Troubleshooting 4 Common John Deere L120 Problems (Professionally)

As a John Deere L120 owner, you know that it is an excellent lawn and garden tractor. However, like any other machine, it can break down or have problems from time to time. In this post, we will go through the 4 most common John Deere L120 problems and provide solutions that we’ve seem, and how to fix them. From starting trouble to transaxle problems, worn-out hydro pumps, and smoke production, we have got you covered with all the information you need.

We will also answer other common questions users have about their John Deere L120s, including what other users are saying about them and what the costs are to repair these tractors. We (and Chris from the team also) have experience with and have run the L120 for many hundreds of hours and can speak from experience on its problems and how we’ve solved them. Additionally, we will provide tips on maintenance steps that should be taken to avoid problems and keep your John Deere L120 running smoothly.

Also Read: John Deere Lawn Tractor Series and Individual Models

john deere l120 with problems tractor on green lawn

Common John Deere L120 Problems

First, to troubleshoot these problems, you need to identify their root cause and take appropriate steps accordingly. You may need to replace parts such as spark plugs, fuel lines, or even the fuel filter to fix some of these problems. Proper maintenance of your mower’s blade and deck is essential too. Briggs & Stratton is one of the most trusted brands for small engines that are commonly used in lawn tractors like John Deere L120.

If you encounter vibration while cutting your lawn with this model, it could be due to an unbalanced blade or worn-out sheaves in the clutch system. Also, air filter replacement should be done regularly for optimal performance.

With proper maintenance and care of your John Deere L120 tractor and by following simple troubleshooting tips when encountering any issue during its operation, you can keep it running smoothly for years to come.

1. Starting Trouble

If you are experiencing starting trouble with your John Deere L120 lawn tractor, you are not alone. This is a common problem that can be caused by various issues like a faulty ignition switch, dead battery, or clogged fuel filter. To troubleshoot this problem effectively, you need to start by checking the battery and ensuring that it’s fully charged. If that doesn’t work out for you, try cleaning or replacing the fuel filter. Keep in mind that the ignition switch may also need to be replaced if it’s not functioning properly.

Additionally, make sure that all other aspects of your mower are in excellent working condition before troubleshooting starting trouble. Check for loose spark plugs or carburetor and fuel lines as these may cause running issues leading to starting trouble in your lawn tractor.

2. Transaxle Problems

John Deere L120 tractors may experience trouble with their transaxles that can lead to shifting difficulties, decreased speed and power or whining noise. A reduction in speed can cause problems with cutting grass effectively which defeats the purpose of owning a mower. Transaxle issues can be due to a variety of causes like worn-out axles or gears, low fluid levels, and defective pumps or motors among other reasons.

It is crucial to address any signs of these symptoms promptly before they develop into severe damage. To fix this common John Deere L120 problem, you should ensure that there is enough fluid in the transaxle system after checking its levels first. If adding fluid does not solve the issue, replacing the entire transaxle should be considered.

Routine checks for wear and tear on all parts of your mower are essential for preventing any occurrence of transaxle faults. Regular maintenance recommended by John Deere such as oil and filter changes, as well as inspections of all parts of the mower, including the blades, mower deck, spark plug, fuel lines, diesel or carburetor should be followed to avoid any John Deere L120 problems.

3. Worn-out Hydro Pump

The hydro pump is a crucial component responsible for powering the transmission of your John Deere lawn tractor. Over time, the hydro pump may wear out due to constant use. This leads to power loss and difficulty in steering your john deere tractor as efficiently as before. To avoid such problems with your John Deere L120 mower or any jd mower model, regular maintenance should be performed on the hydrostatic transmission and other parts such as fuel lines, spark plugs, fuel filters, air filters, and fuel pumps.

