John Deere 4300 complete rebuild

[dfkrug]

OK, I am not done yet!

I got all my hoses and fittings to refurbish my loader, and it is all hooked up.

There are 12 hoses...I replaced all but one.

Well, first the good news: the loader frame is really tight, and the QA
bucket does not wiggle either. What a difference.

Now the bad news: After I got the hoses all connected correctly (took
a few tries), I can barely lift the loader boom into the air! And sometimes
not at all! I can see the hoses are passing fluid, so the QA fittings are OK.
Once I do get the loader bucket a few feet off the ground, releasing the
valve keeps it there, so the valve is OK. So, that must mean one or both
piston seals are bad---really bad. Chances are its just one, so which one?

What I did was operate the valve at 2/3 full engine speed, where it could
not lift the boom any higher. I took my handy HF laser thermometer and
monitored temps of both boom cyls just after the piston. Hyd oil gets
hot fast if you squirt it thru holes at high pressure and volume.

It was my right hand one. You can see the plastic piston seal in these
pix...it is red-orange, unlike the black one from the cyl I rebuilt much
earlier in this thread. This medium hard plastic was very worn, more on
one side than the other.

If you look closely, you can also see my retaining wire. The end
hook that anchors it into the gland it broken off, so I had to pull it out.
The broken tip is in the hole. I have not decided yet if I drill a new hole,
drill the wire out, or put it together as-is, with no anchor hook.

The saga continues.

 

[dcyrilc]

OK, I am not done yet!

I got all my hoses and fittings to refurbish my loader, and it is all hooked up.

There are 12 hoses...I replaced all but one.

Well, first the good news: the loader frame is really tight, and the QA
bucket does not wiggle either. What a difference.

Now the bad news: After I got the hoses all connected correctly (took
a few tries), I can barely lift the loader boom into the air! And sometimes
not at all! I can see the hoses are passing fluid, so the QA fittings are OK.
Once I do get the loader bucket a few feet off the ground, releasing the
valve keeps it there, so the valve is OK. So, that must mean one or both
piston seals are bad---really bad. Chances are its just one, so which one?

What I did was operate the valve at 2/3 full engine speed, where it could
not lift the boom any higher. I took my handy HF laser thermometer and
monitored temps of both boom cyls just after the piston. Hyd oil gets
hot fast if you squirt it thru holes at high pressure and volume.

It was my right hand one. You can see the plastic piston seal in these
pix...it is red-orange, unlike the black one from the cyl I rebuilt much
earlier in this thread. This medium hard plastic was very worn, more on
one side than the other.

If you look closely, you can also see my retaining wire. The end
hook that anchors it into the gland it broken off, so I had to pull it out.
The broken tip is in the hole. I have not decided yet if I drill a new hole,
drill the wire out, or put it together as-is, with no anchor hook.

The saga continues.

Not sure exactly how it anchors in the hole, but any chance you can use compressed air in the hole to try to dislodge the wire tip enough to get a hold of it with needlenose or something?

 

[dfkrug]

Not sure exactly how it anchors in the hole, but any chance you can use compressed air in the hole to try to dislodge the wire tip enough to get a hold of it with needlenose or something?

The retaining wire has a short 90-deg dogleg in the end of it. It goes
into a tiny hole. I suspect these get broken when the person working
on the cyl turns the gland too far.

As for easily getting the broken piece out of the hole....no luck so far.
This wire is about 1mm in diameter and, I suspect, hardened.

JD has both wire-retained and snap ring-retained glands on the cyls for
this, and other related FELs.

 

[kennyd]

Neat way to determine which cylinder is bypassing D, but I am a firm believer that they should be rebuilt in pairs...

 

[Kyle_in_Tex]

What about a strong magnet? I wish I could see the situation myself so I could maybe offer help. Also, thanks for the idea on trouble shooting. I would agree with Kenny, just like disc brake calipers on the front end of a vehicle, replace in pairs so you get equal action hopefully.

 

[Kyle_in_Tex]

Spring steel can range from hard to very hard. What about a dremel with a carbide burr tip? An accurately aligned and held carbide drill with a very light feed may get it out unless it spins in the hole.

 

[dfkrug]

Spring steel can range from hard to very hard. What about a dremel with a carbide burr tip? An accurately aligned and held carbide drill with a very light feed may get it out unless it spins in the hole.

That's a good suggestion. I have not tried that yet, and I have many
of those tiny all-carbide bits. I don't use them very often, so I did not think
of them.

Kenny: as for changing the piston seals in pairs, I would do that if it was my
own personal tractor, or I knew its history. It is likely that both boom
cyls on the same tractor endured the same conditions. For most tractors.

This machine, however, was a rental machine, and the cyls are swapped
around for other 4300s' in the inventory. Furthermore, this cyl has
already been repaired at least once....I can tell since the rod-end cross-
tube is not painted. I know the hydraulic shop that does the work. I
also suspect the piston seal is an aftermarket teflon seal, not the black
nitrile seal I saw on the other unrepaired cylinder. Finally, the part #
etched on the outside of the cyl does not come up in the JD database,
and is different from all the part #s of cyls for any 420 FEL. So even tho
I can order seals separately from JD, I have no idea which cylinder I have.
"Nuff said?

BTW, I can get the seal from HB in teflon for $13.

 

[monsternash]

This rebuild thread is just teriffic. Thanks for sharing.

I have a question you should be supremely qualified at this point to answer: How does the coolant overflow bottle attach? It looks like it is bolted to the side of the fuel tank. Mine (on a 4200) is broken somewhere on the bottom. I got in there and cranked on the bolt that seems to be holding it on but it never deemed to loosen. Anyway I was hoping maybe you could clue me into what I need to know while I wait for the manual to arrive...

 

[arrabil]

Go to JDParts, create an account, and get the parts pictures. Might be the easiest way to figure that out.

 

[dfkrug]

How does the coolant overflow bottle attach? It looks like it is bolted to the side of the fuel tank. Mine (on a 4200) is broken somewhere on the bottom. I got in there and cranked on the bolt that seems to be holding it on but it never deemed to loosen.

There is a threaded brass nut that is pressed into the side of the
polyethylene fuel tank. It sounds like it pulled out or got stripped. Not
good.