While mowing can be a nice stress reliever after a hard day of work, it gets very frustrating when your zero turn gets hot and quits. A dead mower in the middle of your yard can quickly turn your day upside down.
A zero turn lawn mower may get hot and quit from an air or fuel restriction; insufficient engine oil level; bad spark plug or coil; or a plugged mower deck. Using the wrong engine oil or old fuel in your zero turn can also cause it to shut off.
I have put together a list of items to check out if your mower shuts down after it gets hot. Before you begin troubleshooting, take safety precautions to prevent your mower from starting and moving while working on your zero turn including removing the spark plug boots. Take caution when working around hot and sharp objects on your mower.
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11 Reasons Your Zero Turn Mower Quits When Hot
Plugged Air Filter on Your Zero Turn Mower
The air filter is essential to ensure your zero turn mower is getting clean air. It prevents dirt from entering the air intake resulting in damage to the engine. The air filter should be replaced annually and cleaned several times throughout the mowing season.
When routine air filter maintenance is skipped, your filter can become plugged restricting air flow to the engine. Without sufficient air flow, your engine can get hot and shut down.
Solution: To protect your zero turn mower engine from the negative impacts dirt can have on your engine, you not only need to always use an air filter, you must keep it clean.
Follow these steps to clean a paper air filter element on your zero turn:
- Remove the air filter from the housing. If any dirt remains in the housing, wipe it out with a clean dry cloth. Be careful not to allow dirt to fall into the air intake.
- Tap your air filter element against a solid surface to loosen and remove the dirt from your filter. Never use compressed air as this can damage the filter.
- Hold your filter up to a light source to check for light shining through the paper.
- Replace the air filter if you can’t see light shining through the paper.
- Do not reuse the filter if you can’t see light. You must purchase a new air filter.
- Reinstall the filter into the air filter housing and reinstall the cover.
Bad or Old Fuel in Your Zero Turn Mower
Old gasoline can cause several different problems for your zero turn mower. Most gasolines on the market today contain ethanol. Ethanol attracts moisture that can leave behind a gummy solution causing fuel restrictions that will cause your lawn mower to quit.
Ethanol is corrosive and, after time, will make your fuel components degrade and fail. The water and ethanol mixture will eventually separate from the gasoline and sink to the bottom of the tank after it ages. When it runs through your zero turn, it will cause your engine to run hot and quit.
A diesel-powered zero turn can also run into problems with diesel fuel restricting fuel flow to the engine. Diesel fuel that has been sitting for long periods of time will form solids and condensation in the tank. This can clog your fuel system components. Old diesel fuel will have a dark appearance.
Solution: If you are running old fuel, drain your fuel tank into an approved fuel storage container using a siphon. Fill your zero turn mower with fresh fuel. Use a fuel additive to stabilizer your fuel, reduce moisture and clean the fuel system. I use a safe petroleum-based product called Sea Foam Motor Treatment. Find more information about the advantages of using Sea Foam here.
Dirty Carburetor on Your Zero Turn Mower
Your zero turn mower’s carburetor regulates the amount of fuel that is mixed with air to start a combustion in your engine. Without the carburetor working properly, your engine may not get the right amount of fuel causing your mower to shut down.
Before you jump to the conclusion the carburetor is to blame for your fuel restriction, make sure you have fuel flowing to the carburetor. Check out this article for all the items that can prevent your zero turn from getting fuel.
Once you have confirmed you are getting fuel to the carburetor, remove the air filter and spray carburetor cleaner into the air intake. Start your mower. If it starts up, runs and then dies, it is likely you have a problem in your carburetor.
Solution: Dissemble and clean your carburetor using the instructions in this guide. Not feeling up to the task? Have your local lawn mower repair shop clean your carburetor or purchase and install a new carburetor.
Wrong Type of Engine Oil in Your Zero Turn Mower
The best kind of fuel to run through a gas-powered engine on your zero turn is an air-cooled engine oil. This type of engine oil contains a high concentration of zinc that is used as a cooling agent. The cooling system on a mower differs from that on a car. A mower uses air to cool the engine while a car uses liquid to cool its engine.
Most lawn mower small engine manufacturers recommend using an SAE30 or 10W-30 engine oil. While this is the recommendation and good for most areas, you may have to change to a using a different viscosity, like 20W-50 when operating in higher ambient temperatures.
Use this chart provided by Kawasaki Motors along with your operator’s manual to select the correct engine oil for your zero turn mower. Running the wrong engine oil can result in overheating your engine causing it to shut off.
