I'm working on this as I write this post.
Thought it would be an easy fix.
Looking at the pics you will see a pool of oil on the mower deck. I cannot for the life of me determine where it's coming from. No place does it appear to be leaking or does one spot seem to be the source.












I thought perhaps the oil fill tube but again there is no more or less oil indicated in this or any other area. I cleaned the whole engine off and still do not see any area that is not tight or leaking where gasket might be. The gas is clean as is the oil with no contamination from either source.

If I clean it and add a little bit of oil to meet the proper level it will run just fine. Let it sit about a week and the pool appears again. Sometimes the amount of pooled oil is less, sometimes more. Occasionally between cuts (about once a week) there will be no leakage.

One last note. The oil fill tube does not have an "O" ring as it sit on the engine block. Should it? But I can't see where enough pressure would be applied by the screw holding the fill tube could make a seal.

Any thoughts?

 

The oil fill tube should have a rubber gasket to keep it from leaking. Also, the oil level should not be high enough for it to overflow out of that hole. When the engine is running, it will leak without the gasket.

 

Does not leak while running. Yes the fill tube has a gasket type sleeve that it inserts into. All the cowling, gas tank and starter pull is off. I cleaned the outside of all grime and dirt. I'm going fill it with oil without the fill tube attached (that way I'll be sure not to over fill it) and let it set for a day, few days or week and see if I can pin point area of leak.

 

additional info: The book says it takes 20 OZ of oil. I added 16 OZ with out the oil fill tube attached and can't add any more. Inserted the dipstick tube and it says to add oil. If I add more it will rise up into the fill tube. And yes I did pull the plug and turned the engine by hand. Good compression and it wants to push oil out the fill hole. Go figure.

 

Crankcase breather tube loose or cracked?

 

It seems that I have to tighten the Breather Assemblies once a year on every B&S Engine I own; otherwise they begin to leak, and damage their gaskets.

I've also found that Head Gaskets need to be re-torqued after a couple years of usage. Once they loosen to the point that the Head Gasket leaks, it's too late.

 

Breather tube? I'll check it. No signs if any gasket area as being oily or leaking. They all seam dry. Head gasket is dry all around the cylinder head. And the mower runs very well. No signs of poor compression or leaking when its running. Right now it's filled oil and just standing there. Remember it only seems to have a problem when it sits several days or a week.

 

Those engines are terrible for leaking at the gasket that holds the top and bottom together, the bolts get a little loose and crankcase pressure blows out the gasket. I think the crankcase vent gets clogged. Also in your pics the oil filler tube doesn't look like it is seated properly. Have a good one. Geo