Small Engines (Lawn Mowers, etc.): Oil leaking from exhaust, shaft seal, white smoke

Question
I have a B&S 300 Series 148cc 4.50 (a cheap Walmart buy). The first time run the blade shaft seal twisted and started leaking oil. Having warranty I put it in the shop, five weeks later I picked up the mower. I've had the mower back for about a month and have only mowed twice. Upon trying to start it for a 3rd mow, white smoke came out of the exhaust. I've seen this before on other mowers and was not alarmed. However, the mower refused to run. Oil is leaking from the exhaust. On further inspection, oil had covered the bottom of the air filter and the spark plug is cover in it (very black). I checked the oil, which in my opinion has the hint of a fuel smell, it looks a bit watery and a greenish gray color (not the color that went in for sure!) If I continually prime it (while someone else starts it) it will somewhat stay running, but as soon as I stop priming it dies. Is this something I can fix, or does it need to go in the shop again (which by the time I get it back summer will be nearly over.) If I am able to fix it myself, could you please tell me the steps?

Thanks in advance for your help,
Laura

Answer
The symptom you described is ver common with a leaky carburetor inlet needle seat.  You can replace the inlet needle yourself but if the mower is still new I would try to get warranty on the mower.

You will also have to change the oil.

How old is the mower?  Will Wal-Mart exchange it for a different one?  I've only had one other mower that twisted the lower seal out.  Replaced seal, it did it again and the engine threw a rod because it was out of oil.  This engine was most likely defective as the seal came out in less than a few hours of operation.  Briggs replaced the engine under warranty.

If the seal came out in less than 10 hours of operation I would seriously question it a a possible factory defect.

Eric