared the seal kits yesterday, I was hot (95 here in Central Texas) and frustrated that I was working at maintaining something instead of being productive getting tasks done -- not a good time to work! The first seal that I compared was the main piston seal and the new one was a completely different design -- no taper, about 4X as thick as the old and was in a separate plastic bag within the kit. I quickly concluded (erroneously) that this must be the wrong kit.

After Kenny's suggestion, I systematically put the old sealsand the new seals side-by-side. There were only two differences: the main piston seal (described above) and a flat plastic type seal that was a different color. Then, I inspected another old piston that had not yet been disassembled and realized that this was the failure component that was causing the leak down. I'll post another message later that has pictures to illustrate the failure and the replacement seal and how it overcomes the old seal's weakness.

Again, Kenny, many thanks for helping out this Memorial Day!

Richard

 

[Wayne County Hose]

1. Is there a tolerable level of scoring on the piston? Or, is it a "scored at all, then check the bore, if scored at all, scrap" type thing?

2. I am sure that out of round on these cylinders is not an "eye it" type of thing -- I have a machine shop that can check it for me, if needed. However, going back to Q. 1 -- if there is any scoring evident, is this indicative of either a permanent or momentary bending of the cylinder rod?

Many thanks in advance.

Richard

Hello Richard,

To answer your questions, i will give you more my opinion than anything else. Hydraulic cylinders are a rather mysterious item that there is not much info on, other than stuff written so only engineers understand it. Perhaps if there were someone with a degree in this field, they could answer better than I. Given that, here is my answres to your questions based solely on my experience.

1. Scoring on the piston is an indicator of your second question, rod flex or bent. When the rod flexes, it cocks the piston in the bore. This causes the piston to scrape the cylinder. Unless it is an aluminum piston, the cylinder bore is also scored. The piston is usually okay, the cylinder bore needs to be inspected by someone knowledgable in the field. It can either be honed or needs to be replaced. Cylinder bores need to have a nice even cross hatch pattern to seal correctly.

2. Any machine shop can check the bores for roundness with a simple bore gauge. They measure the bore at at least 2 points opposite each other and compare the readings. very rarely, if ever, have I seen a hydraulic cylinder out of round. They sometimes have dents, or balloon out to the point of almost bursting. Usually any problem like this is very easy to see. But, checking is never a waste of time.

Good luck, Andy.

 

[reasley]

Hello Richard,
1. Scoring on the piston is an indicator of your second question, rod flex or bent. When the rod flexes, it cocks the piston in the bore. This causes the piston to scrape the cylinder. Unless it is an aluminum piston, the cylinder bore is also scored. The piston is usually okay, the cylinder bore needs to be inspected by someone knowledgable in the field. It can either be honed or needs to be replaced. Cylinder bores need to have a nice even cross hatch pattern to seal correctly.
Good luck, Andy.

Good evening, Andy --

Exquisite timing! I had just downloaded some pictures that I was going to post to this thread when I saw your response. Thanks for the insight!

Though I have already assembled all of the cylinders and installed, the pictures do reveal several things. Looking at the originalpistonseal picture, you can see the base O-ring and a thinner tapered seal. The newpistonseal has the same O-ring but a much thicker non-tapered seal. Looking at originalpistonsealmiked and newpistonsealmiked, the difference in thicknesses is significant. Pictures failedseal1, failedseal2 and failedseal3 show how the too-thin original tapered seal is insufficient to do the job, with the failed seal allowing the underlying O-ring to protrude beyond the tapered seal. Upon disassembly, the O-ring had actually separated and disintegrated.

These pictures are close-up enough that you should be able to see the grooves in piston area that I had mentioned in the earlier post that led to my questions to you . . .

Richard

 

[Wayne County Hose]

Richard,

Sorry for the delayed response. I have been extremely busy recently and will be for a while. I have come to dread weekends.

Very good pics. I am very familiar with your piston seal design. It is a very good design but the one I despise working with the most. It is always such a hard time getting the piston seal (yellow ring) over the piston. I guess now you will just have to wait and see how your cylinder behaves. I have seen things put together and thought "No way will that work." But, many times I shake my head in amazement as it turns out just fine. So, I never say never.

