14 Common Problems With John Deere 100 Series

john deere 100 series problems

If you own a John Deere 100 series lawn mower, you might come across some problems from time to time. This guide is designed to help you troubleshoot the issue so that you can quickly resolve the problem and go back to cutting your lawn.

Common problems with John Deere, 100 Series lawnmowers include engine issues, rust damage, blunt blades, uneven grass cutting, lights not working, or excessive noise and vibration. All these problems can be overcome with a bit of know-how.

Different Types Of Engine Problems

Like all engine-powered equipment, there may come a time when the engine on your John Deere lawn mower may not behave as it should. Let’s look at some more common problems and how to resolve them, as John Deere 100 series troubleshooting isn’t always easy!

The Engine Won’t Start

This could be caused by a faulty starter or a problem with your fuel delivery system.


Check the starter on your engine to see whether it’s working correctly. You might need to change the spark plug as these wear out over time.

You might also have an issue with the fuel delivery system, so it might be a good time to check the fuel pump and ensure that the hoses are clear.

The Engine Constantly Stalls

If your engine is constantly stalling, it could be a blockage in your carburetor or a choke plate that is not working correctly.


Check to see whether the carburetor is clean and clear of any obstruction.

Check the choke plate, as this may be causing an issue by not adequately regulating the amount of fuel that enters the combustion chamber of the engine.

The Engine Refuses To Idle

This common problem is usually the result of a faulty spark plug. 


Remember that spark plugs wear out over time and should be replaced periodically.

A Distortion In The Running Of Your Engine

This could be caused by an issue with your muffler. 


Check to see that no loose clamps or screws that could be causing the muffler to vibrate. 

The Engine Runs Rough

When your engine runs rough, it could be caused by a loose gas cap, blunt cutting blades, or some debris that is clogging up the fuel delivery system.


If your engine is not running as smoothly as it should, then there could be several ways to fix this. Firstly, you want to check that the gas cap is tightly closed. If this cap is not closed tightly, it can cause some of the gas to evaporate, and also dust and dirt could get into the fuel.

You should also check that your cutting blades are sharp. This is because dull blades will make the engine work harder. It will draw in excess air, and this causes a build-up of carbon within the combustion chamber. This carbon build-up could even damage your spark plug.

You also want to check that nothing is clogging up the fuel delivery system or any other part of the engine. It’s essential to keep the working parts of your mower clean and free from debris.

There’s A Knock In The Engine

Often, this problem is caused by a low fuel level or if you run the engine slowly for an extended period of time.


To remedy this, check the fuel level and give the engine more of a workout.

Your John Deere Engine Seems To Be Using A Lot Of Fuel

If you find that your John Deere engine is using way more fuel than it should, this is probably caused by an incorrectly working fuel filter. It could also be that your carburetor is clogged or that you have a faulty fuel line.


  • Check the fuel filter and replace it if necessary.
  • Check the fuel line to see that it’s clear.
  • Change the oil in your engine so that it runs more efficiently.

There’s Black Smoke Billowing Out From The Back Of Your Mower

A dirty air filter often causes this, or your engine might need an oil change.


  • Clean the air filter or replace it.
  • Change the oil in the engine.

The Engine Is Overheating

There could be a number of reasons for your engine to overheat. Your carburetor could be clogged, you could have a dirty air filter, your engine oil could be low, you’ve run your engine for an extended period of time or you’ve been working in wet conditions.


Check the carburetor to ensure no dust, dirt, or other debris is clogging it up.

Change the air filter and clean out the air hoses.

Check the level of the engine oil and adjust accordingly. A too-low or too-high level could cause the engine to overheat.

Make sure that you don’t run your John Deere at low RPM for long periods. 

Try to avoid mowing the lawn when the grass is still saturated from recent rainfall.

It might also be wise to take your mower to a mechanic to get it fully serviced and to check that there are no serious problems.

The Engine Is Excessively Noisy

If you find that your mower engine is excessively noisy, you might have a worn muffler.


  • Replace the muffler with a new system.

Rust Problems That May Cause Engine Failure

It’s essential to care for your John Deere well and to store it correctly out of the weather. If you don’t do this, you might end up with the gas tank rusting. If this happens, you’ll find that sediment will build up around the valve and cause engine running problems. If you don’t use fuel additives, you could also have this problem with rust.


Open the gas cap and turn over the engine without engaging the throttle. This may force any debris out of the engine and other areas.

Use fuel additives in the tank, and make sure you store your John Deere undercover and out of the weather.

Mobility Issues

Sometimes, you might find that your mower will not move forward. This could be caused by some issues, such as an inappropriate throttle position and cutting blades that are blunt or uneven ground.

You might also come across an issue where the mower vibrates and makes it uncomfortable for you to operate. Worn tires generally cause this.


To fix the throttle position, you can either turn on the mower with no throttle engaged in order to force out any debris or open the gas cap before turning on the engine in order to adjust the throttle settings. Consult your owner’s manual for ways to do this.

Check the cutting blades to see if they’re blunt. If they are, either have them sharpened professionally or replace them.

If you’re on uneven ground, the tires may not be able to gain enough traction to move forward. In this situation, you might have to move the mower onto more solid ground manually.

Replace the tires with new ones if they’re worn and your mower vibrates.

Cutting Issues

Sometimes, John Deere owners may find that their mower is not cutting the grass evenly. This is commonly caused by worn or blunt-cutting blades.

You might also come across the problem of your mower deck not rotating. Loose screws and bolts commonly cause this.


  • Have the blades professionally sharpened or replace them.
  • Tighten the screws and bolts on your mower deck so that it can rotate effectively.

Electrical Problems

If you’re trying to mow at night and find that your lights are not working, it could just mean that the bulbs need replacing.

If you have issues with the batteries not charging, they could need replacing.


Replace the bulbs and make sure your lights are turned on.

Replace the batteries if they fail to charge correctly or hold a charge.

Frequently Asked Questions

Who makes the engine for the John Deere S100?

The John Deere S100 engine is made by Briggs & Stratton. 

How many hours do John Deere mowers last?

On average, a John Deere mower is expected to last for around 8 to 10 years. This equates to about 4,500 to 5,000 hours.

Does John Deere S100 have easy change oil?

Five of the eight John Deere S100 mowers have the Easy Change 30-Second Oil Change System.

Final Thoughts

The John Deere S100 is a powerful mower that should last you for many years of happy mowing. However, from time to time, you might come across an issue. Most of these are easily fixed at home but remember that you should take your mower to be serviced professionally if you want it to last for the longest time.