Small Engines (Lawn Mowers, etc.): Sears Lawn Tractor, briggs and stratton, dipstick tube

Question
While mowing the lawn yesterday the engine backfired and blue smoke emerged from the exhaust. I opened the hood and the plastic cover on the flywheel had blown off taking the dipstick tube with it. After reattaching the dipstick tube I started the engine which ran smoothly with the exception of the continuous blue exhaust. What's the likely problem? What's the likely fix? Will it damage the engine to continue to run the machine? The engine is a Briggs and Stratton 15.5 HP OHV model 28N707.
Thanks for the advice

Answer
Hi Randolph,

Check the oil level to see if the engine is using oil.  It must be, if it's smoking.  You may have a bad exhaust valve.  Do compression test to confirm this.  As long as you maintain the oil level, you should be able to run the engine with no harm to it. until you solve the problem.

Let me know what you find.
Michael