I would extend the rod out all the way and check for any bends. Bending usually occurs in the lower third of the rod. The further the rod is out of the cylinder the weaker it is. It's all geometry. Someone like Larry could explain it much better than I. If the rod is bent, you will notice some scuffing in the chrome at the high point of the bend.

The o-ring underneath the piston seal has a different function than you may think. It really doesn't seal anything. It keeps the piston seal "loaded" against the cylinder wall. It just keeps the piston seal in place, keeping the right amount of tension between the piston and cylinder. You obviously have an updated piston seal configuration in your new kit. I've received many new kits with completely different parts and thought that no way that looks right. But, they fit in there and work well. So now I always try the new kit before I panic.

Good job on your cylinders and let us know how it works out.
Andy.

 

[kennyd]

It is a very good design but the one I despise working with the most. It is always such a hard time getting the piston seal (yellow ring) over the piston.

Andy, Have you tried to boil the seals like I suggested above? Makes them go on easier...

How that the JD850 project comming?

 

[Wayne County Hose]

Andy, Have you tried to boil the seals like I suggested above? Makes them go on easier...

How that the JD850 project comming?

Kenny, with this type of piston seal, I place the seal in a bowl of water and nuke it to about 160 degrees. If it really gives me a hard time, I heat the actual piston to about 130 with a propane torch.

The 820 is almost done. I rushed like an idiot to get it done today. Everything was all hooked up and ready to go at quarter to 5. Fired it up, and oil literally everywhere. The old FEL valve has a cracked body and it was gushing like Old Faithful. I'm going to throw on a log splitter valve tomorrow. I ended up rewiring the dash as mice chewed the wiring, installed an exhaust up past the hood instead of under the floorboard, addad 3 lights and a switch, installed the valve with all new hoses, and made a bracket for the bulkhead mounted qd's. Also changed the starter solenoid which had maybe a couple good starts left in it, and changed the motor oil. Oil change was easy, only 1 quart came out.

 

[kennyd]

Kenny, with this type of piston seal, I place the seal in a bowl of water and nuke it to about 160 degrees. If it really gives me a hard time, I heat the actual piston to about 130 with a propane torch.

The 820 is almost done. I rushed like an idiot to get it done today. Everything was all hooked up and ready to go at quarter to 5. Fired it up, and oil literally everywhere. The old FEL valve has a cracked body and it was gushing like Old Faithful. I'm going to throw on a log splitter valve tomorrow. I ended up rewiring the dash as mice chewed the wiring, installed an exhaust up past the hood instead of under the floorboard, addad 3 lights and a switch, installed the valve with all new hoses, and made a bracket for the bulkhead mounted qd's. Also changed the starter solenoid which had maybe a couple good starts left in it, and changed the motor oil. Oil change was easy, only 1 quart came out.

All that as a favor?

At least you know you have the pressure line hooked up correctly! And now you know why it doesn't have a loader on it anymore

 

[Wayne County Hose]

All that as a favor?

At least you know you have the pressure line hooked up correctly! And now you know why it doesn't have a loader on it anymore

Yep, all as a favor. I guess I'm just a nice guy. Well, the tractor owner is a real good guy and I know should I ever need anything, I know they will be there for me.

 

[Hookblock]

Thanks guys for all the info on this topic I to would have been at this project all night, or worse yet given up and taken it to a dealer. The seal kit 25$, the little woman and I figuring it out with your help is priceless

 

[Reg]

I re-built a 5 inch diameter log splitter cylinder WITHOUT the benefit of a snap ring groove filler.
That is to say without one from a kit.
First I pushed the end seal IN a few inches to get some working clearance.
Then I improvised by filling the groove with some of that quick set epoxy body putty, filed it fairly flat once it set.
I left it in while I took the end seal and old piston out, replaced the piston "rings" got the piston back, then the end seal back and pushed in a few extra inches.
Then I chipped it out, which didn't take much because I had left the surface a bit oily so it wouldn't stick too well.
The end seal comes back against the snap ring easily enough, just pull on the rod.