Finish mower gearbox oil

[RunninOnEmpty]

I recently picked up a pre-owned 60" finish mower. I'm not sure of the brand & there's no markings indicating it's make.
The mower cuts fine, but noticed (after running a while) oil seeping out of fill cap on top. I unscrewed the cap & noticed the oil is filled nearly to the top.Is gearbox filled too much?

 

[greg_g]

Overfilled for sure, but it could be water too. Gear oil + water + agitation + friction = a bubbly emulsion that expands as it heats. I recommend draining what's in there, flushing with kerosene, and a fresh fill with 90W gear oil

//greg//

 

[JimRB]

Generally you fill the case halfway or to the oil level plug that is about halfway up the gearbox. If I had time I would run out and take pictures of my three gearboxes. If you were to find the drain hole you would drain when hot meaning after you mowed for a half hour on a warm day. When you refill you need to double check the oil level as it could take time for the oil to flow back in between bearings and gears. If it were my mower I would get my MityVac out and suck some of the excess oil out.

If you post a picture of the mower someone may help you identify the brand.

You may be able to find some mower info on line. Bushog does not go in to great detail on oil level in this manual. A gearbox is a gearbox. http://www.bushhog.com/images/stories/documents/manuals/RZ160.pdf

 

[RunninOnEmpty]

Your explanation is spot on, when I checked the oil I noticed tiny bubbles on top. I'll be sure to drain, clean & refill.
Should I fill gearbox to 3/4 again?

 

[Oliver1655]

If there is a fill hole on the side, fill it up to the fill hole. Gear boxes are frequently designed this way to prevent over filling. If the fill hole is on the top, fill until half of the gears are covered.

 

[RunninOnEmpty]

Thru extensive research I was able to find the manuf. of the mower. It is a Rotomec 60" side discharge. I checked & the gearbox does not have a side fill hole, but on top.
I will have to syphon oil & replace, filling until half of the gears are covered (as recommended above). Thanks!