Did I over fill it?

[agood1]

Or is is there something else wrong?

This is after I ran it a while and it got hot.

[TheOldMan]

I don't know who drilled the vent hole in the plug. My 580C doesn't have one. I would guess that the tank vent is plugged. On top of the tank cover, to the right of the gas filler neck, you'll see a snap plug. Pry it up, and underneath is the vent for the hydraulic tank.

[agood1]

Is this the vent you are talking about? If so, it appears to have a spring loaded valve in it.

[TheOldMan]

I'm not sure. I never looked at mine, because I never had trouble with it, only read about it. If you look on page 244 of the parts manual, you'll see that there are two "relief valves", an inlet and an outlet. I'm assuming that this to to vent the tank for either over pressure or lack of pressure (vacuum). We all know that as you heat a liquid it expands. If the hyd fluid in the tank expands, it would either have to vent somewhere or compress the air that is in the void in the top of the tank. When you fill the tank up to the sight glass, there is still a significant void in the top of the tank on both sides. My 580C has a plug with a 3/4 square detent. Your pix shows a male
square to remove the plug. Mine is not vented, and yours is, so theres a significant difference somewhere - maybe one of the more experienced guys will chip in here.

[Andre Grondin]

Maybe a rusty plug and now it is leaking at a weak spot !

[agood1]

Don't think so, the plug is in good shape all around, and the hole is to perfect to be rusted.....it was definitely drilled. I thought it was supposed to be there.

[TheOldMan]

I just refilled the hydro reservoir on mine today, because I had drained it to remove the pump. Mine has and inverted pipe plug, and there is no vent hole in it. I think someone in the past has changed and vented your plug.

[sheepfoot]

Place loader bucket flat on the ground, raise stab cylinders up, place the backhoe in the transport lock, oil level should be in the center of the site glass. drain out extra oil in hyd tank and clean breather, should be good to go, the plug should not have a hole in it, some one removed it with the vent stuck before and it went across the shop so they drilled a hole so there would be no back pressure, have fixed several before where the owners did this instead of cleaning the breather.

[agood1]

Where is the breather?

[sheepfoot]

agood1, they are over the fuel tank in the top uprights, there is two, LH side is a outlet valve and the RH side is the inlet valve, there is a 1/4 hose that runs between them also, both sides of the machine frame feed the hyd pump, the valves and crossover hose help maintain the system by both letting air in and pressure out.

[bowen]

Where is the breather?

Mine is a 580SE, and my vents are under the cover for the fuel tank up top on the right side.
Look at the lower right of the photo underneath the multimeter.
I was up on the machine to the left of the steering wheel to take this picture as I was working on the fuel level sender.

I think one lets air in and the other air out.

[agood1]

Hhmmm, I'll have to take some more pictures....cause I think mine is different. The valve I pictued above is in a "T" fitting that is in a line that runs between the 2 tanks.......I think pictures will better describe it.

[sheepfoot]

agood1, the case 580D/E machines have the single vents, the silver looking one is the inlet and the black looking one is outlet. the C was differant with the tee's and cross over line.