Kubota GR2120 Problems: What Every Owner Should Know

Several months ago, I was in the market for a new lawn tractor. After doing extensive research, I decided to go with the Kubota GR2120 because I had heard many great things about it. Little did I know that this machine was going to test my patience and technical skills!

As I had purchased a previously owned machine, it didn’t come as a shock when I quickly encountered some issues. But don’t get me wrong! The Kubota GR2120 is a great lawn tractor, and I’m still very pleased with my purchase.

I just want to share some of the problems that I encountered, and how I solved them in case it helps someone else out there.

Engine is overheating

Since I bought my Kubota GR2120 after an initial inspection, the engine start-up problem was not the first problem I faced. In the first few weeks, it was running great, but then the engine started to overheat. After doing some research and asking a few people, I concluded that the cooling system was blocked and there was a lack of air circulation due to a clogged air filter.

Luckily, I had some extra time on my hands, so I decided to tackle this problem myself. I replaced the air filters and changed out the coolant, which seemed to do the trick.

However, during my research, I found several possible causes for engine overheating, such as a damaged fan belt, low coolant levels, or even a damaged thermostat.

If you are experiencing problems with your Kubota GR2120 engine running hot, here’s what you should do:

Check the Coolant LevelThe first step in diagnosing an overheating engine on the Kubota GR2120 tractor is to check the level of coolant in the radiator. Low levels of coolant can cause overheating due to inadequate cooling. Make sure that there is enough coolant in the reservoir, and top up if necessary.


Check for LeaksIf there is an insufficient level of coolant, you should investigate to determine where it is leaking from. Look out for leaks at or near the radiator or hoses connecting to it, which could be a sign of a cracked component or loose connection somewhere in the cooling system.


Inspect Fan Belt TensionIf all components look secure, check that the fan belt tension is sufficient by using a fan belt tension gauge. Ensure that it is tight enough so that it does not slip when engaged but not too tight, as this can damage other components in the engine, such as crankshaft bearings and water pumps, over time.


Flush Cooling SystemIf all other items seem to be functioning correctly, then flushing out the cooling system can be beneficial as sitting antifreeze and contaminants will build up over time, creating deposits and blockages which reduce efficiency and cause overheating issues.

It’s a good idea to flush out your cooling system at least once every year or two, depending on usage levels – consider doing this before any problem arises with overheating, as this will help prevent future issues occurring due to debris clogging up parts of your engine’s cooling system.


Replace ThermostatA faulty thermostat may also be causing problems with your Kubota GR2120 tractor’s overheating issue; inspect yours for any signs of corrosion or damage and replace if needed, as a faulty thermostat can restrict coolant flow resulting in an overly warm engine temperature under load conditions – especially during warmer months when temperatures are higher outside too!

The engine is difficult to start.

After some time of use, the engine of your Kubota GR2120 Garden Tractor may become difficult to start. This is the second problem I faced with my Kubota GR2120 tractor. Fortunately, this was fairly easy to diagnose and fix, as it turned out that the fuel filter was clogged. Replacing the filter resolved this issue for me.

Besides the issue with the fuel filter, however, there can be other causes for a hard-to-start engine. Here are some common problems that can cause an engine to be difficult to start, as well as steps you can take to troubleshoot them:


Closed Fuel Supply ValveThis valve prevents fuel from entering the engine, so it must be open for the engine to run. Check if yours is closed and open it if necessary.


Water, Dirt, or Air in Fuel SystemIf there are any foreign contaminants in your fuel system, they can clog fuel lines and prevent the engine from running properly. Drain, flush, fill and bleed your system regularly to keep it clean and free of any blockages.


Clogged or Damaged InjectorsInjectors deliver fuel into the cylinders of an engine. If they become clogged or damaged, then they won’t be able to provide enough fuel for your engine to run smoothly. To remedy this problem, you need to clean or replace your injectors depending on their condition.


Damaged Fuel Injection PumpThe injection pump pressurizes the fuel before it enters the combustion chamber of the engine, so if this part is damaged, then the engine won’t get enough fuel for it to start up quickly or easily. You will need to repair or replace your injection pump if it is at fault here.


