Snowblower Auger Stops in Snow? The #1 Hidden Cause to Check NOW

There’s nothing more frustrating than wheeling your snowblower out to tackle a fresh blanket of snow, only for the auger to give up the moment it bites into the drift. The engine roars, the wheels turn, but the critical part of the machine—the auger—stops dead in its tracks. You’re left with a heavy, noisy machine that’s doing little more than pushing snow around.

This common and infuriating problem can bring your snow clearing efforts to a screeching halt. Fortunately, the solution is often simple and inexpensive. This guide will walk you through the most common causes and provide step-by-step instructions to get your snowblower back to powerfully throwing snow.

The Prime Suspect: Why Shear Pins Are Your First Check

Before you start worrying about expensive repairs, the very first component to inspect is the shear pin. In fact, a broken shear pin is the most common reason an auger stops spinning under load. It’s a small, yet vital, piece of engineering designed to be the weakest link.

What is a Shear Pin and Why Does it Break?

A shear pin, also known as a shear bolt, is a small metal pin that connects the auger to the auger shaft which is turned by the engine. Its sole purpose is to break, or “shear,” under excessive stress. This is a deliberate safety feature designed to protect the expensive and powerful gearbox and engine from damage.

If the auger hits a hard object like a rock, a thick piece of ice, a frozen newspaper, or even a child’s toy hidden under the snow, the sudden stop could cause catastrophic damage to the transmission. Instead, the shear pin snaps, disconnecting the auger from the driveshaft and allowing the engine to continue running without destroying itself.

Symptoms of a Broken Shear Pin

The classic symptom of a broken shear pin is an auger that spins freely when there’s no snow but stops the second it comes under load. You may even be able to spin one of the auger blades by hand while the other remains stationary. If you hear the engine running fine but the snow isn’t being thrown, a broken shear pin is the most likely culprit.

How to Inspect and Replace a Shear Pin

Replacing a shear pin is a quick and easy job that every snowblower owner should know how to do. Always keep a few extra shear pins on hand; they are inexpensive and will save you a major headache in the middle of a storm.

Safety First: Before performing any inspection or maintenance, turn off the snowblower, remove the ignition key, and disconnect the spark plug wire. This prevents any possibility of an accidental startup.

1. Locate the Shear Pins: You will find the shear pins located on the auger shaft, typically one on each side, securing each auger blade assembly to the central shaft.
2. Inspect for Damage: Look closely at the pins. A broken pin will be sheared in two, and half of it may have already fallen out. If a pin is missing or you see a clean break, you’ve found the problem.
3. Remove the Broken Pin: If a piece of the pin is stuck in the hole, you may need to use a punch or a small screwdriver and a hammer to gently tap it out. Aligning the hole on the auger with the hole on the shaft is key.
4. Install the New Pin: Slide the new shear pin through the aligned holes. Secure it on the other side with the corresponding cotter pin or nut that it came with. Do not overtighten the nut, as this can stress the pin and cause it to fail prematurely.
5. Use the Correct Part: It is critical to use only the manufacturer-specified shear pins for your model. Using a standard bolt is incredibly dangerous, as it will not shear as intended and can lead to severe damage to your snowblower’s gearbox.

Is Your Auger Belt the Hidden Problem?

If your shear pins are intact, the next most likely cause is a problem with the auger drive belt. This belt transfers power from the engine to the auger pulley. Over time, these rubber belts can stretch, crack, glaze over, or break entirely.

Telltale Signs of a Worn-Out Auger Belt

A failing belt often gives warning signs before it completely breaks. You might hear a high-pitched squealing sound when you engage the auger, or you might smell burning rubber. Another key symptom is if the auger engages slowly or seems to lack the power it once had, especially in heavy, wet snow. Knowing how much snow is too much for your machine can prevent premature belt wear.

Step-by-Step Guide: Inspecting and Adjusting the Auger Belt

Again, ensure the engine is off, the key is removed, and the spark plug is disconnected.

1. Access the Belt Cover: The belts are located behind a plastic or metal cover, usually between the engine and the auger housing. You will need to remove a few bolts or screws to take this cover off.
2. Visually Inspect the Belt: Look for cracks, fraying, glazing (a shiny, smooth surface), or missing chunks. Any visible damage means the belt needs to be replaced.
3. Check the Tension: When the auger handle is engaged, the belt should be tight. A tensioner pulley is what applies this pressure. If the belt feels loose or deflects more than about half an inch with pressure from your finger, it may need adjustment.
4. Adjust the Tensioner: Many models have an adjustable idler pulley or a cable that can be tightened to increase belt tension. Consult your owner’s manual for the specific procedure for your machine, as this can vary. Tightening a stretched cable or moving the idler pulley can often restore proper function.
5. Replace the Belt if Necessary: If the belt is damaged or stretched beyond the limits of adjustment, it must be replaced. This process typically involves loosening the tensioner, routing the old belt off the pulleys, and carefully installing the new one.

