This week’s mowing started out just like every other time until the mower quit. You feel defeated when your Cub Cadet mower shuts off after it got hot. You may be stuck in the middle of your yard during the heat of the day to troubleshoot your problem. You can’t just leave your mower sit in your yard. Grass doesn’t stop growing and you need to get your mower up and running soon.
A Cub Cadet lawn mower may quit when it gets hot because the air filter is plugged, the fuel system is clogged, the oil level is insufficient, the cooling fins are plugged, the spark plug is bad or there is debris buildup under the deck.
I’ve put together a list of the main reasons your Cub Cadet mower engine gets hot and shuts off. Keep reading for the steps to fix your mower problem.
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Reasons That Cause a Cub Cadet to Shut Off When Hot
Plugged Air Filter in Your Cub Cadet
Your Cub Cadet mower requires air to run. When it doesn’t get enough air, your engine can overheat and quit. A plugged air filter full of dirt and debris can restrict air. Replace your air filter annually and clean it several times during your mowing season.
You may have to clean and replace your air filter more often when you mow more frequently than the average homeowner or you are mowing in dusty dry conditions. Cleaning your air filter is a simple task that can keep your mower from getting hot and shutting off. A neglected air filter can contribute to internal engine damage and costly repairs.
FIX: To clean your air filter, carefully remove it from the air filter housing. Don’t allow dirt to enter the air intake. Wipe out any dirt and debris that remains in the housing using a dry cloth. Determine which type of air filter you need and follow the steps to clean it.
Paper Air Filter
- Tap your air filter against a solid surface to loosen the dirt and remove as much as possible.
- Hold your filter up to a light to check for light shining through the paper.
- Replace the filter if you can see light shine through the paper element. Use a new air filter when you cannot see light.
Foam Air Filter
- Wash your filter using a mild dish soap and water to remove the dirt and oil from your filter.
- Rinse until all the soap is removed.
- Lay flat to air dry. Laying out in the sun will help speed up the drying process.
- Once dry, lightly coat your filter using a filter oil. Squeeze out any excess oil from your filter. You do not want your filter dripping of oil. Replace the filter into the housing.
- Do not reuse your foam filter if it is dry, brittle or torn.
Bad or Old Fuel in Your Cub Cadet
Gas that is old can begin to break down and go bad after 30 days. Ethanol and moisture will begin to separate from your fuel causing gummy deposits that can clog your fuel system. These deposits may cause your mower to shut down after running a while. To learn more about the right type of gas and the effects ethanol can have on your Cub Cadet, check out this article.
FIX: Drain your fuel tank using a siphon to remove old fuel from your tank and place it in a gas container. Fill your Cub Cadet with fresh gasoline that contains a fuel additive to stabilizer and clean your fuel system.
I recommend a product called Sea Foam Motor Treatment for your Cub Cadet because it has cleaning agents for the engine and the fuel system. It isn’t only better for the carburetor, it is also good for the valve train as well. Read more about the advantages of using Sea Foam in your fuel system in my article here.
If you still have a clog in your fuel system after changing your fuel and using a fuel system cleaner, check out my article on why a Cub Cadet isn’t getting fuel for other items to check on your mower.
Dirty Carburetor on Your Cub Cadet
A lawn mower carburetor regulates the amount of fuel and air used to create a combustion in the cylinder. When your Cub Cadet has a buildup of gummy and crusty deposits in your carburetor, it may not work correctly causing your mower to shut down after running.
FIX: Remove your air filter and spray carburetor cleaner in the air intake. Start your mower. If your mower starts and then shuts down, it’s time to take apart your carburetor to clean or rebuild it.
If you are a little mechanical and don’t mind working with small parts, you should be able to disassemble and clean your Cub Cadet’s carburetor following the instructions in this guide.
Unsure about tackling the cleaning of your carburetor? Have your local lawn mower repair shop clean it for you. Another option to fix your carburetor issues is purchasing and installing a new carburetor.
Wrong Engine Oil in Your Cub Cadet
It is best to use an air-cooled engine oil that contains a high concentration of zinc. Zinc is an additive used as a cooling agent. This type of oil varies from oil used in cars. A car uses water in a liquid to cool the engine while a lawn mower uses air to cool its small engine.
Most lawn mower small engines manufacturers recommend using an SAE30 or 10W-30 engine oil. You may need to change your oil viscosity to a 20W-50 when operating in higher ambient temperatures. Use this chart along with your owner’s manual as reference to select the correct engine oil for your mower so it doesn’t result in overheating your engine.
FIX: Drain you engine oil using the steps found in my Cub Cadet riding mower maintenance guide. Fill with the fresh oil using the viscosity recommended by the engine manufacturer.