Solution: Replace the oil with the correct oil viscosity for your mower and ambient temperature. You may need to consult with a small engine mechanic if you continue to experience problems after changing to the correct oil.
Low Engine Oil Level in Your Zero Turn Mower
You never want to be in a situation where you are running your zero turn with a low engine level. It’s necessary to check your engine oil before each mowing to ensure it is at the correct level. If you find you have a low oil level, identify the reason why your engine oil level is low and fix it. This could be due to an oil leak or from your engine burning or consuming oil.
Not having enough engine oil in the crankcase will fail to provide your internal engine components with sufficient lubrication. Increased friction and heat will build in the engine because of the lack of lubrication. This can cause the zero turn to overheat and smoke; burn oil; and melt engine parts.
Solution: Add engine oil to your mower to bring it to the right level as indicated on the oil fill dipstick. This may solve your problem. Chances are, if the engine got very hot because of a lack of oil, you have caused engine damage that will have to be diagnosed and repaired or replaced by a small engine mechanic.
Too Much Engine Oil in Your Zero Turn Mower
While most people know a low engine oil level is bad for an engine, they don’t always realize too much oil is also bad. Overfilling your zero turn with engine oil will make the crankshaft and rod move through the excess oil so the parts are not able to move freely. Pressure in the crankcase can build putting your engine under load causing it to get hot and quit.
Too much oil can also cause your engine to smoke. This smoke can plug your filter causing the engine to overheat and die because of the air restriction.
Solution: Remove excess engine oil by draining a little oil through the drain plug of engine oil filter. You can also use an oil evacuator or turkey baster to suction a little oil from the oil fill area. Use the oil dipstick to check the oil level. Continue to drain or add oil until your oil level registers between the fill lines on the dipstick.
If you still experience problems after correcting the engine oil level, check out my article on too much engine oil in your lawn mower for more information.
Damaged or Plugged Engine Oil Cooling Fins on Your Zero Turn Mower
Cooling fins are used on your zero turn to circulate air to keep the engine block and cylinder cool. When they become plugged or damaged, the fins fail to push air and can cause your engine to overheat and quit.
Solution: Remove dirt and debris that has collected in your fins. Repair any damaged fins. Clean around the engine and engine shroud. Make sure your heat shield is securely in place.
Bad Spark Plug in Your Zero Turn Mower
A dirty or damage spark plug can foul and fail to provide the spark needed to keep the engine running. A plug that isn’t gapped correctly or one where the spark plug wires are loose can also cause the mower to quit.
Solution: Remove your spark plug(s) and check for signs of buildup on the tip. Clean the plug or replace it if the tips are dark in color. Inspect the plug for a broke porcelain or burnt filament. Ensure your plug is gapped to the manufacturer’s specification and the spark plug wires are secure.
Bad Ignition Coil on Your Zero Turn Mower
When the coil gets hot, it can stop working causing your zero turn mower to quit running. The windings on the coil can separate and short out. A bad ignition coil will not be able to provide sufficient voltage to the spark plug.
Solution: Check for a break in the coil’s continuity using an ohm meter. If you find a break, you must replace the mower.
Clogged Fuel Cap on Your Zero Turn Mower
The fuel cap is designed to vent. When it no longer vents and allows air to pass through the cap, the fuel tank can act like a vacuum and prevent gas from flowing out of the fuel tank. This will cause your mower to quit.
Try to isolate the problem by running your mower with and without your fuel cap. If it starts and runs fine without the fuel cap, but shuts down after a while once the fuel cap is reinstalled, the fuel cap may be the problem.
Solution: Replace your zero turn mower cap
Plugged Zero Turn Mower Deck & Dull Blades
A zero turn mower deck that is packed full of grass clippings and debris will put an extra strain on your engine. The engine must work hard to rotate the blade through a plugged mower deck. This can cause your mower to get hot and quit. Adding dull blades to a packed deck further magnifies the problem.
Solution: Scrape your zero turn deck to remove the debris and sharpen your mower blades. While you need to regularly scrape the deck and can’t avoid grass buildup, you can minimize it by not mowing wet grass. You can also use a silicone or Teflon spray to reduce the amount of grass and dirt that sticks to the deck.
Still Having Problems with Your Zero Turn Mower?
If you have gone through all of the items above to solve your zero turn problem and still haven’t found the solution, check out this handy guide I put together listing common zero turn problems and solutions.