Poor Engine CompressionLow compression in an engine’s cylinders means that not enough pressure is being built up when air and fuel are combined together during combustion, which makes starting difficult or impossible in some cases. Inspecting your cylinder block and replacing any defective components should help you solve this issue with relative ease!

Engine Stops Suddenly During Operation

The worst nightmare of all Kubota GR2120 owners is that their engine just suddenly stops in the middle of a job, which my neighbor who owns the same model as mine had to, unfortunately, experience once. If this has happened to you, it is likely that a fuel filter clogged up with dirt or other debris is the culprit here. Replacing his fuel filter was not only affordable but also solved the problem.

But that’s not the only cause. As I scraped through forums and other related sites, I found several causes for this problem. And guess what? I found some solutions as well.


Engine Has Not Warmed Up To the Required TemperatureIf your Kubota GR2120 has not warmed up to its proper temperature, it can stop running abruptly. You should check the thermostat and warm up the engine until it reaches its proper temperature.


Air In The Fuel SystemIf there is air in the fuel system, it can prevent your engine from running properly or cause it to stop suddenly without warning. To fix this issue, you should bleed the fuel system by removing any air trapped in it and replacing it with fresh fuel.


Irregular Fuel InjectionIrregular fuel injection timing can affect the performance of your Kubota GR2120’s engine and cause it to cut off abruptly during operation. If this is happening, check that all the spark plugs are firing at their correct intervals and adjust the timing if necessary for optimal performance.


Dirty Fuel Filter ElementA dirty filter element can restrict fuel flow from reaching your engine, which can result in it stopping suddenly while in use. To fix this problem, service or replace your fuel filter as needed to ensure proper fuel flow through your engine’s system.


Clogged Or Damaged InjectorsIf one or more injectors in your Kubota GR2120’s fuel system are clogged or damaged, this could be causing inconsistent pressure within the system, which can lead to sudden stoppage of the engine during operation.

To optimize Kubota GR2120’s engine during operation and eliminate any sudden stops, it is imperative that you inspect all injectors for obstructions or damages. Should they require replacing, make sure to do so right away in order to gain the best performance results.

Smoke produced by the engine

Kubota GR2120 problems

When you’re operating your Kubota GR2120, you may notice some smoke coming from the engine. It happened to me not once but twice, and I knew something was up. After inspecting the engine, it turns out that the air filter wasn’t tightened properly, and some debris had made its way into the engine. I quickly cleaned it out and then tightened the filter, and voila! No more smoke.

It was easy for me to diagnose the problem fast because the color of the smoke was black. If the color of the smoke is bluish-white, engine oil leakage could be the culprit. Luckily, that wasn’t my issue, and I was back to work in no time; if that is your case, you might need to replace the engine oil or gaskets.

Starter does not function.

If you are a heavy worker like me and you have a Kubota GR2120, then you know the importance of a fully functioning starter. It’s no fun when your machine won’t start, and all you hear is a “click, click” sound. My friend who also owns a Kubota GR2120 once had to face this problem. In his case, the solenoid was to blame, and replacing it solved the problem.

However, there are several other causes that could be causing your starter to malfunction. It could be a faulty ignition switch, loose battery cables, or even a corroded battery terminal. Fortunately, there are some troubleshooting steps that you can take to try and get your tractor up and running again. Here is a list of things you should consider if your starter fails to work:


Check the BatteryThe most common cause of a starter motor failing to work is a drained or worn-out battery. Make sure that the battery is connected properly and has enough charge. Recharge or replace the battery if needed.


Check the Wire HarnessThe most common cause of a starter motor failing to work is a drained or worn-out battery. Make sure that the battery is connected properly and has enough charge. Recharge or replace the battery if needed.


Verify Battery CapacityMake sure that your battery still has enough capacity to power the starter motor correctly. If it does not, then you may need to recharge it before attempting to start again.


Inspect Spark PlugA faulty spark plug or one with an incorrect gap can prevent a proper ignition and result in the failure of the starter motor to work correctly. Clean, gap, or replace it as needed to ensure the proper functioning of your engine’s ignition system.


Replace Starter Motor/SolenoidIf all other steps have been completed and your starter still fails to function, then you may have an issue with either the starter motor itself or its solenoid switch. Replacing these components may be necessary in order to get your tractor running again smoothly and reliably.

