John Deere Mower Won't Start But Just Clicks? (We Have a Fix!)

Ryan Womeldorf
by Ryan Womeldorf
John Deere mowers are reliable, that is until they fail to start and simply click. This can happen for several reasons, such as a loose battery or faulty solenoid. Whether it be poor connections or a mechanical error, let’s explore why your John Deere mower won’t start and just clicks.

Riding lawnmowers may cost a bit more but will ultimately result in greater convenience particularly for larger plots of land. Like your standard push mowers, riding mowers come with a variety of components that can ultimately break down and stop working properly.

A John Deere mower can click without turning on if you have a loose battery connection or a bad solenoid. A faulty start motor can also cause it to click without starting. Excessive lash between the rocker arm and valve tip can keep your John Deere mower from starting.

If your John Deere mower won’t start and just keeps clicking, here are a few reasons this could be happening.

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Bad Battery Connections

In most cases, the reason for the clicking when the engine doesn’t start is due to some sort of battery connection issue. These are very common issues and most of them can be addressed through some amateur troubleshooting.

Typically, a bad battery connection means that the power isn’t passing from the battery through the cables. More often than not, the reason is due to a loose or faulty connection, though they can also be excessively dirty or damaged as well.

Loose Connections. When your riding mower vibrates a lot, the battery cables could start to come loose. Servicing your motor prior to the start of each season is a good idea, regardless of how well it is running. While those loose connections are not a big deal, they can lead to worn cables that deteriorate to the point of not being usable.

Dirty Connections. When talking about dirty connections, it isn’t necessarily indicative of the amount of dirt on them. No, these are usually the cause of what is known as a weeping battery. This is where battery acid is starting to drip down near the poles. This acid then begins to crystalize, which causes higher resistance levels. If you have noticed a chalky, white substance on the battery (or a car battery), that’s what it is.

Cleaning the Connections

More often than not, you can simply clean the connections to get them working properly once again. In order to clean them safely and securely, just mix a little bit of water together with a few spoons of baking soda.

1. Pour the Mixture. Simply pour your mixture over top of the acid buildup on your individual connections as well as on each of the battery poles. The baking soda is there to neutralize and remove the acid. Handling the acid requires proper protection, so make sure that you are wearing gloves and proper eyewear.

2. Clean the Connectors. When the acid has been removed, remove the connectors to give them a good cleaning separate from the other components. You can do this using sandpaper or a wire brush to get the built-up grime, dirt, and debris.

3. Use Petroleum Jelly. Before returning the connections back to their proper positions, use some petroleum jelly to provide a thin coating. The petroleum jelly should help to prevent buildup of acid, dirt, and grime in the future.

Bad or Flat Battery

When the issue resides with the battery itself, it can be a real pain. Not only that, but it can also be quite a bit more costly to resolve than a bad connection. Generally speaking, the quickest way to solve a battery issue is by jump-starting it.

For long-term maintenance and care, take a look at your battery to see if any of the following issues are taking place.

Fixing a Bad or Flat Battery

1. Check for a Battery Leak. Before you attempt to jump-start your riding mower, check to see if there are any leaks in or around the battery. If it’s a sealed battery and there is noticeable leaking, you will have to replace the battery entirely. Typically, only wet batteries will leak, though, so check out the electrolyte level and top it off if you need to.

2. Practice Safety. Be certain to wear protective gear when dealing with battery acid. It can burn your eyes and skin, so wear gloves and protective eyewear. Should the build-up of battery acid be substantial, the battery should be replaced. Even if it works for the short-term, you can’t be certain that it will hold up for much longer.

3. Don’t Jump Start When a Leak is Present. You should not jump start a battery with excessive leaking. Replace the unit, ensuring that the battery is the proper size. Also, make certain that the poles are connected in the proper place as this is a common issue.

Jump-Starting the Mower

1. A 12-volt vehicle. To do so, you will need jump leads as well as a 12-volt vehicle. Most of the cars, trucks, and some hybrid cars out there will have a regular 12-volt battery so you can use that; it is just a matter of locating it.

2. Look for the sticker to identify. If you aren’t quite sure of what the voltage on a particular battery is, there should be a sticker somewhere on the casing. Look for that sticker before moving forward to verify that it is of the 12-volt variety.

3. Jumping is short-term. Keep in mind that jump-starting is generally a short-term solution. It may get you rolling right then but the battery is still most likely faulty and should be replaced sooner rather than later. You can use a battery test tool to check your battery before replacing it.

Solenoid Issue

Another reason that your John Deere riding mower may be clicking but not starting is due to the solenoid. The solenoid is essentially a relay: when the key turns to start eh motor, the battery supplies voltage to the ignition switch which then provides voltage to the solenoid.

The job of the solenoid is to connect the battery to the starter and turn the engine over, cranking it for as long as the key is held. That clicking sound that you’re hearing is the solenoid trying to do its job by pulling in the armature. Those can fail fairly regularly and require replacement.

Fixing the Solenoid

1. Locate the solenoid. For most riding mowers, the solenoid is located in a black device bolted near the engine. If not, it is bolted near the battery compartment.

2. Inspect the solenoid. Look over the condition of the solenoid. Make sure that there is no visual wear and tear or cracking in the component.

3. Test it out. If the solenoid looks fine to the naked eye, give it a test. You can test the solenoid by turning the key and listening. If the clicking is persistent, replacing the solenoid is the logical answer.

Binding Start Motor

The gear head, which is located in the starter motor, can ultimately bind against the flywheel. When that happens, the engine locks up in conjunction with the starter motor. When you turn the key, this could be a major reason why you are hearing the clicking noise.

Fixing a Binding Start Motor

1. Test the problem. Start by turning the engine by hand counterclockwise. Depending on your model, the engine may have a cover over the flywheel. If it does, try to turn the crankshaft using a socket wrench on the underside of the engine itself.

2. Spray some WD40. Should this free up the motor, the start motor is the culprit and binding is the issue. You can resolve the issue by spraying a little bit of WD40 on the starter gear head to loosen it. You can try to get the straw of the WD40 canister into the gear head without having to remove the cover if you’re lucky.

3. Allow time to dry and try again. Starters can bind for a number of different reasons. In addition to the reason mentioned above, it could be due to a worn gear head, worn bearings, or even a loose or misaligned starter motor.

Excessive Valve Lash

Each combustion engine has valves in it that open and close in sequence. The inlet valve is what allows a mixture of air and fuel into the engine, closing off and then sealing the combustion chamber. Then there is a power stroke, where the exhaust valve opens up and excises all of those spent gases.

Excessive lash is a very precise gap between the rocker arm and the valve tip. When the engine wears down, the gap gets bigger and bigger and has to be adjusted. Check your user manual; the exhaust and inlet valve lash will likely be comprised of different specs.

How Does the Valve Lash Work?

When the valve lash is properly set, the engine is cranked open, the valves open up, and the cylinder pressure is released. This is what allows the engine to crank over with enough speed needed to create a spark that is strong enough to start the engine.

Whenever the valve lash gets to be out of spec, the valve will be late opening. That means that the pressure in the cylinder will be too great to overcome and you will hear the clicking noise that has become all too familiar.

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Final Thoughts

With a little basic knowledge and some troubleshooting, most of the issues with your mower are inherently fixable. When in doubt, a certified technician can handle the more difficult issues and get your John Deere running again.

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Ryan Womeldorf
Ryan Womeldorf

Ryan Womeldorf has more than a decade of experience writing. He loves to blog about construction, plumbing, and other home topics. Ryan also loves hockey and a lifelong Buffalo sports fan.

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