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Posted by dale.prather on July 12, 2007, 10:01 am
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) 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. What am I
looking for at this point? Upon visual inspection, I'm not seeing
anything that catches my eye. Is a visual inspection enough to
determine if the rings are bad?
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?
Thanks for the help.
Dale
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Posted by Puddin' Man on July 12, 2007, 12:00 pm
On Thu, 12 Jul 2007 14:01:30 -0000, dale.prather@gmail.com wrote:
show/hide quoted text
>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"??
show/hide quoted text
>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?
show/hide quoted text
>What am I
>looking for at this point?
I'd look for a burned/mutant valve, among other things.
show/hide quoted text
>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.
show/hide quoted text
>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
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Posted by dale.prather on July 12, 2007, 12:32 pm
I removed the piston from the cylinder. None of the rings are
cracked.
The cylinder doesn't have any scores or doesn't appear to be warped.
The valves open and close properly. When I manually pushed open the
intake valve oil drained out of it. Could oil somehow be getting into
this valve instead of leaking around the piston/rings? Can you think
of anyway that's possible? I'll investigate that tonight.
When I drained the oil, it was a nice mixture of oil and gas.
Looking for more ideas. If I find anymore clues tonight, I'll post
it.
Thanks,
Dale
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Posted by Puddin' Man on July 12, 2007, 2:39 pm
On Thu, 12 Jul 2007 16:32:06 -0000, dale.prather@gmail.com wrote:
show/hide quoted text
>I removed the piston from the cylinder. None of the rings are
>cracked.
>The cylinder doesn't have any scores or doesn't appear to be warped.
>The valves open and close properly. When I manually pushed open the
>intake valve oil drained out of it. Could oil somehow be getting into
>this valve instead of leaking around the piston/rings?
Yes. A valve problem was my first guess.
show/hide quoted text
>Can you think
>of anyway that's possible?
Warped valve stem, maybe damage to the valve guide.
show/hide quoted text
>I'll investigate that tonight.
>When I drained the oil, it was a nice mixture of oil and gas.
Ouch!, Ouch!, Ouch!, and Ouch! Are you sure?
show/hide quoted text
>Looking for more ideas. If I find anymore clues tonight, I'll post
>it.
I likely shouda mentioned I'm not familiar with your machine,
just know a little about 4-stroke motors.
Is your B&S motor a "flathead" or is it OHV?
P
"Mit der Dummheit kaempfen Goetter selbst vergebens!"
-Friedrich Schiller
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Posted by Oren on July 12, 2007, 5:17 pm
On Thu, 12 Jul 2007 16:32:06 -0000, dale.prather@gmail.com wrote:
show/hide quoted text
>I removed the piston from the cylinder. None of the rings are
>cracked.
>The cylinder doesn't have any scores or doesn't appear to be warped.
(A compression check first .. before a piston is pulled)
This would be an excellent time to hone the cylinder and put new rings
in.
show/hide quoted text
>The valves open and close properly. When I manually pushed open the
>intake valve oil drained out of it. Could oil somehow be getting into
>this valve instead of leaking around the piston/rings? Can you think
>of anyway that's possible? I'll investigate that tonight.
Valves can "appear" to work properly. A weak spring can affect the
working of the valve, so it may not completely seal.
show/hide quoted text
>When I drained the oil, it was a nice mixture of oil and gas.
>Looking for more ideas. If I find anymore clues tonight, I'll post
>it.
>Thanks,
>Dale
Oren
..through the use of electrical or duct tape, achieve the configuration in the
photo..
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>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)