2002 Cat 420D IT ?

[NCman]

Thanks for the information. Today while using it the dipper moved straight out on its own and would not retract until I turned off the key and relieved pressure. Does that still point to a bad cylinder?

 

[AllDodge]

I would think the spool valve would need adjusting, but these others guys are more of then expert

Have you checked your fluid level (level ground, buck flat and down, riggers up, boom up and bucket tucked in)?

 

[NCman]

Yep. And fluid right at full mark.

 

[Mark250]

you could have residual pilot pressure acting on the end of the spool
does the joystick feel looser than normal, if so the pilot control valve plungers may be sticking or if the control is not adjusted properly it could be holding the plunger down and allowing pilot oil to the stick spool.
it is also possible that a spool centring spring has failed in some way
Mark

 

[koecon]

Did it sound like there was a load on the engine before you turned it off? How did you release the pressure? When restarted did the stick work normally or did it drift out?

 

[NCman]

I relieved pressure by not cranking but just turning the key and actuating all controls in each direction. After doing that the dipper/stick started to fall from the fully extended position. I have someone that wants to rebuild the cylinder Monday. I'd hate to rebuild the cylinder and find out it's something else. As far as hoe pilot control, it does feel a little different than my right side control. Occasionally, over the last 50 hours, the left pilot control would bind a little when pushing forward to raise or lower the stick. My main problem has been the stick drifting, but like I mentioned yesterday, the stick extended on its own and would not come down until I relieved pressure. Any further ideas or guesses to what would cause that malfunction would be greatly appreciated. Thanks again.

 

[koecon]

I thought the stick cylinder rod moved out by itself but your saying the stick moved all the way out by itself? That's not a cylinder problem! It's a valve issue and by the description I suspect it's the pilot valve (joystick)

 

[NCman]

some letters are not working on my keyboard so first off...my apologies.
I was working yesterday and all of the sudden the stick/dipper fully extended on its own. Before tat my main problem was the stick drifting down,
If I move the pilot control forward just a tad ten the dipper will not rise or fall. If I let it free ten it will usually drop all the way down,
,

 

[AllDodge]

I'm still thinking pilot control adjustment or valve body leaking

 

[koecon]

That sounds like a pilot valve (joystick) problem to me!

 

[NCman]

Been using the last few days. Recently I was mad at the 420 for not working properly and the dipper dropping so I slammed the throttle up to a max of 20-21 and started yanking the pilot control in all directions. It started working properly and now if it acts up I just repeat my tantrum and it obeys.

Any comments as to more throttle and joystick manipulation solves the issue?

I appreciate all the help.

 

[AllDodge]

I think the problem is in the joy stick, its hanging. Working it like that frees it up for a bit

 

[NCman]

Yes, it sure seems like it. I've got a guy coming to look at it this week so hopefully we will figure it out. I'll update with the outcome.