Yesterday while I was mowing the lawn, my mower engine suddenly
stopped. The blade continued to spin until it slowed to a stop. It did
not strike any objects. It was working fine up to this point.
When I attempt to start the mower by pulling the string, the blade will
spin quietly, but I do not hear the engine try to engage. Additionally,
it feels "loose" when I pull the string; previously, I could hear the
engine cranking, but not anymore.
I'm not very experienced with lawn mower or small engine repair, but I
did some basic troubleshooting by looking at guides on the web. The
flywheel key, and the blade adaptor key both seem to be intact. The gas
is fresh. Oil was recently filled.
My mower is a Craftsman, model 143.996504 with a 6.5 Eager-1 (Tecumseh)
4-cycle engine (917.377431).
remove plug, ground ignition wire well to engine block away from plug
put finger gently over plug, pull or get someone to pull cord.
do you feel compression? in and out feeling
sounds like broken valve etc from your description easy to pull.......
Engines basically don't run for one of two reasons:
If you pull off the spark plug wire, and hold it near the engine (mayb
1/4"), do you get a spark while cranking the engine?
Remove the spark plug (special wrench/socket needed), is the gap either
excessive ( > 0.030"), or bridged with carbon fouling? If either,
clean, reset gap, and put the plug back in.
If you are getting fuel, you should be able to smell it. The plug
should be wet, if there is no spark.
How about the air filter? If it is the sponge type, it needs to be
washed out now and then. If it is the paper kind, they have to be
replaced every season or so. Take a good look at it. In a pinch, use a
whisk broom to clean off the grass clippings, crud, on the surface of
the air filter. Put it back in.
That should give you a good start. Also, the manual that comes with
your mower should give basic maintainence tasks that you can do.
When you turn the engine over with the pull cord, you should feel some
compression, unless the engine is very worn.
If you pull the cord but don't feel and/or hear the resistance of
compression, it is probably trash. You've lost a valve or ring.
I would guess that you would not be comfortable taking the motor
apart to see what may be holding a valve open.
Feeling for compression at the spark plug hole with the spark plug
out is more scientific.
My personal decisions about small engines:
No compression - trash can
Bent crank - trash can
Otherwise they are usually fixable.
If you have compression, it is probably the flywheel key. You
cannot tell unless you remove the flywheel which requires removing
the pull rope mechanism, the shroud, and probably the fuel tank.
This give you the opportunity to reset the magneto, slip in a new
flywheel key (under $5), and clean out the old dead grass and
crud. It would be a great time to give it a fresh pull rope too,
before the existing one breaks.
Keep the whole world singing . . . .
DanG (remove the sevens)
I will go with the lost compression. If you are up to it you could pull
off the head and see if a valve is broke. I do remember one one rare
occasion a valve stuck open. Just took some lubricant to get it moving
Pull the spark plug wire off, and secure it well away from the spark
Leave the plug in.
Tip the mower on its side, and try to turn the blade backwards of the
If it spins freely, scrap the mower, and get another one. If it binds
and gets hard to turn at one or two places in the revolution, then you
have compression. Proceed to look for other problems.
Christopher A. Young
You can\'t shout down a troll.
On Sat, 19 Aug 2006 21:57:12 GMT, "Stormin Mormon"
I thought with the plug in, the blade could kick back when released or
when it slipped out of one's hand. Not enough to cut off a finger,
but enough to hurt, no?
And the engine won't start because the spark plug wire is off and
"secured" "well away", if it really is. The first time, it probably
will be. The second or third time, one might forget. And I used to
hook the wire to the fuel line, which in an old mower was a convenient
place, but sometimes it sprang loose and went back to within a quarter
inch of the plug, close enough for the engine to run.
And anyone who is pushing the blade backwards might want to push it
forwards too, not realizing it would be more likely to start.
One could use a stick to push the blade backwards. God only gave us
The other posters have some good advice, but from your description it sounds
possible to me that your engine has a connecting rod broken at the
crankshaft end. That is based on engine spinning freely without any sounds.
The engine is likely beyond economical repair.
There are some other possibilities, such as a valve being stuck open, that
are easily repaired. If it spins over easily there can be no compression. I
would have someone knowledgeable have a look at it if possible.
Nothing like the sound a "knocking rod", spun rod bearing, or broke
Easily checked at the tappet filter / crank breather (if this model
has one) - remove it and pull the cord...the valves should move and
easily viewed. The easy way; pull the plug wire and plug, determine
which digit goes into the plug hole. Rotated through all four
strokes: intake, compression, power, exhaust - you can feel the intake
pulling the finger, Compression stroke will blow the finger out.
I think I had one once, where the pin holding the spring in place had
come out. One spring of the two was fully extended, even more than
needed to close the valve. The spring was iirc loose, because nothing
held it in place at one end. At the time, I would never spend enough
for a valve spring tool, but a shop could have fixed it in a few
minutes I guess.
The easy way; pull the plug wire and plug, determine
replying to digitkgb, derrick wrote:
i have a "weedeater one" riding lawnmower. It is a small one. My brakes are
bad. The brake pedal just goes straight to the floor without any resistance.
What could be the problem?
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