It’s essential always to keep up with the regular maintenance schedule outlined in your John Deere L120 manual or other john deere manuals for different models of john deere tractors. However, if you suspect an issue with your hydrostatic transmission leading to power loss or steering difficulty even after performing regular maintenance on the mower’s blade and other parts such as briggs and stratton engines, cylinder heads, clutches, and carburetors among others; it’s best to have it checked by a certified technician.

Hydrostatic transmission problems are common in all types of lawn mowers including backhoe tractors. Therefore it’s advisable not to ignore any unusual vibrations or sheave noises coming from your mower deck or transaxle. Incorporating throttle valves, diesel engines, and pulleys to ensure that the hydro pump works smoothly will go a long way in preventing hydro pump issues from arising.

4. Smoke Production

Owners of John Deere L120 lawn tractors often face the issue of smoke production, which can be caused by various factors such as oil leaks or clogged air filters. Regular maintenance and cleaning are important to prevent smoke production and other problems with your John Deere L120 tractor. It is recommended to inspect the engine regularly for any visible signs of damage, leaks, or wear and tear. In addition, checking the air filter frequently to ensure it’s clean and replacing it if necessary will help reduce smoke emissions. Moreover, using the right type and grade of oil for your engine can make a significant difference in preventing smoke formation.

To avoid any problems with your John Deere L120, it’s best to follow the manufacturer’s recommended maintenance schedule. Regularly checking fuel lines, spark plugs, fuel filters, air filters, fuel pumps, throttle valves, cylinder head gaskets, and mower deck belt tensioner sheaves for wear and tear will also help maintain optimum performance. Several secondary key terms related to John Deere L120 problems such as hydrostatic transmission problems, cutting ability, and PTO clutch engagement issues could also arise if maintenance isn’t done regularly.

It’s essential to get professional help if a complex issue arises like transmission problems or worn-out hydro pumps that require replacement or repair to avoid more significant problems. Owning a John Deere L120 shouldn’t be a nightmare if proper maintenance and care are taken.

Other Common Questions and Answers

What are the most common problems with the John Deere L120?

The most common problems with the John Deere L120 are engine problems, electrical problems, transmission problems, mower deck problems, and steering problems.

How can I diagnose a misfire in the John Deere L120 engine?

To diagnose a misfire in the John Deere L120 engine, you will need a spark plug tester and a timing light. First, remove the spark plugs and test them with the spark plug tester. If the spark plugs are not firing properly, replace them. Next, check the timing of the engine with the timing light. If the timing is incorrect, adjust it.

How can I fix a blown fuse in the John Deere L120?

To fix a blown fuse in the John Deere L120, you will need to identify the fuse that has blown and replace it. The fuse box is located under the hood of the tractor. The blown fuse will be labeled with the amperage rating of the fuse.

How can I troubleshoot a difficult-to-shift transmission in the John Deere L120?

To troubleshoot a difficult-to-shift transmission in the John Deere L120, you will need to check the fluid level and condition of the transmission fluid. If the fluid level is low or the fluid is dirty, replace the fluid. Next, check the operation of the shift linkage. If the shift linkage is not operating properly, adjust or replace it.

How can I sharpen the blades on the John Deere L120 mower deck?

To sharpen the blades on the John Deere L120 mower deck, you will need a lawn mower blade sharpener. The blades should be sharpened every 25 hours of mowing.

How can I fix a wobbly steering wheel on the John Deere L120?

To fix a wobbly steering wheel on the John Deere L120, you will need to check the condition of the steering linkage. If the steering linkage is loose or damaged, tighten or replace it.

What are Other Users saying about the John Deere L120?

The John Deere L120 has received mixed reviews from users. While some have experienced problems with the transmission and engine, others have praised its durability and reliability. It is advisable to read multiple reviews and conduct thorough research before making a purchase decision.

Some of the main complaints users are reporting about the John Deere L120 include engine issues such as not starting, electrical issues such as the starter not working properly, machine problems such as unusual noises and vibrations, and mower issues. Another issue that has been reported is overheating after running for about 20 minutes. These complaints are based on user reviews from various websites such as Amazon, Home Depot, and TractorData.

