Bobcat 520 Relief value/Filter

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Jan 3, 2005
By the subject line you know that I have a bobcat 520. The problem is that when it heats up. The controls for motion go dead. I can lift the bucket but can not move. I turn it off and hear gurgling noise and let set for a while and the controls start to work and move better then they've ever worked before. I have replaced the hydraulic fluid even used bobcat oil. Sucked out every drop that I could. I'm thinking that it could be the relief value sticking or some type of filter plugged.. This only happens when it gets heated up. Thanks


Staff member
Dec 7, 2004
It won't be your relief valve if your hydraulics still work 100%. It sounds like a blocked filter in your hydrostatic system. I'm not too sure about this machine, but i suspect it is clost to my 731, there is a hidden brinze filter in the charge line going to the hydrostatic pump. Lift the cab off, there should be like a square block sitting on the hydsraulic pump with like 5 hoses atached. On the left side there should be 3 hoses, remove the moddle one, it has a larger nut on the fitting, there should be a filter behind this, give it a GOOD clean or replace it.
Like i said, this is where it is on my 731, i am un-sure about your 520. If you have a parts manual, have a look at that section and see if there is a part hidden in that block.
If the machine squeels like a stuck pig when warm, it sounds like thats your problem (mine did the exact same thing when it got warm).