Small Engines (Lawn Mowers, etc.): Second engine oil seal change, briggs stratton, belt tension

Question
I have a Briggs & Stratton, 20 hp, INTEK V-Twin mower engine. Model # 406777, type 0128 E1.  This engine is 7 years old with 150 hours on it.  The problem is that I have replaced two (2) engine oil seals (PTO Side/Bottom) in the past 10 hours of use.  The color of the oil worries me thinking that something internal might be making the shaft wobble.  The oil color is dark gray looking.  What could be wrong?  Does this mean a rebuild this winter?  Any help would be appreciated.  Thanks    Barry

Answer
You have a lower main that has/is failing.  The grey in the oil is aluminum.

The usual cause of a lower main failure is either excessive belt tension or a bad ground on an electric PTO clutch, usually the latter.

If an electric PTO clutch has a poor ground the clutch will try to ground through the crank. The crank isn't actually touching any metal. It is traveling on a thin film of oil.  This causes the clutch, in a search for a ground, to blow microscopic arcs through the oil  to the crankcase.  This leads to pitting on the bearing surface, eventually eating the bearing away.  A rebuild won't help unless you replace the sump/oil pan.  Don't wait until winter to do the sump replacement, every minute it is ran in this condition is one minute closer to crankshaft failure.