J.D. 690c leaking oil through final drive ( propel motor) air vent ( breather). Replaced breather. Still leaking. Anyone have knowledge of what would cause this problem?
If you're talking about the relief fitting between the drive motor and the gear case, then you have a blown brake seal or motor shaft seal. Reseal both while you're in there, but most likely brake seals I would think. I'd do both sides if it was me. I'm guessing the gear case and planet hub are full to the top with hydraulic oil then? Drain overnight and refill to level with whatever Deere sez, probably 90W? Make sure you drain the planet hub also, should be a plug on the outside of the hub. After reassembly turn the sprocket hub until the drain hole is level with the middle, make sure the oil level in the planet and the gear case are up to snuff, they share oil but it's best to insure both sides are actually full after draining.