kobelco sk220 noise when operating boom cylinders

[Steamboat]

I still have problems with the arm hesitating when it gets straight up and down but now when lowering the boom it makes a sound like i have a dry pin(which i dont)Its not a poping noise but more like a dull dragging

 

[grandkobelco]

Check all the clamps that hold the steel tubes to the boom and all the clamps that hold the tubes to the frame. If they become loose you will here vibrations. Do you have a thumb or any other attatchments on the end of your arm? How much delay do you get in the arm? Are you talking about arm all the way out to all the way in wide open throttle? What is your engine rpm at WOT no load.

 

[Steamboat]

Yes it has a thumb on it,running at wot and the arm all the way out bringing it all the way in,probably about a 2 sec delay

 

[ben46a]

Sounds like a line relief/makeup valve. It can't move enough oil to fill the void in the cylinder and it takes a second or two for the pump to make up the difference when the weight of the stick goes over centre. Some cats had a similar issue. The weight of the thumb likely isn't helping either as the added weight will let the stick come in faster than was allowed for during the design stage of the machine.

 

[grandkobelco]

When did you first spot this problem? The reason I ask is I ran into this on the same vintage machine during a routine service inspection a few years back. They also had a thumb and a q-attatch. The operator had never spotted the issue because he had never dropped the arm like that. I Inspected the regen valve, port releif valves, checked cyl drift, Never did fix it. Later on I talked to a kobelco service rep and he stated the larger mark 4's had this issue when the had extra weight on the boom. However there is a regneration spool inside the arm spool that can get sticky or have broken springs.

 

[Steamboat]

I've checked out the arm spool but didn't See anything obvious. From what I've been told the only way to fix a regen valve inside the arm spool is a new spool ???

 

[grandkobelco]

If my memory is any good a few years ago I bought just the regen spool or the spring without the arm spool assembly. But I can't get on kobelco parts this morning, if I get at the shop this afternoon i'll see if I can find it in the parts book. There is a website were you can look up parts but my laptop lost it.

 

[Steamboat]

Where u ever able to locate if u can replace the regen springs in the spool or if u have to replace the whole arm spool

 

[grandkobelco]

No, you have to buy the whole arm spool. I see your talking about week swing also. Arm and swing are mostly a p2 function. If you are in H mode at wot does this machine travel in a straight line for a distance?

 

[Steamboat]

It won't go perfectly straight but doesn't get off line too major

 

[grandkobelco]

The reason I ask is p2 controlls arm, swing, and left hand track, so if you have a flow problem these functions will be affected, Do you have pressure gages to plug into the ports on both pumps?