Kohler Courage XT-6 burning oil

My Craftsman push mower suddenly started burning oil after running about 20 minutes. It wouldn't restart after I turned it off.
Oil was coming into the carb from the breather hose. I put an old (dry) plug in it and installed last years air cleaner (I'm slow to throw stuff away).
It started, smoked a little more, then settled down and ran fine for an hour.
I found the service manual online for the engine. It says there should be 4" minimum of vacuum in the crankcase while running.
I jury rigged my vacuum gauge to the dip stick tube and measured ½" of vacuum.
Google searching I found a youtube of a guy demonstrating how to measure the crankcase vacuum.
His jury rig was a little different than mine, but his engine vacuum was ½", the same as mine. He said this was good??

Anybody tried to measure the crankcase vacuum or have any thoughts on this?

OK I can suck and blow through the breather. Not good. A little more resistance blowing than sucking.
With my little hand operated vacuum pump, if I pull a 5" crankcase vacuum through the breather, it will bleed-off at about an inch every two seconds.

Getting to the breather on this engine looks like a PIA. I'll put that off until another day.

Small engine use inches of water not inches of mercury. So If you use a standard vacuum gauge it is most likely for mercury not water.

Have you checked your oil level? Has the oil been diluted with fuel, does it smell like gas? Have not seen any faulty breathers on these engines.

ILENGINE said:

Small engine use inches of water not inches of mercury. So If you use a standard vacuum gauge it is most likely for mercury not water.

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Thanks for your reply.
You are correct. My vacuum gauge is inches of mercury. I reread the service manual and it does indeed say inches of water. That did not register the first time I read it.
Google tells me ½" of mercury equals between 6 and 7 inches of water. Looks like I am in good shape there.

Ran it for two hours today with no problems. Mowing season is about over here, so I'll wait and see how it behaves next year.
Thanks again for your help.

Rivets said:

Have you checked your oil level? Has the oil been diluted with fuel, does it smell like gas? Have not seen any faulty breathers on these engines.

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Thanks for your reply.
The oil level is correct and no fuel contamination.