The Battery Does Not Charge.

After several years of service, the battery in your Kubota GR2120 may no longer charge properly or lose its charge quickly. Since my one was a second-hand purchase, it came with an older battery. However, I was able to easily replace it with a new one, and my Kubota GR2120 has been running great ever since.

If the battery on your machine is not charging, it can lead to a wide range of issues and decreased performance in the long run. Fortunately, troubleshooting this issue can be relatively simple if you know what to look for. Here are some common Kubota GR2120 problems and solutions when it comes to a battery that won’t charge:


Loose or Corroded ConnectionsService or Tighten Connections – The first thing to check is any loose or corroded connections either on the battery itself or from the terminals leading from the battery. Make sure everything is securely connected and tight; you may need a pair of pliers for some of them.


Defective Battery Terminal ClampsChange Terminal Clamps – The terminal clamps are responsible for keeping the connectors attached to the battery posts, so any damage here could cause an electrical issue that would prevent charging. Check all four clamps (two positives and two negatives) and make sure they are in good condition and secure; if not, replace them with new ones.


Defective Battery: Battery Replacement RequiredIn some cases, the problem may lie within the battery itself, which will require a full replacement in order to fix it. You can try testing the voltage with a voltmeter, but if it comes back negative, then you’ll need to purchase a new battery for your Kubota GR2120 tractor(s).


Faulty Alternator/Charging System: Repair or Replace PartsIf all else fails, then you may have an issue with your alternator or other parts of your charging system, such as fuses and relays, which will need to be repaired or replaced by an experienced mechanic in order to get your Kubota GR2120 up-and-running again properly.

Important: No matter what Kubota GR2120 problems or solutions you come across, always keep safety first by wearing protective gear such as gloves and goggles when working around batteries, as they can carry powerful currents even when not charged! For more details on how to diagnose and repair these issues, consult your local professional service center, which can provide further insight into specific components related to your situation so you can get back out there on your machine!

Lawn Mower Leaving Uncut Grass

The main function of your Kubota GR2120 is to cut grass, so when it leaves uncut grass in its wake – that’s obviously a problem. The most common culprits for this issue are either a dull blade or the cutting height not being set correctly. Ensure that the mower deck is set at the correct height for your lawn, and sharpen or replace the blade as necessary.

This can also happen when the cutting deck is clogged – so make sure the grass has somewhere to go!

Uneven Grass Cutting

We use a machine because we want a perfect, even cut every time – but sometimes, uneven cutting can occur on the GR2120. This happened to me several times, and the culprit was different each time. If you are facing the same problem, here are some troubleshooting tips to help resolve the problem:


Check the Tire PressureLow tire pressure is one of the biggest culprits when it comes to uneven grass cutting. Make sure your tires are inflated to their recommended PSI level in order to avoid any problems.


Adjust the Mower Deck LevelThe deck level needs to be adjusted correctly in order for even and consistent grass-cutting to occur. Use a carpenter’s level or an inclinometer to make sure that the mower deck is set up at the correct angle for optimal results.


Sharpen or Replace the BladesDull blades can cause an uneven cut, so make sure they are sharpened regularly according to the manufacturer’s instructions. If they need replacing altogether, you should purchase high-quality blades designed for use with your specific mower model.


Clean Out Any Obstructions from Inside the Mower DeckIt’s not uncommon for objects such as sticks or stones to get stuck inside your mower deck, causing obstructions and resulting in uneven grass cutting. Make sure there isn’t anything clogging up the discharge chute; if there is, remove it before continuing with mowing.


Repair or Replace Any Damaged PartsIf any parts of your mower deck shell have become damaged or broken, then this could also result in an uneven cut due to the misalignment of components inside the deck itself. In this case, either repair any existing damage or replace these parts completely in order to ensure optimal performance.


Check and Replace Mower Spindle As NeededLoose or defective spindles will also cause inconsistencies when it comes to grass cutting; check them regularly and replace them if necessary in order for optimal operation of your machine and even results when it comes time for mowing again!

Trouble shifting the hydrostatic transmission

My friend, who owns the same Kubota GR2120 model, often experiences difficulty shifting the hydrostatic transmission as he works with his machine. He’s not alone in this struggle, as many other owners of this model also find themselves in the same situation.

