Lawn Mower Shakes Violently When Blades Engaged [Fixed]

Lawn Mower Shakes Violently

There are several reasons why lawn mower shakes violently when blades engaged! By reading this troubleshooting guide, you will not only able to identify the causes, symptoms, and effects of a shaking lawnmower but also be capable of fixing the shaking and vibrating issues of your lawnmower.

One possibility is that the blade is damaged or unbalanced. If the blade is damaged, it can cause the mower to vibrate excessively. The engine might be tuned too lean, which will cause the mower to vibrate heavily. Moreover, the blade could be installed incorrectly, which can also cause the mower to vibrate excessively.

Therefore, the major causes behind this vibrating issue can be the blades or a crankshaft. If you’re experiencing shaking or waving issues with your ride, don’t worry! Simply read the user manual to find out how these symptoms can be fixed.

But in case of emergency – like if it’s critical for safety- our guide will help get things back on track quickly so that no one is injured.

Why Lawn Mower Shakes Violently When Blades Engaged?

The first step in fixing a vibrating lawnmower is to identify the exact causes and reasons behind it. We need this information so we can tackle the main cause of the problem, then head toward solving it!

There are certain possibilities that might cause your lawnmower to vibrate;

  • Unbalanced blades
  • Pollute blades
  • Unsharpened blades
  • Bent Crankshaft

Let’s take a look at each issue one by one to get the answer and fix our main problem: why does your lawnmower shake violently when blades are engaged?

1. Unbalanced Blades

When the blades move at speeds over 200 mph, they can shake and rattle even if you have them balanced correctly. This is because there’s no depth to their contact with one another – it just sounds like noise!

The lawnmower will likely be more unstable when sharpened incorrectly or not reinstalled properly after being sharpened so make sure your blade has good placement in each wheel before using it again.

Balancing blades

Sometimes when blades strike some hard material (stone, rock, or hard root) on the ground, it can also disbalance the blades or any other damage to them.

Balancing Blades

You need to;

  • Replace the damaged or unbalanced blades immediately.
  • Reinstall the blades properly.
  • Try to sharpen the blades on both sides to keep them evenly balanced by removing the extra metal from them.

Replacing the Blades

  • You can easily replace or remove the blades by using the user manual.
  • Tilt the lawnmower to prevent fuel leakage and to keep the carburetor up.
  • Drain the excess fuel if needed, just to prevent fuel or oil from leaking through gaps.
  • Use a spanner for the safe and secure removal of blades.
  • Clean the blades thoroughly after removing them from the deck.
  • Use a torque spanner of accurate size to install new blades and to harden them well.
Mulching Blades
Item Weight: 4.78 pounds
Dimensions: 24.5 x 3 x 1.25 inches
Compatibility: Craftsman, Husqvarna, and Poulan mowers

2. Polluted Blades

If you are experiencing a vibrating lawnmower, it could be due to an obstruction in the blade. You should remove any clumps or mud from your blades before starting up so that there is no weight on them when running over grass surfaces!

polluted blades

How to Fix Polluted Blades – Why Lawn Mower Shakes Violently

You can simply fix the pollute blades by;

  • Untie blades from the deck.
  • Make sure to clean them thoroughly with water, brush, and cloth if needed.
  • Reinstall them properly using a spanner and the user manual.

3. Unsharpened Blades

When you have had long mowing sessions, your blades need to be sharpened and maintained. By cutting a huge amount of grassroots and debris in one go they become rough with dirt which will dull their efficiency over time if not taken care of properly.

Maintaining the lawn equipment can help ensure that everything remains running smoothly so no more problems occur.

Unsharpened blades

How to Fix Unsharpened Blades – Why Lawn Mower Shakes Violently

  • You may need to check the balance of the blades while sharpening them.
  • For this purpose, you might need some devices to check and to keep them evenly balanced.
  • You can simply fasten the blade through the center hole on a peg or a nail in a wall.
  • The heavy side will drop lower than the other side.
  • Try continuous sharpening by removing extra metal, till the blades become stable and come to an equilibrium position.
Blade Sharpner Kit
Item Weight: 0.75 pounds
Dimensions: 4.33 x 4.13 x 3.15 inches
Compatibility: Specifically designed to tackle even the dullest blade.

4. Bent Crankshaft

The bent crankshaft is another major cause of excessive vibration and shaking during mowing. The blades, as well as the engine itself, can get damaged from tapping or striking a lawnmower with some hard material too much- this will result in a misaligned blade which then causes more wear on your motor over time!

Bent Crankshaft

When the lawnmower vibration is combined with an improperly aligned crankshaft, it can cause this problem. And sometimes stopping suddenly on a wet blade could bend them enough to make their shape noticeable by feel or sight in addition to the loud noise that you’ll hear when driving through town!

How to Diagnose the Damaged Crankshaft

  • Remove the first possible cause of vibration, which is blades.
  • Run the mower without blades and be careful to notice the sound and the shaking after their removal.
  • If the lawnmower is again vibrating then it can cause by the damaged crankshaft.
  • The next step is the removal of shaking causes.

How to Fix Damaged Crankshaft- Why Lawn Mower Shakes Violently

You can simply repair or fix the damaged crankshaft by following the mentioned steps;

  • After removing the blades, it is necessary to check the crankshaft runout by using a dial indicator.
  • Eliminate the blades along with the blade mounting core and the spark plug from the lawnmower.
  • Attach the dial indicator to the deck and placed it on the crankshaft.
  • Carefully read the amount of runout on the indicator by gently twisting the engine.
  • Therefore, the value over .003″ verifies the crankshaft damage.
  • You can concern the user manual for the exact value according to your lawnmower.
  • You need to remove the complete engine step by step to replace the bent crankshaft.
  • Hire some professionals to service your engine and the lawnmower to avoid excess damage.
Crankshaft Straightner
Item Weight: 1.12 pounds
Dimensions: 25 x 15 x 10 inches
Average Time: 7 minutes

When your lawnmower shakes uncontrollably, it can be quite alarming. However, with some knowledge of what causes this behavior and how to fix or repair the problem, you will no longer need to worry about being shocked at every turn!

Ignoring the vibration will lead you and the lawnmower to major mechanical or technical issues which sometimes are difficult to handle for an inexperienced person.

Follow this simple guide to diagnose the issue of excessive and violent vibration and try to fix it the way this guide teaches you. Otherwise, hire some professionals to tackle, handle, and fix the issue without making it severe.

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