8 Most Common Kubota GR2120 Problems & Troubleshooting

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By Marvin Tucker

Farming Equipment

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The Kubota Corporation is one of the leading organizations producing engines, construction, and agricultural equipment. Although a Japanese company, these machines are manufactured and distributed in Georgia, America.

The gr2120 is one of the most maneuverable non-zero-turn mowers on the market. Its modest 21hp engine is geared towards large non-commercial use but can also hold its own in smaller commercial applications.

This makes it ideal for those with big lawns or small businesses needing something small, relatively inexpensive, and reliable.

But unfortunately, the gr2120 does suffer from some issues that you, as a prospective buyer, should be aware of.

The most common problems with Kubota gr2120

The gr2120 has many features designed to help improve usability and lower the maintenance required to keep it in tip-top shape.

Kubota’s proprietary low-maintenance shaft drive transmission will stay functional and reliable with minimal upkeep. And the Hydraulic PTO clutch is more reliable, requiring less maintenance and repair than other mowers due to not needing to maintain belts and pulleys.

Kubota should be commended for their efforts to reduce problems and required upkeep, but unfortunately, the gr2120 still does suffer from several issues. So today, we’ll look at those issues and how to fix them. Finally, we’ll share our thoughts on whether this is a worthy purchase despite those problems.

1. The engine struggles to start

The Kubota gr2120’s PTO (Power take-off system) transfers power from the engine to another part of the Kubota tractor by rotating and building up pressure in the hydraulic system.

This is a crucial component for things like raising lifters on tractors, or in the case of the Kubota mower, it will raise the deck and allow you to set your cutting height.

Despite Kubota’s effort to make this system trouble-free and low maintenance, many users have reported that the power take-off system doesn’t seem to rotate and, as such, can’t build up pressure in the hydraulic system.

The first thing to check is the clutch packs to make sure they’re operational and fix as needed. You should also check the PTO control valve to ensure it’s working. If you notice any wear or damage on the control valve, replace it, as these components can break down over time.

2. The engine keeps shutting down

It’s always a troublesome issue when you’re mid-way through your working day, and suddenly the tractor’s engine keeps turning itself off. And while, at first, this can be alarming, it’s more often than not caused by a relatively minor issue that can be self-serviced. 

Let’s look at the primary factors that cause an engine to shut down.

Old or degraded fuel is essential to be mindful of if you store the tractor for long periods, such as during the winter. Over time fuel breaks down and becomes less efficient. And as such, the engine can have difficulty staying running with such poor quality here.

The solution here is to discard the old/broken-down fuel and replace it with new, higher-quality fuel.

The next thing to check is the air filter. This is responsible for removing any dirt or debris that might make its way into the engine. Over time this can become so clogged up that it restricts airflow into the engine, thus throwing off the all-important fuel-to-air ratio.

Often the air filter can be cleaned out, but if it’s already too old and worn, you should replace it.

Next, you should check the fuel lines for deposit buildups that may restrict fuel from reaching the engine. This usually happens due to old fuel building up, so you can use a carburetor cleaner to clear it out.

Finally, the fuel filter should be checked as that old fuel deposit might also clog that up. Clean it out or replace it as necessary.

3. Smoke produced from the engine

Some amount of smoke produced from the engine is not uncommon, and even though you may still be able to use the lawn mower, it will keep like it’s performing okay. Any consistent production of smoke should be checked as, over time, it can adversely affect the lawn mower.

The smoke produced might be white/blue or black, depending on precisely what’s happening.

White or blue smoke is generally an indication of burning oil. This can be caused by overfilling the oil level, which burns off the excess. A leak that’s causing oil to drop onto a hot component and get burned off. Or a blown part such as a head gasket, worn cylinder rings, or using a poor grade of oil might burn off unnecessarily.

All of these areas should be checked to fix the white smoke issue as soon as possible as it’s not good to breathe it in, and it can irritate the eyes.