When you’re having trouble shifting the hydrostatic transmission on your Kubota GR2120, it’s important to diagnose and troubleshoot the problem correctly. Here are some of the most common issues that can cause difficulty shifting:


Stuck or Worn Shift LinkageIf your shift linkage is stuck or worn out, it can prevent you from properly shifting between forward and reverse speeds. In this case, replacing the shift linkage is necessary.


Defective or Stuck Hydrostatic PumpThe hydrostatic pump provides power to the machine and helps drive its motion. If it’s defective or stuck, it can interfere with your ability to shift gears. To fix this issue, you may need to replace or repair the pump.


Unadjusted or Damaged Transmission Shift Control PartsYour Kubota GR2120 has several parts that control how the transmission shifts between gears. If these parts are unadjusted or damaged, they can prevent your machine from shifting correctly and smoothly. In this case, you may need to replace or adjust them as needed.


Low Hydraulic Fluid LevelLow levels of hydraulic fluid in the system can cause problems with shifting as well as other issues related to the performance and operation of your machine. Be sure to check your oil levels regularly and refill when necessary for a smooth-shifting performance from your Kubota GR2120..


Loose Bolts/ConnectionsYour machine’s transmission consists of several different moving parts that must be securely connected together in order for it to work properly. Loose bolts or connections can lead to difficulty shifting gears, so be sure all fasteners are tight before operating your machine.

PTO Problem

As a farmer, I’ve had my fair share of issues with my Power Take-Off (PTO) system. One common problem I’ve encountered is that the PTO doesn’t work or fails. I’ve heard from other farmers that this can happen when the PTO shaft starts to move without enough contact.

Even when I set up my PTO correctly, I’ve noticed that the shafts only partially turn. It’s frustrating to not have all the power I need to run my equipment effectively.

I know that many things can go wrong with a PTO, but the most popular issue I’ve seen is when the Shrub hog stops functioning while the PTO remains unplugged from the power source. This can be especially frustrating if you’re in the middle of a big job and have to stop everything to fix the problem.

  • One of the first things I do when I suspect there may be an issue with my PTO is to check the clutch packs. I’ve found that this is a common point of failure and can cause a variety of problems if they aren’t working properly. I make sure to check them ahead of time to ensure they’re in good working condition and if they’re not, I fix or replace them as soon as possible.
  • If the clutch packs aren’t the problem, I move on to checking the PTO solenoid valve. I test its performance to see if it’s working well and if there are any signs of wear on the control valve’s seal, I replace it. I’ve found that this can be another common issue that can cause problems with the PTO system.

From my own experience, I can say that staying vigilant and regularly checking the PTO system can save a lot of headaches and downtime in the long run.

Final Words – Is Kubota a good brand?

After reading these problems, you might think that this brand is a no-no. But nothing can be further from the truth! Kubota is one of the most trusted names in the industry, and their GR2120 line of Kubota tractors is no exception. So don’t let this list deter you—just make sure to check all bolts and connections regularly, keep up with your maintenance schedule, and you should have no further troubles. Happy Kubota-ing!

If you own a John Deere 737 you should definitely check this guide on John Deere 737 Problems and Fixes Save some money and learn some skills.



Kubota Corporation is a Japanese company that manufactures construction and agricultural equipment, engines, and tractors. Founded in 1890 by Gonshiro Kubota, the company has grown to become one of the leading manufacturers of its products worldwide. Based in Osaka, Japan, Kubota Corporation now operates in over 100 countries with subsidiaries in North America, Europe, and Asia.


The cost of a Kubota GR2120 varies depending on the dealer, condition, and other factors. The Manufacturer’s Suggested Retail Price (MSRP) for the Kubota GR2120 is $10,699. However, used models can be found for as low as $2,100 at auction or up to $14,026 for a new model. Prices may also vary depending on the location and availability of dealerships.


Yes, the Kubota GR2120 is a 4WD mower. It features a 21-horsepower engine and hydrostatic transmission, allowing you to easily maneuver around your lawn. The 4WD system also allows for greater traction and stability when cutting and collecting grass in all conditions. Additionally, the Kubota GR2120 has a 48 in cutting deck and 25-102mm cutting height, making it perfect for both amateur and commercial garden requirements alike.

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