5 Most Common John Deere L120 Problems

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By Marvin Tucker

Farming Equipment

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The John Deere L120 might be one of the most divisive models from the brand. It seems that users either love it or hate it with a passion.

Indeed, this lawn tractor can be your best friend or your worst nightmare. Despite having all the right features to be a long-lasting mower, many problems may arise along the way.

Many complain about starting, running, transmission, hydro pump, and transaxle issues. And these are just the most common ones!

But is the John Deere L120 the worst lawn mower, as some claim? Let’s find out!

The most common problems with John Deere L120

It’s hard to imagine a lawn tractor from John Deere that is so little loved. This brand is the same one that produced great vehicles like the X570, D140, and the budget-friendly 790 tractor.

If you’re looking to buy the L120, you might be confused depending on who you ask for a review. 

Some people will tell you it’s the worst tractor they’ve ever had, and others will proudly affirm that they’ve worked with this model for a decade with little to no issues. The truth, as it often happens, is in the middle. 

Indeed this lawn mower must have some problems that John Deere hopefully will address, but that doesn’t mean that it’s as awful as some users claim. Sometimes it’s just a matter of expertise of the user and a bit of luck.

It’s worth keeping in mind that when you own a lawn mower, some issues are just bound to happen. Every machine gets worn out over time, and it’s up to the owner to practice the necessary maintenance to preserve the mower’s lifespan.

Here’s a comprehensive list of the most common John Deere L120 problems

1. Starting issues

Don’t panic yet, as starting issues are very common with lawn tractors from every brand, including big names like Kubota, Ford, and Bobcat.

If your John Deere lawn mower doesn’t turn over, the problem could be one of the following:

  1. Low/old fuel: either you haven’t kept your fuel level under control, or maybe your mower has been sitting in the garage for more than 30 days. In both cases, you need to refill your tank with fresh fuel.
  2. Faulty battery: you can tell by the way your mower clicks when you try to start it. Use a multimeter to test the battery voltage; anything under 12.7 volts needs recharging or replacing.
  3. Faulty spark plug: these are bound to be changed every 100 hours of work or so, but many people forget or neglect to change them. The spark plug might be the culprit if your engine doesn’t start. Please get a new one and see how it works!
  4. Dirty fuel filter:  this is a classic because even though the filter was designed to keep dirt out of your carburetor, it eventually becomes blocked. There is no need to get them cleaned because they are inexpensive products; replacing them is much more practical.

2. Running issues

If your John Deere L120 loses power while running, the problem is the mower deck, or more specifically, its height.

You should lift the mower deck appropriately if cutting tall or dense grass. Work exclusively on dry surfaces and avoid attempting to cut wet grass.

Also, you might need to go over the same spot twice. If you need to cover a large portion of the land, consider the possibility that your mower deck is getting clogged.

Clean your deck as often as necessary, and don’t forget to sharpen the blades regularly.

Generally speaking, if you practice good maintenance of the mower deck, you should prevent or fix most running issues.

3. Transmission issues

When a lawn mower has motion problems, we tend to think about lack of fuel, battery issues, and similar problems.

While in many cases, safety features could prevent the mower from moving (if the blades are too loose, for example), or maybe the parking brake remained locked, sometimes it’s simply a transmission problem.

Over time, transmissions can frequently cause more than one headache, but most of the time, checking the oil level can resolve the transmission issue.

Your John Deere mower won’t move an inch when the transmission oil level is too low, or the fluid is stale.

The fix for this issue is as easy as it seems: replace your transmission fluid with fresh oil of the right type for your model.

4. Hydro pump issues

Many users reported that their riding mower starts very fast, then slows down to a crawl while mowing, and it’s not a grass-related problem.

Once you ruled out the idea of the mower deck becoming lodged, it was probably a hydro pump issue.

The hydro pump can get worn out over time, and when it reaches its breaking point, it’s unable to pump the oil correctly because it’s too hot.

You might hear strange sounds as the hydro pump cries out while it tries to pump but cannot produce the necessary pressure needed to move the mower.

Once the hydro pump fails, the lifespan of your mower is considerably shortened, even if you manage to fix it.

Because of this, it’s essential to prevent hydro pump failure by routinely monitoring hoses, connectors, and oil levels so that you can identify issues as soon as they arise.

5. Transaxle issues

The transaxle on this model can be a pain because it was never meant to be serviceable.

The company itself suggests replacing it if something happens. That’s why it’s not easy to practice maintenance on the transaxle of the L120.

There’s also the problem that very few replacement parts are on the market, so that the situation can get expensive quickly.

However, the transaxle leaking from the rear end is quite a common issue and one that can cause problems with the hydro pump and, thus, with the overall functionality of the lawn mower.

When the oil in the transaxle is low, you might encounter this problem. Now, the transaxle doesn’t have a drain plug, so to drain it and refill it, you have to remove it from the mower.

You should probably seek the advice of a specialist on this as it can be quite a nuisance.

When the transaxle is removed, you want to check the oil level. The level should be only one inch down from the top of the vent plug hole.

The type of oil recommended in this case is Low Viscosity HyGard oil. Don’t worry about overfilling the component; it might leak from the top when it gets hot, but it won’t cause any damage.

John Deere L120 problems: are they a deal-breaker?

The John Deere L120, although cheap and seemingly the best choice for first-time gardeners, is not meant for those who don’t have long-time experience and are unwilling to do their repair work.

It seems that this garden tractor works well but also needs quite a lot of maintenance.

Sure, you might be one of the lucky owners who never encountered any serious issues, but we were talking about a model in production more than twenty years ago, so we’re going to be realistic.

In this case, we would say that the John Deere L120 issues can be a deal-breaker because why would you put yourself through this when you can purchase much better models, like the 3038E or the x300? You wouldn’t, simple.

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