JD 300cx bucket slowly dumps by itself

[woodcrosscut]

Hello...I have a JD 3320 tractor with a 300cx loader and the problem I have is the bucket drops slowly by itself into the dump position I have to keep bringing it up. There is no fluid loss. I have switched the lines between the dump mode and the lift mode and it still drops slowly. I believe I have an internal leak in one or both cylinders and purchased two rebuild kits from the dealer. My problem is taking the cyl. apart to replace the seals. there is a snap ring which is easily removed but I fail to see the next step .Is the cyl. piston press fitted or screwed into the housing ? All help and suggestions are very much welcomed. the tractor is a 2006 model.300cx

 

[kennyd]

Read this thread and see if it helps: JD Hydraulic Cylinder Rebuild Help? - TractorByNet.com

The orange plastic thing in the seal kit is the "tool" you use to take the cylinder apart.

 

[leonz]

Before you get any further...................


You need the parts diagram for the cylinders
before you do anything.


I am both surprised and dissappointed that your dealer
did not want you to bring the cylinders in to have them
tested for bypass.


You can save your self a lot grief by taking
the cylinders off and having them pressure
tested by a hydraulic repair shop as 9 times
out of ten the valve is bad leaking back to tank.


The weight of the bucket can and will cause the
cylinders to drop and fully when elevated but as
I said the spool valve may be the culprit and testing
the cylinders will tell you if it is the problem.


The valve spools have a very close tolerance fit and
once they get a bit worn oil is like electricity, its lazy
and it will go anywhere.


Have the cylinders pressure tested for bypass and
then you can proceed and they can repair them quickly
if needed but most likely the valve is the real culprit
is the bucket control spool as it is the most used
valve of the two.


_________________________________________________________________
Once you go flail you never go back:thumbsup::licking::drool:

 

[kennyd]

Before you get any further...................


You need the parts diagram for the cylinders
before you do anything.

All posted in the thread I referenced The JD cylinders are well known for leaking internally-and he already bought the seal kits.

 

[J_J]

My thoughts here is that if you think the piston seals are leaking , then raise the bucket to max up, and shut engine off. If the cyl are leaking, they will equalize and stop moving at some point, and not fully collapse. If the cyl continues to descend, then the valve spools are leaking.

If the valve is leaking, it will provide a path for the fluid until the bucket is on the ground.

With the lift arms raised, one could determine if the spools were leaking by removing the hose from the OUT port and see if any fluid comes out of this port. If you think the fluid is leaking to the main gallery, remove the PB hose, and see if any fluid comes out. The fluid could theoretically leak out both ports, due to worn spools.

You could do a static drip test with the hoses off.

 

[woodcrosscut]

Thanks to all for your help. This morning I removed both cyl 's from the loader and took them to a repair shop. After sizing up the situation removing the snap ring placing the unit ia a very sturdy vice giving the unit several slide hammer type shots and seeing not an inkling of movement I knew it was time to give it to the the folks who do this type of thing every day. This is an unusual move on my part but I am getting older and maybe a little wiser.
On the lighter side I was very happy to find and join this group I was very impressed with the vast amount of knowledge and to find others who love their tractors as I do.
Thanks Again

 

[J_J]

Did you ask them to test the cyl or just change out the seals?

 

[kennyd]

After sizing up the situation removing the snap ring placing the unit ia a very sturdy vice giving the unit several slide hammer type shots and seeing not an inkling of movement I knew it was time to give it to the the folks who do this type of thing every day.

Did you get he seal kits, and install the orange plastic ring that I talked about in the other thread?

 

[J_J]

Was just wondering if the cyl's turned out to be the cause of your problem. Please let us know the results.

 

[woodcrosscut]

Hello again.........The cyl's have just come back from the rebuild shop and are now back on the tractor and all is WELL
Thanks Again to all for your help and support

What a great web site......Your the best