Mtl 16 bucket and attachment problem

[Nickbarber47933]

I have a 2006 Mustang mtl16. I recently bought a stump grinder for the loader and everything was going well. And then one day the grinder started having a hard time cutting before gradually getting so weak it wouldn't even cut under no pressure, within 15 minutes or so. I let it cool and a few minutes later it appeared to come back a little bit before dying off within a minute or two. Talked to a few people, replaced the pilot filter and implement pump and no change. Still so weak dirt will stop the blade and the bucket won't raise without idling up. The bucket used to lift pretty good at idle. Had a mechanic come out and diagnosed the bucket level valve to be the issue. He said the valve was scored internally and the spool was sticking open. He bypassed the valve. I tried using it and no change. Does anyone have any ideas what would be causing this? I tried to find the relief valve and I don't know where it is

 

[Tazza]

That sounds like the hydraulic pump is damaged, when cold, the oil is thicker and you can build up more pressure, when hot it get thinner and by-passes.
A good test would be to hook up a 3,000 PSI pressure gauge to an aux coupler then activate it, see what pressure you get. You should get 2,500-3,000 PSI i'd guess.
A dealer can give it a propper test, they load the pump down and measure flow at a set pressure to know if it is indeed bad or not.