Too Much Oil in Your Cub Cadet’s Engine Crankcase
When there is too much engine oil in your lawn mower, your engine may become hot and shut down. Too much oil causes the crankshaft and rod to have to push through excess oil so they are unable to rotate freely. It can increase crankcase pressure and put internal parts under load causing the engine to quit when it gets hot.
Additionally, the engine may run terribly and shut down when too much oil creates a smoke that clogs the air filter. When the filter is unable to get clean air, your Cub Cadet can shut off while mowing.
FIX: Remove excess oil so you have the correct amount of oil in your Cub Cadet as specified by the engine manufacturer. Remove the spark plug wire and then drain a little oil using one of the following methods:
- Drain Plug: Quickly remove and replace your drain plug to only remove a little oil
- Oil Filter: Remove the oil filter. Have a rag ready to collect a little oil out of the filter.
- Oil Fill Hole: Some push mowers won’t have a drain plug or oil filter. You’ll have to tip over your mower to remove a little oil out of the oil fill hole. Keep the carburetor and air filter on the high side when tilting your mower.
- Oil Extractor Pump: Use an oil evacuator to vacuum out a little oil out of the oil fill area.
- Turkey Baster: Use a turkey baster to suck a little oil out of the oil fill.
Check your engine oil level and add or drain more oil if needed. Once you have corrected the oil level, check and replace your air filter if it has signs of oil on it.
Too Little Oil in Your Cub Cadet’s Engine Crankcase
With an oil level that is lower than the manufacturer’s recommended level, your Cub Cadet can quit when it gets hot. Oil is required to lubricate the internal parts of the engine so they move smoothly. Operating your Cub Cadet with low engine oil causes the oil to heat up and thicken increasing friction in the engine.
FIX: You can attempt changing your engine oil and bringing it to the correct level. However, most of the time, once your mower shuts down due to running on low oil, the simple fix of an oil change will not work. Most likely, you have internal engine damage that requires a small engine mechanic to perform tests to properly identify your engine problem.
Regularly checking your engine oil level is a preventative measure you need to take prior to each mowing. A low engine oil can indicate the engine is burning or using oil. It may also indicate you have an engine oil leak. Read more about this in my article on overheating.
Damaged or Clogged Engine Cooling Fins on Your Cub Cadet
Cleaning your engine cooling fins needs to be completed annually. Debris and dirt can plug up the fan and prevent it from circulating air around your engine block and cylinder to keep it cool. A broken cooling fan fin or clogged fan can be the cause of your Cub Cadet shutting off.
FIX: Remove debris around your cooling fins and replace any broken fins. Remove debris collecting under your engine shrouds and confirm your heat shield is securely in place.
Broke or Dirty Spark Plug on Your Cub Cadet
A dirty spark plug can cause your engine to foul out and stop running. It may have produced enough spark to start your mower, but it may be unable to keep it running. Remove your spark plug and check its condition.
Look for signs of carbon buildup or cracked porcelain. You can attempt to clean your spark plug to remove dirt and reuse. A damaged or excessively dirty dark spark plug must be replaced.
FIX: When the spark plug wire(s) is loose or the gap is not correct, it may cause intermittent running or starting problems. Make sure your spark plug has the correct gap and the wires are securely attached.
Bad Ignition Coil on Your Cub Cadet
When the ignition coil gets hot it can stop working causing your Cub Cadet to shut down. The windings on the coil separate and short out. A faulty ignition coil won’t be able to provide sufficient voltage to the spark plug.
FIX: Use an ohm meter to test your ignition coil to confirm there is no break in the continuity of the coil. Replace when you find a faulty coil.
Bad Cub Cadet Fuel Cap
The Cub Cadet fuel cap is designed with a vent to allow air to pass. Your mower may run for a while and quit when air is prevented to pass through the cap. A vacuum is created in the fuel system causing a fuel restriction. This can result in your mower dying once it has been running for a while.
FIX: Replace your Cub Cadet gas cap if your mower runs while the fuel cap is removed and quits after a short running time with the cap installed.
Clogged Mower Deck & Dull Blades on Your Cub Cadet
Your engine must work harder when you run your Cub Cadet with a clogged mower deck. The engine must turn the mower blades through a bunch of debris with each turn. This causing extra strain put on the engine that can cause it to quit when it gets hot.
In addition to a clogged mower deck, dull mower blades will further add to the problem causing your engine to overload and shut down.
FIX: Sharpen your mower blades and scrape your deck to keep your Cub Cadet’s cut at its best and prevent your mower from being overworked. Avoid mowing your lawn in wet conditions. Wet grass is more prone to collecting under the deck and clumping in your yard.
Need help determining whether to sharpen or replace your blades, check out this article on sharpening Cub Cadet blades.
Other Cub Cadet Lawn Mower Problems & Solutions
The reason your Cub Cadet shuts off after running may not actually be due to overheating your engine. There are other reasons a lawn mower can shut off. Read my article on the most common Cub Cadet problems and their solutions if the items above did not solve your problem.