Few things are more aggravating than when your snowblower won’t turn over. You need it to clear the driveway in order to get to work, but in your moment of haste it doesn’t work. Let’s talk about some of the problems that can result in a snowblower not turning over. More importantly, let’s figure out how to fix it.
Tools Needed (Commissions Earned)
Snowblower Won’t Turn Over Diagnosis
I like to start any diagnosis with simple and move into more complex issues. More complexity usually equals more expensive repairs, and there’s no point in fixing something that isn’t broken.
If we start with the simple and ensure that those components are working correctly, then we can fix things as needed until we reach our final diagnosis.
That being said, there are a number of reasons that can cause a snowblower that won’t turn over.
Remove the Spark Plug
This can help you in two ways; first, it removes the compression to ease in turning the engine over. Secondly, it allows you access to the cylinder bore. Also, it prevents accidental ignition, so it’s safer.
If the combustion chamber has become flooded or vapor locked, the engine could possibly not turn over. Removing the spark plug is a good way to unflood the engine if that’s the case.
Also, as dumb as it sounds, if the wrong spark plug is installed it can actually hit the top of the piston at top dead center and prevent it from turning over.
Once the plug is removed, try to turn it over. Still stuck?
Try Lubricating the Bore
A light oil dribbled into the cylinder bore can help free the piston if the rings have seized to the cylinder wall. This typically doesn’t happen unless the machine has been sitting for some time or the cylinder has been exposed to water.
That being said, it does happen, so a little lubricating oil can help.
Inspect the Bore
I highly recommend a cheap borescope to inspect the bore without having to remove the head. It’s not difficult to remove the head, and it gives you an unobstructed view.
The only downside is that you should replace the head gasket. So if we can view the bore without removing the head, then that’s just one less step we have to do.
With the borescope inserted into the plug hole, take a look at the condition of the cylinder walls and the valves. Look for rust that could be seizing the piston.
Now that the bore has been lubricated, try rocking the flywheel back and forth incrementally. Once you break it free from the position that it’s been frozen in, make sure you keep lubricating the walls so as to not cause further damage.
The last thing we want is to have a piece of rust score the cylinder walls, so try to flush it.
If the borescope inspection reveals heavy damage or rust, then your best bet is to remove the head to thoroughly clean the head, valves and cylinder walls.
If there’s scoring on the walls, then you’ll want to disassemble the engine completely in order to hone the cylinder. This isn’t as bad as it sounds. With scratches on the cylinder wall, the piston rings can’t seal correctly and the end result is a loss of compression.
Even if you were to get the engine running, it will be underpowered as it is lacking adequate compression.
Assuming these steps don’t free up the engine, then you have to resort to the final step.
Remove the Head
Like I mentioned, it’s not difficult to remove the head; just remove the bolts and tap the head off.
From here, you can take a direct visual inspection. It’s possible that the piston is seized, or maybe a valve is stuck. Or, it could be a broken connecting rod. At this point, the only way to tell is to remove the head.
Once it’s off, turn the flywheel over and see if you get any play in either direction.
Use the valve spring compressor to remove the valves and inspect them for warping. If an engine overheats, the valves can bend and get stuck.
More commonly, lack of maintenance or use can result in the valves getting stuck in the seat. Simply cleaning the valves can fix this issue.
For cleaning the head and the valves, I like to use a brass wire wheel as it’s soft enough to not score the surfaces.
If you find that rust is holding the piston to the cylinder wall, then it’s probably safe to assume that the cylinder is toast.
You can remove the connecting rod from the crankshaft and try to tap the piston down and into the block.
If you’re able to remove it this way, then it’s possible to clean the rust by honing, but it’s not likely.
Recap
If your snowblower won’t turn over, assess if it’s flooded by removing the spark plug and trying to turn it over. Lubricate the bore and try to inspect it with a borescope. Finally, remove the head to do a thorough assessment for the cause.
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