Small Engines (Lawn Mowers, etc.): Oil Leak on a Tecumseh Engine, bolt holes, head gasket

Question
Hi Michael. I appreciate any help you can give me. I have a 1983 Troy-Built Rototiller with a 6HP Tecumseh engine on it. The model number is HH60 1C5115H. The serial number is 3054D. I lent the tiller out to a relative, and you guessed it, it came back broke.  I gave it to a friend of the family to get it fixed. He said it had a cracked head and a bent valve.  It looks like he put a used head on it, but it seemed to run good.  Only problem now is, there is oil leaking out of one of the head bolts and it also looks like maybe some oil leaking out of the breather.  I'm disabled (a lot of back operations), but I was so frustrated when I saw this, that I took the head off and cleaned everthing up to try to find out how this oil could be leaking out of a head bolt. Could it be that I need a new head gasket?
I thank you for any help you can give me.
Doug  

Answer
Hi Doug,

It is hard to say what could have been done during the repair.  If a valve was bent, the valve guide may be damaged and leaking there or over pressurizing the crankcase.  There should not be oil in the tapped head bolt holes unless one was drilled out deeper.  Oil may be leaking through the valve guide and into the head which may then leak through a bad head gasket.  In that case, the engine would smoke.  You could try a new head gasket.
You may have a mess on your hands.  Sorry I can't be more specific.  Maybe you could find out what happened to the engine that caused the initial damage and exactly what was done during the repair.

Keep me posted.
Michael