But what about black smoke? This generally indicates that your engine is receiving too much fuel and has an imbalance fuel-to-air ratio. We also call this ‘running rich.’

The most common cause of this is a clogged air filter which reduces the amount of air making its way to the engine. Clean or replace as needed. You may also need to adjust the carburetor to increase airflow.

In addition, you may wish to consider using a fuel stabilizer which will help keep the fuel fresh for longer and often prevent an excess of fuel from making its way into the engine.

4. The engine is overheating

If your engine is running hot and overheating, it can accelerate component wear, so you should address this as soon as possible. It’s usually a simple issue to keep up with basic repair and maintenance procedures.

  • Check the engine has enough oil. A low oil level can increase engine friction producing more heat. Top up the oil level to make sure everything is lubricated.
  • Clean and unblock the cooling fins. These are responsible for allowing heat to dissipate from the engine, but over time they can become blocked by dirt, debris, and grass picked up from mowing. Give these a good clean.
  • Check the fuel and air systems for blockage or restricted airflow paths, as this will reduce the mower’s ability to dissipate heat due to lack of air. It can also cause unwanted pressure within the system. Remove any blockages and clean thoroughly.

One thing you should also be mindful of as an end user is how hard you are making the Kubota tractor work. Trying to cut wet or exceptionally thick grass or moving over uneven terrain at high speeds puts strain on the lawn tractor. If the tractor is overheating due to an excessive workload, try to slow down a bit.

5. The starter doesn’t work

This is a relatively common problem you will run into on many mowers, but fortunately, it is pretty easy to fix.

The primary cause of the starter not working is the battery. So the first thing to do is check that the battery is adequately charged, mainly if it’s been in storage for some time, as it will drain itself.

Next, check all the connections and ensure nothing has come loose. Keep an eye out for corroded connections.

If the battery is charged and seems to work yet dies pretty soon after, it’s an indication that the battery is now old and needs to be replaced.

6. Poor tractor handling

Operational and steering issues are an unfortunate thing you will likely run into at some point as a Kubota gr2120 owner. Sometimes this is caused by something relatively simple and user-serviceable. But it may also be more complicated and need to be checked by a qualified repairman.

The main thing you can check as the operator is the transmission oil. This is a vital part of the performance and operation of the steering system. So make sure to keep that topped up.

You should also check there is equal tire pressure between all tires. If one is even slightly flat, it will make the lawn tractor lean down on that corner and become more challenging to control.

7. Issues with the transmission

The transmission uses a hydraulic motor to transfer power to a mechanical drive chain, allowing the tractor to move.

So, generally speaking, if you are having a transmission issue, it can be pinned back to the hydraulic system.

Sometimes air can make its way into the system, reducing the amount of hydraulic pressure. In this scenario, you should bleed the hydraulic system to ensure no air. You should also check all the hydraulic lines and connection points to ensure no breaches that might allow air to enter.

Finally, you should ensure the hydraulic oil level is sufficiently topped up.

It’s also worth checking the brakes as sometimes this may produce symptoms that look like a transmission issue. If the brakes look rugged or damaged, you should take them in for repairs/replacement.

8. The engine will not idle

Working around an engine that will not idle can be very troublesome. Fortunately, the solution is often straightforward and can be traced back to the fuel filter.

Once again, this can become blogged and clogged, so it should be cleaned and replaced accordingly, ideally every 3 to 4 months, to keep the engine in solid working order.

Kubota gr2120 problems: Are they a deal-breaker?

For non-commercial purposes, having a high-maintenance and problem-laden garden tractor can be very unappealing. And while at first glance it might seem the gr2120 has a lot of issues, they are, in fact, extremely reliable.

You will need to keep up with general maintenance on the Kubota tractor, but it’s all relatively easy to do and doesn’t require any specialized skills or equipment.

Kubota is a well-respected brand that produces reliable and trustworthy garden tractors, so for that reason, we highly recommend the Kubota gr2120 for small format commercial applications and larger non-commercial plots of land.

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