Why does the air filter housing fill with oil?

Compression 140 and 150 PSI

Single bore carburetor (extremely high vacuum)

Oil breather new, plenty of crank vacuum (will suck all the water in)

Plenty of pressure on the filter side? The old original breather the same






Might add, it is worse in hot condition (Spain) Oil dripping on the starter

Forgot to add.

Inside paint is peeling off.

hard to see whats going on in your photo as i need to see both ends of the manomiter

from the 2nd picture if that is LHM moving toward the open end then the breather isn't working as the crankcase is going positive - and by quite a bit.*

it should be sucking the LHM into the engine

remember to test it at high revs where even the best original style breathers drop to barely any depression.

* edit
it looks like you have connected the manomiter to the outlet of the breather - the normal way is to remove the dip stick and connect on there where you measure whats going on in the crankcase

Sean too much Whisky

It is colored water.

Yes tube in to the dipstick
Yes tube in to the hose between breather and filter housing (to measure pressure)

One end in DIPSTICK
Other end OPEN
Measures VACUMN (small)

I try
As Pete says one end in the dip stick the other open to atmosphere you are just measuring either side of the valve and creating a closed loop you need to test the difference between crankcase and atmosphere.

Use LHM because if it gets sucked in to the sump it's no big deal....save the water for your whisky

Boys no more whisky to you. I do know how to test an oil breather. Yes one end is open, the other in to the dip stick. Very good vacuum

Same measuring the pressure in the hose between breather and air filter housing. Massive pressure but why is the air filter housing filling with oil when vacuum is very good (also at high revs)?

PS. water sucked in will just evaporate while driving. no worries

BTW. Thanks for the beer in Spain, it fell on a dry spot

Interesting. Why doesn't it evaporate out of my engine? It forms an emulsion inside the filler cap and rocker covers?

Is that paint from inside the breather/filler?

Damaged oil controller rings in fact worn rings won't necessarily show up on a comp test if there is enough oil to seal up the damaged bores/rings

Oil in the air box points to damaged rings (140 is on the low side especially if the other side is showing 150)

What's the vaccume at high revs pipe in dipstick everything else connected.
Advanced timing can cause a healthy engine to blow oil.