I have to split my Jinma 284

[mrmikey]

I will still have to split the tractor.

Unfortunately yes. 'Bout the only thing you can do in that area without splitting the tractor is adjust the clutch.
When you do get around to it, there's some other things to look at while you're in there, running hours dependant of course. Clutch, throwout bearing, pilot bearing, rollpins in the throwout bearing shaft. Other than the clutch, none of witch are expensive.
Be sure to keep us posted when you start.....Mike

 

[gears]

If it's the same configuration as mine and I think it is, there's a possability it could be the cam shaft plug if you're leaning toward it not being the rear main seal. The plug is exactly like a welch plug and it's just pressed into the hole that the camshaft goes thru.
If you take off the loader mounts off the bellhousing, you can get a better look with a light and mirror thru the square hole. If you look on my post where I was working on mine, you'll see the plug that I've stuck a sheet metal screw in ready to pull out.
You're sure it's lube oil and not trans fluid? I'm not sure of the possabilities of this but it might (and I use the term 'might') be possable for the trans oil to come thru a bad seal. If someone tells you it's not possable, believe them instead of me ......Mike

My 284 also had a severe oil leak. It was coming from the gasket between the motor and the bell housing. That is why the clutch is not affected. Tractors with loaders are prone to that problem. It puts stress on the joint. You must split the tractor, remove the clutch pack, flywheel, and motor side of the bell housing to replace the gasket. Most people replace the pilot bearing, (mine had already had some of the ball bearings missing), the throwout bearing, clutch discs, and all the oil seals at the same time.