Case 621c hydraulic problems

[OH02SVT]

Looking for some help boss bought this machine sight unseen

biggest problem with it is the hydraulics both steering and bucket functions are weak and pump sounds like it's cavitating

Replaced pump same thing happens

Replaced main relief valve same thing

Can't raise bucket empty without giving throttle and still sounds like pump is cavitating same with steering have to be moving to make full turn and you can hear the loud grinding like the pump cavitating

Can't lift a full bucket of material unless you put it to the floor and sometimes deadheading the steering helps it

Put a gauge on the pump test ports can't even get 1000psi

What next to check on this thing it sounds like it's going over relief as soon as you hit any function but I don't know what would cause that any help is appreciated

 

[mg2361]

Welcome to HEF OH02SVT! I'm sure the Case guys will chime in soon.

 

[alrman]

When you say you replaced the hydraulic pump & main relief valve - were these new items? Second hand? Borrowed from another similar machine?

Sure hydraulic oil viscosity is correct?
Could the screen in the tank be restricted?

 

[Coy Lancaster]

If you are hearing cavitation even with a new pump I would check the suction screen in the tank and the suction hose going to the pump.

 

[Vetech63]

Welcome to HEF OH02SVT! I'm sure the Case guys will chime in soon.

If it is cavitating that bad you may see air bubbles in the hydraulic tank oil.

 

[OH02SVT]

When you say you replaced the hydraulic pump & main relief valve - were these new items? Second hand? Borrowed from another similar machine?

Sure hydraulic oil viscosity is correct?
Could the screen in the tank be restricted?

Sorry I didn't get any notification that anyone replied

both hydraulic pumps were known good used and the main relief was brand new from case

I did check intake hose when the pump was off as well as screen in the tank both were good

The screen however is a mesh filter was thinking about taking it off completely and see what happens

 

[OH02SVT]

If it is cavitating that bad you may see air bubbles in the hydraulic tank oil.

No air bubbles in tank I've checked multiple times

It sounds like cavitating or the main relief popping off

I was also wondering if maybe the accumulators were bad and taking all the flow away from the pump