The flywheel key is a metal piece that fits into a notch on the flywheel. The key keeps the flywheel from moving on the crankshaft. The key can shear off if the bolt that holds it in place comes loose, or if there is too much pressure on the key while starting the engine.
A sheared flywheel key is one of the most common causes of engine failure. The flywheel key is a small, but important, piece of metal that fits into a slot in the flywheel. The key keeps the crankshaft from moving forward and backward, and also keeps the Flywheel from spinning on the shaft.
Over time, the key can become worn down and eventually break. This will cause the engine to lose power and eventually stall. In some cases, a sheared flywheel key can also cause damage to other engine parts.
How To Prevent a Flywheel Key from Shearing
Sheared Flywheel Key Symptoms
If you notice any of the following symptoms, your flywheel key may be sheared: – Your engine will not start – Your engine will stall unexpectedly

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What Could Cause a Sheared Flywheel Key?
If your engine’s flywheel has a sheared key, it means that the key that connects the flywheel to the crankshaft has broken. This can be caused by several things, but the most common cause is simply wear and tear. Over time, the key can become worn down, especially if the engine is not properly maintained.
Other causes of a sheared flywheel key include damage from an impact (such as a car accident) or excessive heat (from overheating). Whatever the cause, a sheared flywheel key is a serious problem that should be fixed as soon as possible.
If you suspect that your flywheel key may have sheared, the first thing you should do is check for any signs of damage.
If you see any cracks or chips in the flywheel or crankshaft, then it’s likely that the key has already failed. In some cases, you may also be able to feel play in the connection between the two parts. If there is any movement at all, then it’s almost certain that the key has sheared and needs to be replaced.
What Happens If Flywheel Key is Sheared?
If the flywheel key is sheared, it will no longer be able to properly engage with the crankshaft. This can cause the engine to misfire, or not run at all. In some cases, the engine may also seize up if the flywheel key shears.
How Do You Remove a Sheared Flywheel Key?
If your flywheel key shears off, it can be a real pain to remove. Here are a few tips on how to remove a sheared flywheel key:
1. First, take a look at the broken key and see if you can identify where it broke.
If you can’t, don’t worry – we’ll get to that in a minute.
2. Next, use a hammer and punch to drive the broken key out of the flywheel. Start from the outside and work your way in until the key pops out.
3. If you can’t get the broken key out with a hammer and punch, you may need to resort to using an angle grinder or other power tool to cut it out. Be very careful not to damage the flywheel while doing this!
4. Once the broken key is removed, you’ll need to replace it with a new one before reassembling everything.
Make sure that the new key is properly seated in the flywheel before continuing!
What is the Main Purpose of the Flywheel Key?
The main purpose of the flywheel key is to keep the crankshaft from rotating on the engine. It also keeps the timing belt or chain from slipping. The flywheel keyway is a slot cut into the circumference of the flywheel.
The key is a small metal shim that fits into this slot. When installed, it prevents the crankshaft from moving relative to the flywheel.
Conclusion
The flywheel key is a small, but important, piece of metal that helps to keep your engine in sync. It’s located on the outside of the flywheel and fits into a slot on the crankshaft. The key keeps the flywheel from moving independently of the crankshaft.
Unfortunately, the flywheel key can shear off if there’s too much vibration or stress on it. This can happen if you hit a big bump while driving, or if your engine isn’t properly balanced. If the key shears off, it can cause serious damage to your engine.
If you think your flywheel key may have sheared off, it’s important to get it checked out by a mechanic as soon as possible. They’ll be able to tell for sure and make any necessary repairs.