How Lawn Mower Starter Works? The Ultimate Guide
Whether it is a lawnmower or other automobile, no engine can start unless it has a significant amount of power.
So, how lawn mower starter works? The engagement of the flywheel is essential to start the mower. The battery plays a major role in sourcing the power and involves the flywheel. Then the crankshaft begins to spin, which is supported by the flywheel. Unless you press the solenoid button, you can’t switch on the starter motor.
In this article, we will share how lawn mower starter works in detail. Read until we finish to learn some precise information about it. Keep scrolling!
- How Lawn Mower Starter Works?
- How To Bypass the Starter Solenoid?
- Step 1 — Checking The Battery
- Step 2 — Switching On The Ignition Key
- Step 3 —Finding Out The Lawnmower Solenoid
- Step 4 — Identifying The Copper Posts
- Step 5 — Cleaning The Terminals
- Step 6 — Giving A Final Finish
- Defective Battery
- Clean Leads
- Spark Plugs Issues
- Functioning Starter Solenoid
- Defective Battery
- Defective Solenoid
- Defective Ignition Switch
- Defective Starter Motor
- Step 1 – Disconnect Your Negative Cable
- Step 2 – Put a Bit of Loctite
- Step 3 – Install The Positive Battery
How Lawn Mower Starter Works?
After turning on the lawnmower mower ignition key, the engine starts to turn in motion and cranking. Do you think cranking is a simple process? No! It is a complicated process-not as easy as you think.
Unless there is the right level of air inside the engine, you will struggle to start it. No turn for the machine will occur if there is no airflow.
So, how does free airflow is achieved inside the engine? When the motor turns over and over, it creates suction. This helps to pass air inside the machine. If there is no air, the combustion of fuel won’t occur.
You can compare a lawnmower starter with a key of a locker. You are supposed to use the key to unlock the locker and then enter inside it.
After turning on the ignition key, the starter should work smoothly to turn over the engine. Only then can you start your lawnmower. When the starter works smoothly, you can do other things.
Lawnmower engines feature a flywheel that is mounted on the ring gear, and the crankshaft end is connected to it.
There is a pinion gear on the lawnmower starter, which is mainly located in the grooves of the ring gear.
The lawnmower starter receives energy after turning on the ignition key. The engagement of electromagnet also occurs.
A rod is pushed out from beneath the pinion gear that is connected to this. When the gear reaches the flywheel, the lawnmower starter will turn over.
As a result, the main engine will start spinning to collect air. Concurrently, spark plug wires convey electrical current to the plugs, and the combustion chamber receives fuel by the ignition process.
The starter disconnects once the engine is turned. Also, the electromagnet, which sends electricity through a coil of wire stops.
The rod pulls back into the lawnmower starter for another time to keep out of reach between the flywheel and the pinion gear.
If there is any connection between the pinion gear and the flywheel again, a Rapid engine spin for the starter will occur. It will ultimately cause damage to the starter.
So, this is the way how lawn mower starter works. Knowing the mechanism gives an entire idea of each part of starter functions and how they contact each other.
How To Bypass the Starter Solenoid?
Apart from knowing how lawn mower starter works, it is essential to understand how to bypass the starter solenoid.
Are you getting a clicking sound from your lawnmower but failing to start the lawnmower? The problem might be related to the starter solenoid or starter motor.
So, why does this happens? It mainly occurs when the starter solenoid is attempting to push for the engagement of the lawnmower machine. But, it may not happen if the starter solenoid doesn’t have enough power to move the gear for engagement. Also, the issue may seem if the starter solenoid becomes excessively cold.
One of the best methods to deal with this issue is by bypassing the starter solenoid. Wondering how to bypass the starter solenoid? Check out this step-by-step procedure to learn about how to bypass the starter solenoid.
Step 1 — Checking The Battery
First of all, you want to test the battery conditions whether it is working perfectly or not. You can use a multimeter or a battery tester to test it. The battery is supposed to read 12v if no issue with it. If it is okay, follow the next steps.
Step 2 — Switching On The Ignition Key
Try to turn on your lawnmower by pressing the “START” button. Despite receiving power, sputter would not begin
Now, you want to keep the ignition in the “RUN” option. By doing so, you allow the battery’s current to pass through the circuit.
Step 3 —Finding Out The Lawnmower Solenoid
Give your hands on the battery, which is mainly located below the mower seat. Now, find out the cable which is connected with the positive terminal. A cylindrical structure is attached to the positive terminal and has three or four wires connected.
Lawnmower solenoids either come with three-pole or four-pole. Common ground is connected to the three-pole solenoid, which is mounted on the mower. On the other hand, a special terminal is included for the ground on four-pole solenoids.
Step 4 — Identifying The Copper Posts
Two big terminals are equipped for a lawnmower solenoid, and each of them has large cables connected to them. One cable is connected to the battery’s positive terminal while the other one goes to the motor. In this case, these two huge
Step 5 — Cleaning The Terminals
Rust and dirt may store inside the terminals. You want to use a wire brush to get rid of them from inside and outside.
