Working on a 2001 fat-boy. Bike motor has been modified a lot. I think it is a 107 with screaming eagle heads and has 258 cams. When the bike was brought to me it was knocking bad in the cam area. when I took the nose cone off and took out the cam plate, could not get the lifters to move freely up and down. just by there self. had to hone out the lifter holes where they were rough. There was also signs of oil coming out the breather through the breather tube. I replaced all the "o" rings and gaskets and got the bike fired back up. Running smooth for a few min. until about a quart of oil came out of the breather hose and there was almost no oil in the tank. Replaced the umbrella valves with new blocks as well as opening up the drain hole under the umbrella valves. Drain oil out of motor block too. Got it all back together with new o rings in the oil pump. fire up and run with cooling fan on motor and within a few min the oil started running out over flow again.
OK what I did next was just desperation but I removed the oil return line and attached a long hose and ran it back into the fill lid on the oil tank . started motor and it ran with almost no oil out breather lines. Put on new return oil line and made sure it did not have any blockage, top oil back up and fired it up but this time I left the lid off the oil tank and it ran with almost no oil out breather. Put lid back on and within a few min the oil started pouring out the breather line..
Now I am thinking the return side of the oil pump may be too weak to handle the oil. PS They used stock oil pump and cam plate on the build.

 

You might want to pull the A/C assembly off and see if the stock A/C breather bolts are in or if it has solid bolts in place of the stock (vented) bolts. Just a thought, inspired by a self sabotage that I was guilty of a few years ago.

Wish you the best in this one. Sounds complicated.

 

My suggestion would be to clean or replace the A/C filter. A clogged filter will suck the oil right out of the heads.

 

Not sure what your problem is but two things you did, did not help. My guess is you have a oil pump problem. Either a worn out or broken one or a missing o-ring since you are talking big time oil and not just a few drips. The two things you did served no purpose. The umbrella poppet valves are one way out valves. They truly do not stop the oil. The other is by enlarging the drain holes allows crankcase pressure to blast straight up thru the bottom instead of thru the baffle area. So that makes it worst since the original holes are sized correctly. Not to small but mostly importantly not too large. If you have a lot of blow by, it can overwhelm the vent also. However, you would thing that would show up as a weak ill running engine. Also, the bores for the lifters are important to be correct to lifter. If the fit is worn, the oil running in will not get up to the top. Obvious not your problem. A lot of cam overlap will generate a vacuum followed by pressure wave in the crankcase that generates more blow by in the vent but talking a few drops. Not like you describe however. Also remember, a TC should only have 8-12 lb idle oil pressure since the oil injectors have a 21-18 pressure requirement to work to prevent overwhelming the cylinders. The 35 lb pressure relief should also work in the standard cam plate and a Softail require the one with the screen filtered oil to the balance chain tensioners. Someone on here had a piece of rtv trash blocking the drain passage in the head beside the valve spring.

 

Pull the rocker covers, start the engine, and ensure that:

1) oil returns are not blocked.
2) you are not getting 1 gallon of oil per minute flowing out the rocker arms (fire hose).
It should be literally drops of oil coming out per side, per head.
If you get way too much flow (like filling the head in seconds - which is why it would be coming out of your breather tubes at a huge rate), your oil pump pressure spring is wacked or something else in the oil path is jacked, including the return vaccum through your pump back to oil pan.

Short version anyway.

 

Leaving the oil cap off no problem, install and oil flows out. equals clogged oil tank vent in my opinion.

 

Didn't know of vent for oil pan, thought it vents threw breather's

 

Actually this thread is in wrong place since we are discussing a Softail Fatboy. They have the oil pan (bag) above the engine in a horseshoe shaped tank. It's under the seat and also serves as a battery box inside the horseshoe shape. There are three hoses coming to it plus the drain hose for it out the bottom that connects to a frame crossover bar with the MS o-ring seal drain.

The other hose out the bottom is to the suction side to the oil pump thinner gerotor pressure side that feeds oil to engine. A upper return line from the larger side of the oil pump thicker gerotor. And the upper vent line to the engine that uses the engine vent to the air filter body.

In the last section of the oil feed explanation in the service manual. It says this return line enter behind the rear lifter cover and connects the cam compartment with the oil tank via a third drilling in the transmission case. This crankcase breather connection provides the pressure balance necessary for oil circulation.

To the best of my knowledge, this is unique to the Softail transmission. I have see others that actually dispute this and say that is not what it means. I know I have looked at two Softail transmission and have yet see this passage way in the transmission.
The Softail transmission does use the rubber hose vent to vent the primary thru the clutch push-rod cavity.

 

I had a similar problem with my 12 Road Glide. Summer of 14 I put 7 air filters in it. Started about 30000 miles took it to two dealers one in Wi the other close to home and
both replaced the umbrella valves,air cleaner, upgraded oil pump to SE once and probobly
a few other things that I don't remember. Ended up the fall of 14 they took it in and did a
leakdown test and it was within spec. but they ended up replacing pistons,rings and jugs and it quit doing it spent most of the summer replacing air filters

 

got everything fixed back together and running great. The problem was the oil pump failed (return)and let the lifters run without oil causing scrapping and shavings in lifter holes to clog up in the cam support plate, further restricting oil return to tank thus pushing it out the breather sys. new cam support plate and new lifters. solved the motor problems .. Then found a skinned wire under a piece of chrome going to the tach causing momentary miss fire.