Busted my engine

[widefat]

What do you think the problem could be?
I was mowing a rough area with my pushmower when I hit something;
I heard the blade hit it, and a split second later a
VERY loud whack as the debris hit something inside the deck.
I hit stuff constantly where I use this particular mower; this
time is was magnitudes louder.
Immediately, the mower started struggling to run - as if it were being
fuel starved.
I am afraid it hit just right and cracked the block.
No oil seepage or smoke - the mower just struggles to run.

Thoughts?

 

[SSdoxie]

More than likely you partially sheared the key in the flywheel. Simple fix, remove flywheel and install new woodruff key.

 

[TCJatko]

Many vertical shaft mowers have a large-ish flywheel on the top containing a metal slug that initiates the spark as it rotates by a stator. When you hit an obstruction, sometimes the crank will stop rotating and the rotor on top will keep on moving. The engine then becomes out of time, hence the rough running or struggling. Take the top housing off and replace the Woodruff key on the rotor. This should cure the problem.

Oops, SS beat me to it.

 

[widefat]

Sounds good....I'll pull the flywheel and check the key.

 

[Gunny]

Sounds good....I'll pull the flywheel and check the key.

If it's a Briggs, when you check the flywheel key, if you see even any marks on it, replace it. I had problems once and pulled that darned flywheel several times working the issue. The key looked good, just a very slight mark, it didn't look like it could affect anything, but once I finally replaced it, the engine ran.

 

[widefat]

If it's a Briggs, when you check the flywheel key, if you see even any marks on it, replace it. I had problems once and pulled that darned flywheel several times working the issue. The key looked good, just a very slight mark, it didn't look like it could affect anything, but once I finally replaced it, the engine ran.

Fortunately, I did just that - I pulled the flywheel and the key was intact. At that point, I was sure something else was wrong. But, I had a new one, so I replaced it anyway, thinking what the heck..
Got it back together, and it runs fine now. Go figure -

 

[CCWKen]

Back in my old days of Kart racing, we used an off-set key to advance the timing. The off-set was something like .010" or less and made a huge difference along with a radical cam. A few other mods gave a Briggs 5hp the ability to run 5,000+rpm all day on methanol. Fun times back then.

When the blade stops and the flywheel keeps going for even a .001", it slips into a ****** state. That makes for a poor running engine.

Glad you got it going. Mow-on!