Beyond the Basics: Other Potential Causes

While shear pins and belts account for the vast majority of cases, there are a few other issues that can cause your auger to stop under load. Some vintage models, like the famously durable TRS27 John Deere, have robust systems, but even they are susceptible to wear and tear over time.

Stretched or Broken Engagement Cable

The auger engagement lever on your handlebar is connected to the tensioner pulley via a cable. If this cable stretches over time, it won’t be able to pull the tensioner pulley far enough to properly tighten the belt. In some cases, the cable itself can snap. You can often adjust the cable’s tension where it connects to the handle or the engine housing.

Impeller and Chute Clogs

The auger feeds snow to a high-speed fan called an impeller, which then throws it out of the chute. If the chute becomes clogged with heavy, wet snow or ice, it can back up the entire system. This blockage can create enough resistance to stop the auger from turning. Safely clearing the chute and impeller (with the engine OFF) can resolve the issue. For persistent clogging, an Ariens snowblower chute modification or a similar upgrade can significantly improve performance.

Rusted Auger Shaft

An often-overlooked issue, especially on machines stored in damp conditions, is rust buildup between the auger tubes and the main auger shaft. The augers are designed to “float” on the shaft, held in place only by the shear pins. If rust forms, it can effectively seize the auger to the shaft. When this happens, the shear pin can’t do its job, and the rotational force is transferred directly to the obstruction, which can stall the engine or, worse, damage the gearbox.

Problem	Key Symptom	DIY Difficulty	Primary Solution
Broken Shear Pin	Auger stops under load but spins freely by hand.	Easy	Replace the shear pin.
Worn/Loose Auger Belt	Squealing noise, burning smell, slow auger engagement.	Moderate	Adjust tensioner or replace the belt.
Stretched Engagement Cable	Auger handle feels loose; auger doesn’t engage fully.	Easy to Moderate	Adjust cable tension at handlebar or engine.
Clogged Chute/Impeller	Snow packs up and doesn’t exit the chute.	Easy	Safely clear the obstruction (engine OFF).
Rusted Auger Shaft	Auger feels stiff or seized even with shear pins removed.	Difficult	Disassemble, clean, and lubricate the shaft and auger tubes.
Failed Gearbox	Grinding noises, auger won’t turn but impeller shaft does.	Very Difficult	Professional repair or gearbox replacement.

Preventative Maintenance: Stop Problems Before They Start

The best way to deal with a broken snowblower is to prevent it from breaking in the first place. A little pre-season maintenance goes a long way in ensuring reliability all winter.

Annual Auger System Checklist

Before the first snowfall, take an hour to perform these critical checks.

• Inspect and Replace Old Shear Pins: Don’t wait for them to break. If they look rusty or stressed, replace them as a preventative measure.
• Check Belt Condition and Tension: Remove the belt cover and give the belts a thorough inspection. Adjust tension as needed. If a belt is over five years old, consider replacing it even if it looks okay.
• Lubricate the Auger Shaft: A critical but often forgotten step. Remove the shear pins and ensure both auger halves spin freely on the shaft. Applying a coat of marine-grade grease or anti-seize compound to the shaft will prevent rust and ensure the shear pins can function correctly.
• Check All Fasteners: The vibration of the engine can loosen bolts over time. Check that the bolts on the auger housing, scraper bar, and skid shoes are tight.

When to Call a Professional

While most auger issues are fixable at home, some problems are best left to a qualified small engine mechanic. If you’ve checked the shear pins and the belt system and everything seems to be in order, but the auger still won’t turn under load, you could be facing a more serious internal issue.

Signs of a failed gearbox include loud grinding or clunking noises coming from the auger housing. You may also find that the input shaft going into the gearbox spins, but the auger shaft itself does not. Gearbox repairs are complex and require specialized tools, making it a job for the pros.

Don’t let a stalled auger defeat you this winter. By following these diagnostic steps, you can quickly identify the problem, perform the necessary repair, and get back to clearing snow with confidence. A small investment in time and a few spare parts can ensure your machine is always ready for the storm.