7308 loader won't hold curl

[larpai]

I purchased a used TC33D with loader about a month ago. After about 10 hrs. use, the bucket will now slowly uncurl on its own. Lifts fine, curls fine and dumps fine, just won't hold the curl. I constantly have to keep hitting the lever to keep the load from dumping on its own.
Any advice is much appreciated.

Thanks Larry

 

[CalG]

the directional control valve is allowing flow back to tank.

Something inside is amiss.

Does the valve provide regeneration function?

 

[larpai]

I understand small engines and cars but hydraulics is new to me. What is "regeneration function"??

 

[CalG]

Regeneration directs the fluid flow out of the compressing side of the hydraulic piston into the extending side of the same piston.

This has the effect of Speeding up the extending function. It is often used to speed up the dump cycle of a bucket. Exactly your situation.

Still, The DCV is at fault. It will need to come apart for inspection. Might just need cleaning.....or a spring or something

 

[Tx Jim]

Problem could also be a leaking bucket cylinder piston seal or both cyl piston seals.

 

[Gary Fowler]

It could be the cylinder bypassing but my money is on the control valve leaking by. Replace or rebuilt it and your problem should go away

 

[Tx Jim]

It could be the cylinder bypassing but my money is on the control valve leaking by. Replace or rebuilt it and your problem should go away

I've seen more cyl piston packings fail than control valves fail. If it was my loader I'd check the cylinders for internal leakage.

 

[brain55]

I've seen more cyl piston packings fail than control valves fail. If it was my loader I'd check the cylinders for internal leakage.

I agree. Way more cylinder packings than control valves. In my over 25 years working on CUT's I can count on one hand the number of controls valves I've seen fail and have long since lost count of cylinders I've repacked.

Brian

 

[CalG]

If the cylinder packings are at fault, there will be hydraulic fluid dripping on the ground where they are leaking. The rod displacement needs to go somewhere. If it can't get back to tank, the bucket is not going to droop.
If there is no external leakage, the leakage must be internal, and MUST return to tank to allow bucket droop. Fluid just passing the cylinder piston won't do it.
Very easy diagnosis.

It is possible that the spool valve leaks between bucket and lift arm cylinders, with the bucket drooping as the arms lift. But the fix is the same. The DCV needs attention.

 

[whitetiger]

If the cylinder packings are at fault, there will be hydraulic fluid dripping on the ground where they are leaking. The rod displacement needs to go somewhere. If it can't get back to tank, the bucket is not going to droop.
If there is no external leakage, the leakage must be internal, and MUST return to tank to allow bucket droop. Fluid just passing the cylinder piston won't do it.
Very easy diagnosis.

It is possible that the spool valve leaks between bucket and lift arm cylinders, with the bucket drooping as the arms lift. But the fix is the same. The DCV needs attention.

One or both of the cylinders is leaking around the piston seals. As oil leaks past the seals it allows the rods to extend out further allowing more room for more oil in the butt end of the cylinder. I would bet he can raise his loader off the ground, curl bucket back, unplugged his hoses from the tractor and it will still uncurl.
Very easy diagnosis...........