7 Most Common John Deere d140 Tractor Problems

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By Marvin Tucker

Farming Equipment

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John Deere made some of the best high-powered lawn mowers and tractors around. They are known for their modern conveniences, hefty amounts of raw power, and reasonable pricing, making them accessible to those looking to deal with smaller plots of land.

The d140 has seen generally favorable user reviews, with owners praising its ability to mulch the tallest of grass thanks to its competent 22hp engine. As well as the refined ergonomics making for a stress-free user experience and its automatic drive system.

While this sounds like a solid purchasing choice, like most in the John Deere Lawn tractor line, it’s not without issues. If you are considering purchasing the d140, there are some common recurring problems that you should be aware of.

So in today’s article, we’re going to go through what those issues are and how you can fix them, as many of these problems are easily solvable with some good general maintenance.

The most common problems with John Deere d140

While the d140 is generally considered a reliable and robust machine, the reality is these lawn tractors go through a lot and can deal with some rough work.

So while it’s very much a certainty that you’ll run into some issues, many of the problems that you may find cropping up with this machine are easily solvable by yourself without needing to pay hefty repair bills.

Here’s a rundown of all the common issues you’ll have to deal with if you purchase the John Deere d140. And at the end, we’ll give you a verdict on whether this is a worthy investment for your mowing needs or not, taking into account all the common issues it can face.

1. The engine fails to start or struggles to start

Probably the most common point of complaint for users is that, after some time, their engine will start to misbehave. The engine may be difficult to start, noisy when started, or produce unwanted smoke. In some scenarios, it may just not start at all, indicating something more serious.

The first thing to look at is your usage frequency. If your lawn mower spends a lot of time in storage and only sees use during the summer months, the gas in the machine may have become old, outdated, and oxidized. 

This can disrupt the clean flow of fuel to the engine, preventing it from operating at full power – thus resulting in a poorly performing or nonfunctional engine.

So, if your d140 has idled for an extended period, consider discarding the old gas and refilling it with fresh gas.

Similarly, suppose the machine is heavily used with this old/poor gas mix in the engine. In that case, this will also hamper the John Deere lawn mower’s ability to operate at maximum efficiency.

Remember, you must also thoroughly flush out the fuel line before refilling it. Consider using gas with a slightly lower amount of ethanol which some users have reported working incredibly well in this particular machine.

2. Transmission-related problems

Another common issue across the John Deere mower line is that the transmission may develop issues causing the tractor to operate at reduced speeds. This is often triggered by using the mower under too much load. Mainly, lots of uphill or bumpy terrain will contribute to excess stress on the transmission.

Before doing any major repairs, check the obvious things, including the fuel or engine oil levels and ensuring they are adequately topped off.

Next, we must inspect the transmission, particularly its fluid level. Transmission fluid is responsible for helping the gears change smoothly and is vital to the engine’s overall performance.

If the fluid level is too low or dense, it takes more work from the transmission to make the engine function. So if the fluid looks too dark, has poor viscosity (particularly any lumps or what looks like debris), or has a burnt quality, it will need to be replaced. 

Unfortunately, in this scenario, the best solution is to take it to a John Deere dealer to check it, as fixing the transmission can be a demanding process.

3. Problems starting the machine

As vital as the starter is to the machine’s smooth operation, it’s often one of the first things to go. The starter essentially uses a small battery to ignite the engine and get things going. So, if this device breaks or becomes nonfunctional, it will render the entire mower unable to start.

The first step we should take in troubleshooting this is to disconnect the power sources on the mower. This includes the fuel wires, electrical wires, the battery, and finally, the spark plug.

Once this is completed, we can now check the starter. Use a voltmeter to check the voltage on each side of the starter.

  • Turn your voltmeter to the DC setting and connect the wires to the negative and positive sides of the starter.
  • Once both wires are in place, turn the key and see if the tractor starts.
  • Check the display on the voltmeter screen to see if it displayed a current.

If the voltmeter shows no current, your starter may have failed and needs to be replaced.

4. Problems with steering

If your tractor is experiencing issues when it comes to turning, with it feeling stiff and unresponsive, you may also feel excessive vibrations through the steering wheel. It may indicate a problem with the wheels/tires. The most common cause of this is the tire pressure being too low.

In this case, the solution is to ensure your tires have the correct air pressure.

However, in more severe cases, there may be an issue with the support assembly or the steering shaft. These elements will need to be inspected and fixed accordingly based on what is causing the problem.

5. Fuel-related issues

An adequate supply of fuel, using the correct ratio, and good quality fuel are vital to the engine’s smooth operation. So if you find yourself in a scenario where the engine doesn’t seem to be operating at full power, it may indicate a fuel or fuel supply-related issue.

This can often be attributed to blocked or hindered fuel lines or nozzles.

Unfortunately, cleaning out a gummed-up fuel line is not a particularly pleasant task, but it is something that you can do yourself. There are many detailed tutorials around online, from quick and dirty techniques to use from home to how to do it professionally.

Ensuring all your fuel lines are clear is vital. However, you may also notice damage or wear on the fuel line. In particular, you should keep an eye out for any leakages that may represent a split or damage to the line. In this scenario, you should replace the fuel line immediately.

6. Spark plug or electrical issues

Another critical component in the starting of a machine is the spark plug. As the name suggests, this small device generates a small electrical current that manifests as a spark – this spark will ignite the fuel and begin the combustion process, thus starting the engine.

The spark plug needs to be clean for the electrical current to pass through and to be grounded.

But at the same time, spark plugs are cheap and easy to replace as a small DIY project. So we don’t recommend trying too hard to troubleshoot these things. Instead, if you deem the sparkplug to be an issue, ditch it and replace it with a new one.

However, if you want to try and troubleshoot this yourself, you will need to remove it from the engine by wiggling both ends free. Using sandpaper or just a cloth, you can remove any debris or dirt from the sparkplug, as even the tiniest bit can cause the sparkplug to misfire.

If you see corrosion – don’t bother trying to clean it. Just replace it, as it is so inexpensive and widely available.

7. Black smoke is emitted during the operation of the tractor

The sight of black smoke may make you believe some irreparable damage has been done to the engine.

Fortunately, this is not always the case. Usually, this is due to a buildup of dirt, debris, or old funky engine oil being burned off, and we can take a few simple troubleshooting steps to fix this problem.

The first thing to do is clean the air filter, which may have become clogged up with dirt or oil. You can replace these if it looks too old and is beyond treatment. This is usually the better option if it seems exceptionally oily.

You may also find that the throttle is partially engaged, resulting in the continued burning of the fuel while idle. In that case, you should inspect and adjust the choke to ensure it’s fully closed.

The final thing to check is the carburetor’s float level.

John Deere d140 problems: Are they a deal-breaker?

While it may seem like there are a lot of issues that can occur with the John Deere lawn mower, these are issues that you will encounter on pretty much any tractor from the John Deeres range or other manufacturers.

You can circumvent most of these issues with a good maintenance schedule, including a thorough cleaning of the machine. If you keep up with this, it’s a great machine that will serve you well for many years.

However, if you need something a little more robust and your budget can stretch a little further, other higher-end models in the John Deere range may be worth considering.

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