Cub Cadet Riding Mower Loses Power When Blades Are Engaged

When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

If your Cub Cadet riding mower loses power when blades are engaged, it can be quite frustrating especially if you have a lot of work to do with it.

The problem may arise as a result of a worn Cub Cadet mower belt, faulty spark plug, bad pulleys and worn-out spindles.

In this article, I look at 12 possible reasons why your Cub Cadet mower loses power when blades are engaged. And some proven troubleshooting tips that can help you solve the issue. 

Reasons Why Your Cub Cadet Riding Mower Loses Power When Blades Are Engaged

Some of the reasons why your zero-turn may lose power when blades are engaged may include:

  • Defective spark plug
  • Dull blade
  • Blocked muffler 
  • Worn out blade spindle bearings
  • Loose/worn Cub Cadet mower belt.
  • Dirty carburetor
  • Dirty underside

Tools You Need for This Job

  • 15/16-inch socket or wrench.
  • Gloves
  • Container
  • Blade removal tool 
  • Block of wood
  • 9/16-inch socket or wrench

Cub Cadet Riding mower Loses Power When Blades Are Engaged: Possible Causes and Fixes

1.  Dull Blade

When the blade is dull, it has to work harder to mow through the grass which can cause the mower engine to lose power when blades are engaged. 

This will further affect the functionality and performance of your Cub Cadet mower.


  • Inspect the blades to see if they are dull.  


How To Replace The Blade on Your Cub Cadet Riding Lawn Mower


Here are some tips on how to replace your Cub Cadet riding lawn mower blade:

Step One

Put your mowing machine on a level and flat surface. Shut off your mower and ensure that the mower engine is cool.

Take off your ignition key, detach your spark plug ignition cable, and engage your parking brake. This will prevent your mower from starting accidentally.

Step Two

Place the deck height of the mower in the lowest position

Step Three

Take off your drive belt from the engine pulley. Make use of a wrench or a 9/16-inch  socket to pull the mower’s idler pulley arm to the forward position so that it can release the belt tension.

Step Four

Ensure that you detach three cotter pins and release the deck pins that hold the mower deck of your Cub Cadet mower.

If you own a Cub Cadet riding mower model  that features a manual PTO,  ensure that you  disconnect the PTO cable before removing your mower deck.

After removing the pins, you can now slide out the cutting deck from underneath the mowing machine.

Step Five

To have access to the blades, carefully flip the mower deck over. Make sure that you wear gloves to offer safety.

A blade removal tool or block of wood can be used to prevent the rotation of mower blades. To loosen the nuts of the blade, you need to use a 15/16-inch socket or wrench.

Step Six

Change the blades carefully and ensure that the nuts are tightened securely as specified in the owner’s manual. 

If it is rightly installed, the blade part number or word bottom will face the ground.

Step Seven

Reinstall the mower deck by following the procedures in reverse order. Carefully slide the mower deck underneath your mowing machine after flipping it over.

Step Eight

Reattach your mower deck. Slide the pins of the deck to their right position and re-connect your cotter pins.

Step Nine

Reinstall your mower belt. Put your belt in position according to the routing diagram. Make use of a 9/16-inch socket to release the tension and finish routing the belt.

Step Ten

Ensure that you reconnect your spark plug cables. 

2. Worn Out Blade Spindle Bearings

Worn-out blade spindle bearings can be a reason why your Cub Cadet riding mower may lose power when blades are engaged. 

The bearings enable the blades to freely spin on their axis. If it is worn out, it can cause friction and may make your mowing machine lose power. Learn about some top-rated grits for sharpening lawn mower blades.


  • Examine if the blades can freely spin on their axis. If not, it means that the bearings in the blade spindles are worn out.


  • Replace worn-out blade spindle bearings.

3. Blocked Muffler

The muffler of your Craftsman riding mower is responsible for reducing exhaust noise and also preventing exhaust sparks from igniting dry grass.

When it gets clogged by dirt, fluid, grass and other debris, it can cause your Cub Cadet mowing machine to lose power.


  • Inspect your muffler for dirt, grass, fluid and other debris
  • If you notice a colored smoke that emits from your Cub Cadet riding mower, it might indicate that the muffler is clogged.


  • Ensure that you change the blocked muffler. 

4. Clogged Fuel Filter/Fuel Lines on The Cub Cadet riding mower

Dirt and substances left behind by running old gas can cause the fuel filter and fuel lines to become blocked. This can cause fuel restriction and make the mower lose power.


