Question about plug on rotary rotary mower

[AlbertC]

My bushog rotary mower is still leaking oil where the pto goes into the gearbox. It looked like it needed oil so I added some and it seemed to leak worse than ever when I used it to cut about 2hours today.

Does anyone know if the plug on the top of the gearbox is supposed to maintain a certain pressure within the gear box or not? I took the plug out and tried to blow air through it by holding it to my mouth and blowing and I could not blow air through it, but when I tried to blow it with my air compressor I could tell air was going thru the plug.
So, I am wondering is my plug defective since I can only get air to pass through it with the air compressor.
Some respondents to my earlier question about this said the if I shake the plug I should hear it rattle.,my plug does not rattle when I shake it.

If the plug is supposed to pass air through without pressure, I am wondering if pressure is building up in the gearbox and forcing air thru the seal. Don't know if since it seems to be leaking worse than ever if it means my seal is now destroyed and needing replacement

Anybody have any input?

Thanks

 

[Coyote machine]

Pictures of the leaking area would be helpful. Also the plug you refer to, is it an actual gear case vent?
In general a gear case would need some kind of vent to release built up pressure from the gear oil heating up and expanding during use.
A leak from something like a seal or gasket is going to leak from the path of least resistance and at the lowest point where fluid can leak out. Sounds like that place is the front seal where the input shaft enters the gear box.
If you've filled the gear box to just above the side plug opening then it's full filling the box completely is going to create too much pressure, and the expansion is going to force something to give. Sounds like, if you overfilled it, and now it's leaking worse that's your indication the seal or vent is failed or not working, in that order. Hard to tell from my house, since I don't know year or model # and don't have any pics to tell what's happening.:confused2:

 

[Fallon]

If a vent doesnt pass any air, it's not much of a vent. Doesnt need to pass much or very quickly. But if it's not venting it will blow out your seals when it heats up or pressure changes. Might try soaking it in some solvent to see if you can clean it up. If not, replace it ASAP.

Changing out the gear oil to pourable grease will usually fix the leaking. Minimal downside, but the better way is replacing the leaking seals.

 

[Beltzington]

"If you've filled the gear box to just above the side plug opening then it's full filling"

Found this out the hard way, assumed the gears should be covered with oil and it leaked out of the top plug that on my RC is actually a vent. Looked it up in the manual and it says to fill until oil just runs out of the side hole. Because the side hole is so small it really easy to overfill if you do not remove to cover and visually fill to the hole. There is really very little gear oil in the actual gear case just enough so the bottom of the vertical gear is covered.

My vent will let air pass in either direction and once I figured out it was a vent I found out it was plugged up and needed to be cleaned.

Good Luck!