Cracked Flywheel Collar

[ILENGINE]

Steel key will do it. I still think that even with the steel key it wouldn't break until it either hit something or was not properly tightened down.

 

[yama0918]

I understand that a steal key will not shear if the blades hit something. However, on my good engine, all I did was remove the flywheel and then reinstall it using the wrong key. I did not drive it or engage the blades. All I did was start it and a few seconds later the collar broke. The key was not protruding above the collar. The top bolt does not have a washer and was not over tightened.

 

[reynoldston]

I understand that a steal key will not shear if the blades hit something. However, on my good engine, all I did was remove the flywheel and then reinstall it using the wrong key. I did not drive it or engage the blades. All I did was start it and a few seconds later the collar broke. The key was not protruding above the collar. The top bolt does not have a washer and was not over tightened.

Your money and mower do what you want. With a steel key you will not only damage the flywheel you will also damage the crankshaft. The best lesson would be do it and find out for yourself what I am talking about. B&S designed that key for a reason. With the right B&S key you should tighten the flywheel down real well.

 

[yama0918]

I bought two used flywheels and got the correct B&S keys. After reading additional forums, I realized what the problem was. The main problem was that I did not tighten the flywheel bolt enough which would cause the flywheel to slip. If I had the B&S key, it would have just sheared. Because I used a steel key, it cracked the flywheel. I was mistakenly under the impression that it was the key that keep the flywheel in alignment with the shaft. But it is the torque of the bolt that pulls the flywheel against the tapered shaft that holds the flywheel in place.

After installing the replacement flywheel and key on one mower, I torqued the bolt to 55 foot pounds. The mower started right up and ran correctly. I then did the same to the mower with the engine I just rebuilt and that one started and ran also. I stopped and started that engine twice and on the third time the engine would not start. The engine was locked up.

I removed the engine and started taking it apart. I removed some parts so that all I had left was the crankshaft and piston and it was still locked. I removed the bolts from the bottom of the rod and now the crank would rotate and the piston would move. The cylinder sleeve is smooth as can be. So it appears that something was just binding. I reassembled the engine but when I start to tighten the bottom case, I cannot turn the flywheel anymore.

Any ideas???

 

[reynoldston]

Are you checking the oil clearances on your rod and main bearings? It should have at the lease .003+