On Thu, 12 Jul 2007 14:01:30 -0000, wrote:

I've got a 13 year old MTD riding lawn mower. It has a 12hp Briggs
and Stratton engine. It ran fine one day and the next day it blew
fire out of the muffler, (I didn't witness that with my own eyes)

Who was running it when the problem occured? Did they hear
a "Clunk"??

it
has oil in the muffler and the last time I tried to start it, it
spewed a lot of oil out of the air intake.
Do you have any ideas as to what could cause this?
I was suspecting the rings and I've taken the cylinder out.

You removed the cylinder? Or just the head?

What am I
looking for at this point?

I'd look for a burned/mutant valve, among other things.

Upon visual inspection, I'm not seeing
anything that catches my eye. Is a visual inspection enough to
determine if the rings are bad?

You should be able to tell if a ring is cracked, if the
cylinder is off.

I was expecting to find something obvious since it went from working
fine one day to broke the next. Maybe it's not the rings. Any other
ideas or suggestions?

Look at everything that you can see. Are the valves warped? Is
the cylinder scored/damaged? Is the block intact? Does the piston
move properly and the valves open/close properly when you turn it
over by hand?

Time to take a full inventory of functional motor components.

Puddin'

"Mit der Dummheit kaempfen Goetter selbst vergebens!"
-Friedrich Schiller