  • Check the fuel filter for clogs. If you notice that enough gas isn’t passing through the fuel filter or it is not enough to run at full throttle, it indicates that the fuel filter needs a replacement
  • Inspect for clogs in the fuel lines by starting and stopping the fuel flow, using the fuel shut-off valve situated on the bottom of the fuel tank.
  • Take off the furthest end of the fuel line (just one section) and place it in the container.
  • You can also check other sections of the fuel line for clogs. If the line is cracked or dry, you may need to replace it with a new fuel line.


  • Replace the fuel filter if it is in bad condition.
  • To fix clogged fuel lines, remove the section of the line and spray a carburetor cleaner into the line to help loosen the clogs.
  • Blow compressed air through the line to eliminate obstructions.
  • Replace the fuel line if it is dry or cracked.

5. Bad Gas

Bad gas in your Cub Cadet lawn mower can cause it to lose power while the blades are engaged. 

Using a gas that contains ethanol is not ideal for your Cub Cadet lawn mower because it  attracts moisture in the fuel system 

To protect your Cub Cadet mowing machine from the effects of ethanol, you need to use your gas within 30 days.

Furthermore, you can add a gas additive to the gas system to stabilize the gas against the buildup of moisture and ethanol separation.


  • Check the fuel system for bad gas. If you notice that the gas that is left in the tank is more than 30 days in the tank, you need to drain the fuel tank.


  • Drain your gas tank by removing the gas and placing it in a container for recycling. Flush your gas tank and fill it with fresh gas treated with a fuel stabilizer. 

6. Dirty Carburetor


This is another reason why your Cub Cadet mowing machine may lose power while the blades are engaged. 

The deposits that are left behind by bad gas can clog your carburetor and stop the regulation of the air and gas mixture.


  • Check your carburetor for the buildup of deposits and clean it.


  • Clean the carburetor or replace it if it is bad. 

7. Dirty Underside

A dirty underside might be one of the reasons why your Cub Cadet riding mower may lose power when the blades are engaged.

Whenever the blade is engaged, the underside rotates on a crankshaft to mow the grass. The mower engine can shut off if there is an interference in this rotation.


  • Inspect the connection of the crankshaft to see if it rotates freely. If the crankshaft’s connection does not rotate freely, it indicates that the mower’s underside is dirty.


  • Clean the blade so that it will be free of debris, dirt and grass. 

8. Worn or Loose Cub Cadet Mower Belt

When your Cub Cadet mower belt is not properly routed, it can make the mower lose power when the mower blades are engaged.

It can also cause lose of power if the belts  are worn. Furthermore, a loose Cub Cadet mower belt can also fall off your pulleys, causing your mower to lose power.


  • Check your Cub Cadet belt for cracks, breaks, slippage or wear.


  • Replace the belt if it is not in a good condition.

9. Improper Valve Adjustment

Problems may arise from the engine as a result of improper valve adjustment.  

If the engine of your Cub Cadet mower comes with valves and the mower is losing power, you can check if the valves are properly adjusted.


  • Check the valves if it is properly adjusted.


  • Ensure that you properly adjust the valves or you seek the help of an expert to help you out.

10. Bad Pulleys

The mower belt drives the pulleys, which in turn moves spindles. 

If the pulleys cannot turn freely, they would cause the engine to lose power. This will affect the operation of your Cub Cadet riding mower.


  • Check pulleys if they are moving freely. If not, it indicates that the pulleys are bad.


  • Replace the pulley if it is sticky or damaged.

11. Dirty Air Filter

It is also important to check the air filter if your Cub Cadet riding mower is losing power when the blades are engaged. 

The mower engine requires air to run and when it no longer gets the air it requires, the engine may lose power.


  • Take off the air filter from the air filter housing and check for dirt on it


  • Clean or replace the air filter if it is in bad condition.

12. Faulty Spark Plug

For air and gas to be ignited, the mower’s spark plug must be in a good condition and correctly adjusted.

Over time, it may wear out and it will no longer have enough power to ignite gas and air This can make the riding mower lose power when blades are engaged..


  • Use a socket wrench to remove the spark plug.
  • Clean the spark plug with a wire brush.
  • If the firing end is covered with carbon, it means that the spark plug needs to be changed.


  • Replace the faulty spark plug with a new one.


It is important to note that this is one of the most common Cub cadet mower problems.The reason your Cub Cadet mower loses power when blades are engaged could be a defective spark plug, a worn or loose belt, a dirty underside and a dirty carburetor.

Read our recommended fixes to identify and solve these problems. If the problem persists after implementing the tips shared here, it is advisable to seek the help of an expert to handle the issue.