Ask the Mechanic

Worn Teeth

(Progressive Farmer image by Steve Thompson)

READER: I have a Farmall C that has an occasional starting problem. The teeth are worn off a spot on the ring that goes around the flywheel. I think I will need to replace this ring that the starter engages to start the tractor. It makes a grinding noise when it does not spin over the engine. I can grab the fan and move the engine a little, and she will start just fine. How do I go about changing out this big ring?

STEVE: You have located your problem. The good news is that you are only going to spend a few dollars for the part. The bad news is that you will need to split the tractor between the engine and the bell housing. The starter ring fits on the flywheel by a process called thermal expansion of the starter ring. You can heat the old starter ring with a torch by moving the heat around and around the ring until it falls off. You can also use a torch to slice it and knock it off with a hammer and punch.

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What I like to do when possible to make the installation easier is to put the flywheel in the freezer for a few hours. This contracts the flywheel circumference. Then, quickly lay the new starter ring on the flywheel and begin a circular motion around the ring. It will expand and eventually fall over the flywheel -- magic. However, do not leave the torch in one place very long, and never let any part of it get red hot. If it gets red hot, it will become annealed, which means it transforms into a softer state.

For some reason, an engine likes to stop near the exact same location. That is why a starter ring seldom shows any wear except in the "bad spot." By the way, when changing the starter ring, this is an excellent time to change the engine rear oil seal.

SAFETY TIP OF THE MONTH:

Many times, when a fire starts, it is a surprise. But, the biggest surprise fire I ever experienced was the time I looked back, and the hayfield was on fire. I was cutting hay with a side cutter in a field that had scattered pebbles, and the sparks made from the blades hitting the pebbles set the field on fire. I thought for sure I had a hot bearing. Not this time. Be careful in extremely dry conditions and short dry hay. I now borrow the fire extinguisher off the round baler when I cut hay with the side cutter.

> Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email mechanic@progressivefarmer.com.

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