Small Engine / Winter
Snow Blower Wear Parts: Shear Pins, Skid Shoes, Scraper Bars and Belts
Snow blowers spend most of the year forgotten in a shed, then get asked to work hard on the coldest mornings. When one quits mid-driveway, the culprit is often a small wear part rather than the engine: a snapped shear pin, a worn scraper bar, a slipping belt. Knowing which parts wear, how to identify the right replacements, and what to keep on the shelf can save a winter weekend.
The rule that comes before every repair
Snow blower chute and auger injuries are a well-known winter hazard. Shut off the engine, disengage the controls, wait for all moving parts to stop, and clear snow with a clearing tool or stick, never your hand. Even with the engine off, the auger and impeller can hold tension and move when a clog is released. Remove the spark plug wire before working near the auger.
Know your machine type
Which parts wear depends on the design:
| Type | How it works | Main wear parts |
|---|---|---|
| Single-stage | A rubber-edged auger scoops snow and throws it out the chute in one motion; the auger contacts the pavement and helps pull the machine | Auger paddles, scraper bar, drive belt, spark plug |
| Two-stage | A metal auger feeds snow to a fast impeller that throws it; self-propelled wheels or tracks | Shear pins, scraper bar, skid shoes, auger and drive belts, friction wheel |
| Three-stage | Adds an accelerator between auger and impeller to break up heavy snow | Same as two-stage, plus accelerator components |
Before you buy any part, find the model and serial number plate, usually on the frame or behind the auger housing. Parts lists are organized by model, and many brands change parts between production runs. Our guide to decoding small engine model numbers helps with the engine side.
Shear pins: the part designed to fail
On most two-stage and three-stage blowers, the auger is attached to its drive shaft with shear pins (or shear bolts). If the auger hits something it can't throw, like a frozen newspaper, a chunk of ice from the plow pile, or a landscape stone, the pins break so the auger stops instead of the gearbox, shaft or auger taking the shock.
Signs a shear pin has broken
- The engine runs and the impeller throws a little snow, but one side of the auger doesn't turn
- The auger spins freely by hand on one side (with the engine off and spark plug wire removed)
- Snow builds up in front of the housing instead of being drawn in
Replacing them
- Shut off the engine, remove the key and the spark plug wire, and let everything stop.
- Line up the holes in the auger and the shaft. Tap out any remaining piece of the broken pin.
- Insert the correct replacement pin and secure it with its nut or clip.
- If the auger has been freezing to the shaft, check your service manual for how to lubricate the shaft so the pins can work as intended.
Shear pins are engineered to break at a specific load. A stronger bolt won't break, which means the next impact goes into the gearbox instead. Gearbox repairs are much more expensive than a pack of pins. Buy pins listed for your model and keep spares taped to the handle or in a pouch on the machine.
Scraper bars and skid shoes
Scraper bar
The scraper bar is the replaceable strip along the bottom of the auger housing. It scrapes the pavement and protects the housing itself. Some are steel; some are polymer that's gentler on decorative surfaces. Many steel bars can be flipped to use the second edge before replacement. Replace it when it's worn close to the housing, cracked, or no longer clears down to the surface.
Skid shoes
Skid shoes are the adjustable pads on each side of the housing. They set how high the scraper bar rides:
- Paved driveways: Lower the shoes so the scraper bar clears close to the surface.
- Gravel or uneven surfaces: Raise them so the auger doesn't pick up and throw stones, which can damage the machine, windows, and people.
Steel shoes are durable; composite or poly shoes are quieter and kinder to pavers and decorative concrete. Some owners use roller-style skids for smoother travel. Adjust both sides evenly and check them after the first few uses.
Single-stage owners: the rubber auger paddles do the scraping and also help pull the machine forward. Replace them when they're worn enough that the machine leaves a layer of snow behind or no longer pulls itself along.
Belts and the friction drive
Most two-stage machines use two belts: one drives the auger and impeller, the other drives the wheels or tracks. A worn auger belt slips under load, so the engine bogs while the auger slows down. A worn drive belt makes the machine stall on inclines or in heavy snow.
Snow blower belts are often specific to the model and may be reinforced for clutching duty, so match by part number rather than size alone. If the part number is gone, our guide to measuring and cross-referencing drive belts explains how to measure, though an OEM-spec belt is the safest choice for a snow blower.
Many self-propelled machines use a friction drive: a rubber-tired friction wheel that presses against a metal drive plate. Water, oil or glazing on the friction wheel causes slipping. If the drive engages weakly or not at all, inspect the friction wheel for wear and contamination. Belt and friction wheel replacements are reasonable DIY jobs with the service manual; if you're unsure, a small engine shop can handle them.
Engine parts to check before winter
Snow blower engines suffer from the same off-season problems as mowers, just in reverse. Fuel left in the tank all summer is a common reason a blower won't start in December.
- Fuel: Start the season with fresh fuel and use a stabilizer for anything that will sit. Ethanol blends absorb moisture and can gum up small carburetors; see our ethanol and small engines guide and our fuel stabilizer picks.
- Spark plug: Inspect it and replace it if it's fouled or worn. See our small engine spark plug guide.
- Oil: Change it per the manual and use the viscosity the manufacturer specifies for cold weather.
- Carburetor: If the engine surges or only runs on choke, the carburetor may need cleaning or a rebuild kit.
- Electric start: If your machine has a plug-in electric starter, inspect the cord before use and plug into a grounded outdoor outlet.
Pre-season snow blower checklist
- Spare shear pins for your model on hand
- Scraper bar has edge left (or has been flipped)
- Skid shoes adjusted for your surface
- Auger and drive belts free of cracks and glazing; tension correct
- Friction wheel rubber in good shape and dry (if equipped)
- Chute rotates and deflector moves freely; cables intact
- Auger gearbox lubricated as the manual specifies
- Fresh fuel, stabilizer, fresh oil, good spark plug
- Tires inflated or tracks in good condition
- Clearing tool attached to the machine
- Driveway hazards marked before the first snow
At season's end, the reverse process matters too. Our small engine storage guide covers fuel and storage prep that applies to snow blowers in spring.
Frequently asked questions
Why do my snow blower shear pins keep breaking?
Common causes include hitting hidden objects, ice chunks from plow piles, an auger that has seized to its shaft, or pins that aren't the correct spec. Check the shaft for corrosion and lubricate as the manual specifies, and mark hidden obstacles before snowfall.
Can I use a regular bolt instead of a shear pin?
No. A standard bolt is often stronger than the shear pin, so it won't break when the auger jams, and the force can damage the gearbox instead. Use the pins listed for your model.
Should skid shoes be up or down on a gravel driveway?
Raise them so the scraper bar rides above the gravel. This keeps the auger from picking up stones and throwing them, which can damage the machine and is dangerous to people and windows.
How do I know if my snow blower belt is bad?
Signs include the auger slowing or stopping under load while the engine runs, the machine struggling to move itself, a burning rubber smell, or visible cracks, fraying or glazing on the belt.
Is it safe to clear a snow blower chute with the engine off?
Only with a clearing tool, after the engine is off and all parts have stopped. The auger and impeller can still move when a clog releases, so never use your hands.
Bottom line
Most snow blower breakdowns come down to a few wear parts. Keep the correct shear pins on hand, set the skid shoes for your surface, replace the scraper bar and belts before they fail, and start the season with fresh fuel. Above all, never clear a clog by hand.
For more outdoor power equipment help, see the small engine parts guide, browse the Parts Catalog blog, or start from the Small Engine category.