When it was last shut down, was the FEL still in the air? If the FEL was lowered without the engine running, this could be why the resovoir is overfilled. With the hyd pump providing pressure/flow, the flow in and out of the resovoir is about the same regardless of what hydraulic operation is being performed. The only difference is the ammount of fluid displaced by the rods in the cylinders. If the FEL was lowered without the engine running, gravity forced the fluid in the non-rod end of the cylinders back to the resovoir. While the FEL is descending, the rod end of the cylinders will try and draw fluid into themselvs like a syringe. Unfortunatly if there is any kind of leakage between the resovoir and the cylinder, they will suck air instead of drawing fluid from the resovoir. It is much easier to suck air in through a leak, than fluid through the line, particularly if it still has the thick Chinese motor oil in the hydraulic system. Once there is air in the system, those bubbles will also expand in a vacume without drawing fluid from the resovoir. This can easilly result in a resovoir overflow.
I would suggest that you go over all the hyd fittings in the system with a wrench to make sure they are tight. My 284 was delivered with the suction fitting at the resovoir loose so it was sucking air while it ran, making the hydraulics a little "jumpy" due to the steady stream of bubbles in the system. Air bubbles in the system also cause cavitation in the pump which is hard on it.
After everything is tight, Start up the tractor and cycle all cylinders several times in several positions. Try to cycle the dump and grappel cylinders with the rods pointed both up and down to purge as much air from the system as possible. Allow them to set at their limits for a little bit between cycles to allow any air bubbles to migrate to the top near the fitting so they will be the first out and be pushed all the way back through the hoses and spool valve and on to the resovoir. After this put the FEL back solidly on the ground, then shut the engine off and go check the resovoir level. You might be pleassantly surprised
If it is still full after that, I would say the dealer overfilled it. The level should be in the vicinity of that mark on the dipstick. If you are worried about overflowing while cycling the system, connect a hose to the vent pipe and run it into a container to catch any potential overflow.
I wasn't real pleased having the vent on the filler cap on my 284. It placed the actual vent point at the bottom of the threaded cap on the dipstick(down inside the resovoir). Being all the way back in the resovoir, this sometimes causes a small overflow when cycling the hydraulics while the front of the tractor is elevated, such as dumping a load on top of a brush/burn pile. I drilled and tapped a 1/4 NPT hole in the top of the resovoir up between the forward seat mounts. This is about the highest point in the resovoir and nearly in the middle. I threaded a hose barb into this hole and run a hose to a filter with dessicant in it up on the seat back. I do this to keep dirt out of the system and to keep the air dry and cut down on condensation that will contaminate the oil. I converted the filler cap into a hydraulic return port with quick connect fitting pointing toward the rear.
