753 lift and tilt

I have a Bobcat 753. It had some sort of glue put in the hydraulic tank. I got it from the guy that had the problem. The control valve was out of it and in pieces. I checked the both filters and they were plugged with the stuff. replaced both and cleaned out most of the hoses. wasn't much if anything in them. Pulled the tank and it had what looked like epoxy in the bottom. Both filters had the same stuff on them. cleaned and put the control valve back together and put new filters in. Ran it for twenty minutes or so and replaced filters. The filter in the back had maybe ten percent of the stuff in it. The little one was clean. worked ok for an hour or so then started having trouble with the lift and tilt. They work fine when the machine is cold but in a few minutes they start to slow down and not respond. Let it cool for a day and they work again for a few minutes. Drives work great Moves right out, steers great. replaced Hydraulic pump for lift. I think it is called the sprag pump. Same problem. Any ideas. Maybe pull main control valve and rebuild it? put a photo of first filter on for grins and giggles

that looks bad, hopefully that will clean up in time, do you know why that stuff was placed in the system ?

I don't think he knew something had been put in the system. He said it quit moving and the lift and tilt quit working also. He did not have the knowledge or tools to fix it. He had the Bobcat dealer look at it but when he found out what they wanted to fix it he put it up for sale.

A few months later and I have it fixed. I talked to someone who knew what happened. An employee of the former owner poured some type of concrete additive in the hydraulic tank. Guess he was angry. Anyway it solidified and plugged up the filters. I ended up taking most of the hoses off and cleaning the junk out of them. The stuff was soft. You could crumble it with your fingers so I figured what was left in the system could not hurt any of the steel gears in the drives and pumps. It got soft and sticky if you warmed up the oil so I just would run it a few minutes every day and left it out in the cold.Montana Then just changed the filters every few hours for six cycles.. Cut the filters apart to see how much they were catching. Less each time. Last set there was no contamination. Now I think he knew but refrained from telling me so I would buy it.