I am having issues with the lower crank case vent filling the breather storage tank with oil which fills up and runs out thru the air box.
I was told that there were two things that could be the problem: 1)too much oil...not the problem.(2) bad ring or rings...not the problem either...any other ideas would be appreciated.

 

im also having this problem or (was) i just bought my 99 300ex yesterday and it is smoking after oil change and i looked at the air breather box and the filter is covered in oil and the oil reservoir tank that feeds into the air intake has some oil in it and my intake tube is caked in dried up and wet oil, so i dont know if it was flipped rolled or something major is wrong with the engine,

 

Too much oil in the box would have to be caused by more than normal crankcase pressure. That could be caused by worn piston rings, or a worn cylinder wall. I can't remember if they have more than one breather hose, but you might want to check into that as well.

My airbox doesn't get oil into it, but I know it burns a little oil after doing long wheelies. Just a little puff of smoke.

 

I know this is odd. My son has a 2005 400ex and doesnt have this problem. I have within the last two days rebuilt the upper end w/440 bigbore kit. prior to this I was having the same problem. And are still having the same probs.

 

I would really double check for a clogged crankcase vent tube. There is a reason for the higher pressure in the case, and that's probably why it is getting oil in the box.

 

Driftin, Thanks for the info. I will check the vent tube. I wouldnt have thought it was blocked because the oil flows thru it so easily. Thanks again