What are the Costs to Repair these Lawn and Garden Tractors?

Repair costs for a lawn and garden tractor like the John Deere L120 vary based on the issue and damage. Basic tasks like oil changes cost around $30-$50, but complex repairs like engine replacement can run over $1000. Regular maintenance can prevent future expenses. It’s wise to seek professional input for repair cost estimates. If you are experiencing problems with your lawn and garden tractor, it is always best to consult with a professional mechanic to get an accurate estimate of the repair costs.

In addition to the cost of repairs, it is also important to consider the cost of regular maintenance. Regular maintenance, such as oil changes and tune-ups, can help to prevent future repairs and extend the life of your lawn and garden tractor. The cost of regular maintenance will vary depending on the make and model of your tractor, but it is typically a small investment that can save you money in the long run.

What are the Most Costly Repairs?

The cost of repairing a John Deere L120 depends on the problem. Basic maintenance is affordable, while significant repairs like engine or transmission replacement can be expensive, several thousand Dollars typically. I’ve installed a used engine before, but I’d advise against doing so. Do it right the first time! It’s wise to obtain an estimate from a reliable mechanic before committing to any repairs.

What are Some Cheap and Simple Repairs?

The cost of repairing John Deere L120 problems can vary and minor repairs like belt or spark plug replacement can be done for under $100. Regular oil changes and air filter replacements are also inexpensive and easy to do yourself. However, it’s important to make sure you have the necessary tools and knowledge before attempting any repairs on your own. Always consult with a professional if you are unsure about a repair or maintenance task. Taking care of minor repairs and regular maintenance can prevent bigger issues down the road and save you money in the long run. It is important to be aware of the potential problems that can arise with your John Deere L120 lawn and garden tractor. While some repairs can be costly, others may be affordable and simple to fix.

Regular maintenance is crucial in preventing these problems and extending the life of your tractor. Remember to consult with a professional mechanic before committing to any repairs and always seek guidance if you are unsure about a repair or maintenance task.

What is the warranty on the John Deere L120?

The John Deere L120 comes with varying warranties depending on the model and year. Typically, residential lawn tractors have a 2-year/120-hour bumper-to-bumper warranty, with extended coverage available for purchase. It’s crucial to review the warranty details for your specific L120 model. Knowing the details of your John Deere L120 warranty is important in case any issues arise.

If your tractor is still under warranty, make sure to take advantage of any repairs or replacements covered by the manufacturer. It’s also important to follow the recommended maintenance schedule outlined in your owner’s manual to keep your tractor running smoothly and avoid voiding your warranty. If you are unsure about any aspect of your warranty, contact your local John Deere dealer for assistance.

What Maintenance Steps Should be Taken to Avoid Problems with a John Deere L120?

To avoid problems with a John Deere L120, follow the manufacturer’s recommended maintenance schedule, regularly check and change the oil, keep the air filter clean, and check tire pressure. These steps help prevent engine damage and improve overall performance for optimal handling. Additionally, it’s important to keep the tractor clean and dry when not in use, as moisture can cause corrosion and damage. Always check for any loose or broken parts before operating the tractor to avoid accidents. Finally, make sure to store your John Deere L120 in a safe and secure location, protected from harsh weather conditions that could cause damage. By following these maintenance steps, you can extend the life of your John Deere L120 and avoid many common problems.


In conclusion, the John Deere L120 is a reliable garden tractor with some common problems that can be easily fixed with the right tools and knowledge. From starting trouble to worn-out hydro pumps, and smoke production to transaxle problems, we’ve covered it all.

It’s always helpful to know what other users are saying about this machine, the costs of repair, and the warranty you get when buying one. A regular maintenance routine can also help avoid any potential problems in the future. If you’re facing transmission problems with your John Deere L120, we’ve got tips and tricks to help you fix them. Check out our related posts and FAQs for more information on how to keep your garden tractor running smoothly.

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