Snow Blower Auger Not Turning or Throwing Snow? Shear Pin, Belt and Chute Checks
Short answer: if the engine runs but snow is not coming out, the cause is usually one of five things. Toro's troubleshooting table lists them for "engine runs, but the machine discharges snow poorly or not at all". The throttle is not on Fast, you are moving too fast or taking too big a bite, the snow is extremely heavy or wet, the chute is plugged, or the auger/impeller belt is loose, off its pulley, worn or broken. On two-stage machines a broken shear pin is the other classic cause: the engine and impeller run, but one or both auger halves just sit there.
Work through the checks below from easiest to hardest. Before you touch anything near the auger, chute or belts, stop the engine, wait for all moving parts to stop and remove the key. Toro's manual tells you to clear the chute with a stick, never your hand. A clogged chute can hold tension in the impeller, and snow blower chute injuries are common for that reason.
Step 1: rule out operator settings (1 minute)
From Toro's table:
- Throttle not on Fast. Snow blowers are meant to throw snow at full engine speed. Move the throttle to Fast.
- Moving too fast. Shift to a lower gear so the auger can keep up.
- Taking too much per pass. Reduce the width or depth of each pass.
- Extremely heavy or wet snow. Slow down and take partial passes. Toro lists heavy, wet snow as a cause on its own.
If the auger is visibly turning but throwing weakly, the problem is probably one of these four or the chute.
Step 2: clear the chute and housing
A plugged discharge chute is on Toro's list. Wet snow packs into the chute and impeller housing, and it can freeze there overnight.
- Stop the engine, wait for everything to stop moving and remove the key.
- Use a clearing tool or stick to break up the packed snow in the chute and around the impeller. Never use your hand.
- Before you start, check that the auger and impeller are free to turn and not frozen. Toro's older manual asks for this check before every start.
- When you finish clearing, Toro suggests engaging the auger for a moment to clear remaining snow from the housing. That helps stop a re-freeze before the next storm.
Step 3: check the shear pins (two-stage machines)
Ariens explains that shear pins are designed to break on purpose when the auger hits something solid, such as a newspaper, ice chunk or landscape edging. The pin breaking protects the more expensive gearbox and auger parts.
Signs of a broken shear pin:
- The engine and impeller run, but one side of the auger does not turn, or neither side does.
- You heard a bang or clunk just before it stopped throwing.
- You can see an empty hole, or half a pin, where the auger joins the shaft.
Replace broken pins with the correct shear pins for your model, not ordinary bolts. A hardened bolt will not shear, and the next impact goes into the gearbox instead. Step-by-step replacement with a diagram is in our shear pin replacement guide.
Step 4: inspect the auger/impeller belt
Toro lists two belt causes: the auger/impeller belt is loose or off the pulley, and the belt is worn or broken.
Signs it is the belt:
- The engine runs at full speed but neither the auger nor the impeller turns, or they slow right down under load.
- A burning rubber smell or squeal when you engage the auger.
- Black dust around the belt cover.
What to look for, with the engine off and the key removed:
- Remove the belt cover (usually a few screws on the front of the engine side).
- Check that the belt is seated on the pulleys.
- Look for cracks, glazing (a shiny, hardened surface) or fraying. Cub Cadet's off-season checklist uses the same three signs.
- Check the belt has tension when the auger control is held. Many machines use an idler pulley that tightens the belt only when the control is engaged.
A belt that has come off once will come off again unless the cause is fixed. That could be a worn belt, a damaged pulley or a cable that needs adjusting. Belt replacement and cable adjustment are model-specific, so follow your operator's manual or have a dealer do it. If you replace the belt yourself, use the exact part number in your manual, because similar-looking belts differ in length and profile.
Step 5: single-stage machines are different
A single-stage snow blower has a rubber-paddled auger that both picks up and throws the snow. There is no separate impeller, and usually no shear pin. If it throws poorly:
- Worn paddles are the first thing to check. Cub Cadet's storage checklist tells you to inspect the rubber auger paddles and replace them if worn.
- Check the belt, as above.
Step 6: when to stop and call a dealer
Take it in if:
- The shear pins and belt are fine but the auger still does not turn. That suggests the gearbox.
- The auger turns by hand when it should not, or it grinds.
- The belt keeps coming off after you replace it.
Prevent it
- Walk the area before the first snow and pick up newspapers, doormats, extension cords and stones. They are what break shear pins.
- Keep spare shear pins and the matching nuts in a bag tied to the handle.
- At the end of winter, inspect the belts, paddles and shear pins as part of your off-season storage checklist.
- If the engine itself is the problem, see why a snow blower won't start in the cold.
All of our winter guides are listed under Snow Blowers.
FAQ
Why does my snow blower run but not throw snow?
Toro lists these causes: throttle not on Fast, moving too fast, taking too much at once, very heavy wet snow, a plugged chute, or a loose, off, worn or broken auger/impeller belt. On two-stage machines, also check the shear pins.
Only one side of my auger is turning. What is wrong?
Usually a broken shear pin on that side. Each auger half is pinned to the shaft separately on most two-stage machines.
Can I use a regular bolt instead of a shear pin?
No. Shear pins are designed to break and protect the gearbox. A regular bolt will not break, so the damage moves to more expensive parts.
How do I know if the auger belt is bad?
Look for cracks, glazing or fraying, a belt that is off its pulley, or a burning smell when the auger is engaged.
Is it safe to clear a clogged chute with the engine off?
Only with the engine stopped, all parts still and the key removed, and only with a stick or clearing tool, never your hand.
Sources
- Toro Interactive Operator's Manual (two-stage snow blower, form 254533), Troubleshooting: https://manuals.toro.com/254533/index.html
- Toro Operator's Manual (pre-start auger/impeller check, clearing with a stick): https://www.toro.com/getpub/4443
- Ariens, "What Are Shear Pins and Why Do I Need Them?": https://www.ariens.com/en-us/company/blog/277/what-are-shear-pins-and-why-do-i-need-them
- Cub Cadet, "How to Prepare Your Snow Blower for Storage in the Off-Season": https://www.cubcadet.com/en_US/knowledge-center/knowledge-how-to-prepare-your-snow-thrower-for-storage-in-the-off-season.html