Thought crankshaft was bent doesn't look physically bent. HELP

[philluzader]

Kohler brand sv540 engine in a 2008 Troy bilt bronco. 13av60kg. Last year hit something and mower developed shake. Forgot about it until now had to use some starter fluid to start mower and the shake came back to me. It shakes without blades engaged. Took engine apart and crankshaft looks ok to me. Could it be a tiny bend or something else? Any help would be greatly appreciated.

 

[ILENGINE]

Rider crankshafts seldom get bent because the drive belt absorbs the shock load. I suspect something else is messed up. Remove the engine pulleys and clutch and then start without anything on the shaft and see if you still have a shake. If still shaking then I would worry about tearing into the engine and founding out why.

Looks like you are into the engine already so wouldn't hurt to check the counterbalance weight and see if it moves side to side like the linkage has broken because that was an issue on some of those bucket style engines.

 

[philluzader]

I did get into the engine already. Turns out it's a good thing I did found some pieces I believe came from the governor pulley assembly in
the crankcase chilling. Everything looks in order on the governor pulley though. I'm guessing it was serviced before I bought it and they didn't find those few pieces. I'll have to rebuild and wait for a new crankcase seal to come in and try and start it without engine pulley attached and see what happens. Also some damage on counterbalance but I don't think enough to cause the shake.

Once I get it together I'll let you know.

 

[shadeytree]

Those pieces you found might be counter weights that provided engine balance. If the crank shaft is light opposite the piston, metal weight might be welded on. If the crank shaft is heavy opposite the piston, holes might be drilled in the shaft to remove metal. If you can determine that those pieces were welded on, perhaps you can re-attach them onto the original positions.

If the crank shaft is bent, it is more than likely bent outside the motor.

When the engine is back together but before you install it on the mower clamp something stationary to it. A tool or piece of metal or wood that is near but not touching the shaft where the shaft extends from the motor, but as far away from the motor housing as possible, can tell you if it is bent. When the engine is turned the distance between the shaft and the clamped on piece should remain exactly the same. If there is any change in the distance you know the shaft is bent. A bent shaft can be straightened.

This is video is not showing a motor with a pully, but the principle is the same.
I've straightened a few shafts using this redneck method ;-)

 

[bertsmobile1]

I did get into the engine already. Turns out it's a good thing I did found some pieces I believe came from the governor pulley assembly in
the crankcase chilling. Everything looks in order on the governor pulley though. I'm guessing it was serviced before I bought it and they didn't find those few pieces. I'll have to rebuild and wait for a new crankcase seal to come in and try and start it without engine pulley attached and see what happens. Also some damage on counterbalance but I don't think enough to cause the shake.

Once I get it together I'll let you know.

Check the decompressor they shed little bits of shrapnel as well.