Diagnosing a Craftsman snowblower impeller not turning is pretty straightforward. This is generally a simple gear and belt driven system, so there’s not a lot of failure points. Let’s get into it.
Tools Needed (Commissions Earned)
Inspecting the Belt System
In a basic snowblower setup, power is driven from the crankshaft of the engine through a belt to the impeller pulley. When you depress the handle, a tensioner pulley applies tension to the belt which then drives the impeller pulley.
So for the first part of the diagnosis, inspect this system. It could be that the belt itself has snapped; it’s usually underneath a belt guard between the auger housing and the engine, and you can remove that with a couple of bolts for inspection.
While you’re under there, inspect the belt tensioner pulley. If it is worn or out of adjustment, it’s possible that when you depress the handle, the belt is just slipping because there’s not enough tension on the belt to overcome the resistance of the snow on the impeller.
Likewise, the belt could be slipping on the crankshaft pulley and the result is the same.
Over time, even a “normal” looking belt can stretch, and you can compensate by adjusting the tension on the tensioner pulley. Eventually, you’ll run out of adjustment room and you’ll have to replace the belt.
How’s the Tensioner Cable?
When you pull the handle to engage the impeller, a cable on the handle runs to the tensioner pulley. This cable can become stretched, broken or seized. While it might feel like you’re able to pull the handle, it might not be doing anything on the other end.
This will result in insufficient tension on the belt. With the belt guard off, depress the handle to ensure that the tensioner pulley is moving adequately and applying tension.
Inspect the Impeller Shear Pin
Inside the auger housing is (in a two stage snowblower) the impeller, the auger, and the gear box that transmits power from the impeller shaft to the auger.
For a point of clarification, a two stage snowblower has both an auger to draw snow in, and an impeller to blow it out. In a single stage snowblower, there’s only the auger.
A lot of snowblowers have the impeller keyed to the impeller shaft either on the front or the rear of the auger housing. Sometimes, there’s a shear pin in the impeller that’s designed as a sacrificial part.
Say that you hit a chunk of frozen ice or a rock that stops the machine dead in its tracks. The force of the auger suddenly halting has to go somewhere. Without the shear pin, that force is transmitted to the gear box.
This usually causes catastrophic damage, and the gear box is much more expensive to repair than a shear key, so that’s why they’re used.
If the key is sheared, then the impeller shaft will still be turning, and the auger might be (unless those pins also sheared) turning still, but the impeller won’t be. That’s a good indication that the shear pin did its job.
Also on this note, sometimes people replace a broken shear pin with a regular bolt. Unfortunately, a bolt isn’t designed to shear like an actual shear pin, so it might not. In this case, you might end up with that damage to the gear box. So use shear pins.
Look for Keyed Impellers
Regardless of if you have a shear pin, there might also be a keyed impeller shaft. This holds the impeller in place on the shaft so that it doesn’t spin freely. To that end, it functions similar to the shear pin, only, it’s not meant to shear.
That being said, it does happen sometimes – especially if you replaced the shear pin with a regular bolt.
If the key is sheared, then the impeller can spin freely. While the impeller shaft will be spinning, the impeller will not turn.
The symptom is similar to a sheared pin. With the machine off, you can freely spin the impeller on the shaft.
The only downside to this repair is that it’s more involved than a simple shear pin. If the shaft is keyed on the auger side of the housing, then you have to remove the auger and gearbox and pull the impeller shaft out the front after you’ve removed the impeller pulley from the rear of the housing.
I have seen it before where the impeller pulley is keyed to the shaft on the rear of the housing. In this case, you can just remove the pulley and replace the key.
What if the Auger is Not Turning?
The problems that cause an auger not to turn are similar to the impeller not turning. Usually, it’s a shear pin that’s broken.
The only difference between the auger and the impeller is that the auger relies on the gear box to transfer power. When the impeller is spinning but the auger isn’t, check the shear pins. If they’re not broken, then it’s possible that the gear box is damaged.
In that situation, you’ll have to remove the auger from the housing by following the aforementioned steps.
Then, you can remove the shear pins on the auger and slide the augers off. Pay attention to the direction the augers are facing. Yes, it is important.
They face a certain direction to pull snow into the machine. If you get it backwards, it won’t work right.
Once the augers are off, you can split the gear box apart to see where the failure is.
Recap
If you find your Craftsman snowblower impeller not turning (or any snowblower for that matter), inspect the belt system. Then, look for shear pins or sheared keys. This is usually a simple diagnosis to determine the failure point. Just remember to replace shear pins with actual shear pins to prevent future damage.
As an Amazon Associate I earn from qualifying purchases.