Help, engine timing

[redka]

My son hit a stump( where we cut down a small 3" sapling last year) with the deck of his Troybilt 42" mower. The engine immediately began sputtering and did not have enough power to cut. When he disengaged the blades the engine ran. When he re-engaged the blades the sputtering came back. What could be the problem, and is this something we can fix? Help much appreciated.

[ToadHill]

I'd start by looking under the deck and see if a blade is bent and digging into the ground or have they jammed somehow. It sounds like the load on the engine is causing it to sputter and if disengaging the blades stops the problem, the only problem I can think of is with the blades.

[dqdave1]

Remove mower and inspect. All blades should turn freely. Look for bent blades or a bent shaft. Make sure belt is in pulleys properly. Belts may have jumped off a pulley.

[elad]

IF the other suggestions fail; you might want check if the key
on the crankshaft may have split just enough to change the timing.
The key holds the crankshaft and fly wheel in time for when to
fire the plug. If a little sheared, could run as you describe.
Full shear---no run at all. Just a possibilty. good luck elad

[redka]

I checked and the blades turn freely and not bent. It took a hard lick as the end of one blade is nicked and the deck dented in. Contrary to what I posted, the motor does not run smooth when blades are disengaged, so maybe the key is sheared, or partially so. Will have to get someone to take a closer look. Thanks much for the help.

[dqdave1]

If it is running rough; the flywheel key is no doubt bad. Not that hard of a job to fix. Remove flywheel shroud and accesarry items. Loosen nut on flywheel; use puller to remove flywheel ( sometimes putting nut onback on shaft till flush and rapping shaft with a hammer using a piece of wood to protect the shaft will loosen the flywheel). Replace key and reassemble.

[redka]

dgdave1, I'm thinking about giving it a try if I can locate a flywheel puller. Is the nut a right or left hand thread?
Also, I'm not quite understanding what you are saying in the parenthesis.
Thanks.

[dqdave1]

Standard thread; righty tighty. If you do not have a puller; loosen the nut but do not remove; Place a piece of wood on top of nut ( put nut flush with top of bolt) Rap the wood with a hammer; the flywheel will come loose. The shaft the flywheel is attached to is a tapered shaft. Striking the shaft can loosen the flywheel. Just do not go crazy with the hammer. Puller is nice.

[redka]

Got it. Thanks.

[redka]

dave, I got the flywheel nut off and looked into the hole...the shaft, key, and flywheel were all lined up, so I didn't bother to try to remove the flywheel.
The blade that got jammed against the deck does not spin freely. It turns OK by hand, but doesn't actually spin loosely. Could that spindle be slightly damaged and that small bit of bind be causing the engine problem?
I have heard mention of a counterbalance. Is this INSIDE the engine, what is it, and could that be the problem? Again, when engine is running with blades disengaged it does not run smooth, but when the blades are engaged, engine sputters and pops really bad. Thanks for anyone's help.