Snow Blower Shear Pins: Why They Break and How to Replace Them
If your snow blower's engine runs but the auger stops turning, the most likely cause is a broken shear pin. That's not a failure; it's the pin doing its job.
What a shear pin does
Shear pins (sometimes called shear bolts) hold the auger to the auger shaft on two-stage snow blowers. They're made to snap when the auger hits something solid, like a frozen newspaper, a rock or a chunk of ice. Breaking the cheap pin protects the expensive parts: the auger gearbox, shaft and belt.
Why you should never use a regular bolt
A standard hardware-store bolt is often stronger than a shear pin. It won't break when the auger jams, so the force goes into the gearbox instead. That can turn a $5 repair into a several-hundred-dollar one. Always replace shear pins with the correct pins for your machine.
Signs a pin has sheared
- The engine runs and the impeller throws snow, but the auger doesn't turn (or only one side turns)
- You heard a loud bang or clunk just before it stopped
- You can see a missing or broken pin where the auger meets the shaft
How to replace a shear pin
- Shut off the engine, remove the key and disconnect the spark plug wire. Never reach into the auger housing with the engine running.
- Clear any snow, ice or debris from the auger, and remove whatever caused the jam.
- Remove the broken pieces of the old pin. A punch and hammer help if a piece is stuck.
- Rotate the auger until the hole in the auger lines up with the hole in the shaft.
- Slide in the new shear pin and fasten it with its nut or clip. Snug it; don't overtighten.
- Reconnect the spark plug wire and test the auger.
Tips
- Keep spares on the machine. Many snow blowers have a spot on the handle or dash to store extra pins. Buy a multi-pack so you're never stuck mid-storm.
- Lubricate the auger shaft at the start of the season. A rusted auger that can't spin freely on the shaft can stress pins and the gearbox.
- Match the pin to your brand and model. Pins differ in length, diameter and strength. Use the OEM part number from your manual.
Shop snow blower shear pins and other snow blower parts, including scraper bars, skid shoes and paddles.