Small Engines (Lawn Mowers, etc.): Fuel in Crankcase, vanguard ohv, engine crankcase

Question
I have a Sabre 1646HS with the B&S Vanguard OHV engine model 280777. Have had no problems, used it twice this season. Yesterday, it would turn over, but slowly, but wouldn't fire, as if no spark. With jumper cables, would turn over, but no start. Pulled the plug and it was fuel soaked. Tested fine with good spark outside engine. Reinstalled plug, nothing, but finally reluctantly started at low throttle. After about a minute, it stopped. Next start attempt gave lots of white smoke. After looking at this web site, I checked oil and had lots of fuel in the crankcase. I must have something stuck in the carb. I drained oil (at least twice as much fluid!)removed filter and noticed slight mettalic flakes in oil. Removed air filter, also oil and gas soaked. And saw again this mettalic residue. It looks copper colored,(like antiseize compound).
So I'm off to buy the filters, plug, carb rebuild kit.
1. How did the fuel get in? did it back up to the air intake, then down the breather tube? (Is this the equivalent of the PCV valve on a car?) But doesn't that breather also have a one way valve? (I can guess the fuel just leaked past it?)
2. Because of the large volume of fuel in the case, did I just stir up some deposit of residue, giving me that metallic copper color residue? The particles are extremely fine. Is there a bearing I fried?
Since this engine is over 12 years old, and got the tractor for $300 3 years ago, it owes me nothing. Should I put in the new parts, rebuild carb, and see what happens? (With lots of caution on the first few runs, maybe 15 to 30 sec max.

Thanks in advance!!!
Dave in NYS

Answer
Fuel can leak past the carb inlet needle and enter the engine crankcase through the valves or valve breather.  A good fuel system cleaning, including the fuel tank and fuel lines plus a carb cleaning and replacing the inlet needle valve usually solves the problem.  Use compressed air from an air compressor to blow the tank and fuel lines clean as well as cleaning all the carburetor orfices (holes)

Drain and refill the oil.  You can run the engine for about 5-10 minutes to warm the new oil and change again if you want...new old does not cost much and I do not run synthetic in my mowers.  I run the cheap oil but change it often to help clean out the engine.

I doubt any bearings are fried, usually there is no real bearing per se, but rather a bushing.  I'd just change the oil and run it.

If you want to make certain the problem never happens again you can install an inline fuel shut-off valve and turn the fuel off when you are done mower.  I use fuel shut-off valves on my personal mowers.

Change the oil, clean the carb, replace the inlet needle and I'm betting you can use the engine another 3 years.

Eric