Step 6 — Giving A Final Finish
Now, you want to attach the positive terminal from the battery to the motor using a screwdriver. A complete circuit can be built this way, and the lawnmower will then start.
So, these are the complete steps of knowing how to bypass the starter solenoid.
What Are the Symptoms of a Bad Starter Motor on a Riding Mower Engine?
A riding mower engine is supposed to start smoothly if there is no issue with the starter motor. However, if there is an issue, you may struggle to start it or stop within seconds after running. What are the symptoms of a bad starter motor on a riding mower engine?
Here are the few common signs you will notice if you are wondering about,” What are the symptoms of a bad starter motor on a riding mower engine?”
Is the lawnmower battery working perfectly? Does it produce a sufficient amount of voltage? To learn about it, you want to use a battery tester or a millimeter to find out the voltage it is generating.
Each lawnmower battery must have enough voltage to help the starter motor to start the engine. If it doesn’t have enough voltage, you want to recharge or replace the battery.
Clean leads are necessary for the positive and negative wires, which are connected to the battery. With dirty leads, your lawnmower won’t be able to make nice electrical contact.
Make sure you regularly remove any corrosion or dirt from the cable clamps or battery posts using a wire brush.
Spark Plugs Issues
Have you checked the spark plugs of your lawnmower? They need regular cleaning for smooth operation. Check out any wear or fouling on spark plugs after removing the wires connected with them.
Carbonized or oily spark plugs can be the reason behind a bad starter motor. If your spark plugs are oily, it means piston rings already got damaged. Hence, changing spark plugs will not solve the problem unless you replace the piston rings.
However, replacing is a better option if you notice any wear or damage issues on the spark plugs. Start your lawnmower to see whether the lawnmower is working perfectly or not.
Functioning Starter Solenoid
A place between the starter and the battery is where the starter solenoid is located. It is a special switch. When you turn on the button, electric power is transferred to the starter motor to run the lawnmower engine.
So how do you test whether your starter solenoid is bad or good? After turning on the ignition key of your lawnmower, the starter solenoid jump. And, at the same time, closing the space between the two bolts on the solenoid will help you know the starter solenoid’s conditions.
While doing the test, if the engine runs, you might have a bad solenoid. Replacing it is necessary. However, the starter motor might be the main culprit if you fail to start the engine.
So, these are primary symptoms you will see to learn about “What are the symptoms of a bad starter motor on a riding mower engine?”
How To Start A Lawn Mower With A Bad Starter?
It is difficult to start your lawnmower with a bad starter. Various problems cause the starter to fail frequently. Here are the few common issues you may see if your lawnmower has a bad starter.
Cutting grass with a defective battery is not an easy job. The first thing you want to do checking if any leakage issue on the battery.
So, why leakage occurs on the battery? Most of the time, it happens when water enters inside the battery.
You can first try out sealing leaks of the battery. If it doesn’t work, you have no option but to replace it. Keep your hands and eyes safe by putting on gloves and safety eyewear when working with batteries.
Further, you want to assure the battery has a considerable amount of charge. If not, you want to use a charger cable to recharge the battery.
Aside from that, testing the battery voltage is another essential job you need to do. When it reads 12 volts on the tester, you can take it as a good battery. The battery is likely to have a problem if it doesn’t work.
If this is your first time locating a starter solenoid, you may find it challenging. You will either have to reach it by raising the front hood in the upper level or the rear wheel.
Follow the red wire on the battery if you are facing difficulty reading the directions. After finding the solenoid, inspect the conditions of the terminal attacher and screws that are connected with the solenoid. Tighten the screws if they are loose. But not overtighten them. Also, inspect the attacher.
Next, you want to turn on the lawnmower keys in the clockwise direction. Do you hear a clicking sound though the engine is not starting? If yes, replacing the solenoid is necessary.
Defective Ignition Switch
A defective ignition switch can sometimes cause a bad starter. By looking at the switch’s internal conditions, you can tell whether it is in good condition or not.
Inspect the switch from the backside and lower area. Make sure all wires attached with the switch are properly connected—no loose issues. Also, check out if there is any corrosion buildup inside it.
How to test a Lawn Mower Starter on a John Deere D100 100 series Briggs and Stratton 17.5hp
The ignition switch is often to blame for the problem with the starter if it is found to be defective. Replacing the ignition switch will help to deal with the issue.
Defective Starter Motor
You will struggle to run on your lawnmower if any issue occurs on the starter motor. Put your hands under the front hood, where you will notice the starter motor.
Typically, the starter motor and solenoid are connected together in the lawnmower. Take a jumper (a short length of the conductor) and connect the negative end with a screwdriver and the positive end with the jumper of the batter.
You are supposed to notice some sparks after attaching the screwdriver with it. You have no reason to fear a shock because 12 volts are not powerful enough to give you a shock.
If you notice the lawnmower is not starting even though you hear clicking sounds, replacing the starter motor is the best solution.
- It is the best rule of thumb to read all instruction manuals of each lawnmower part before starting the work. You will get a clear overview of them.
- Make sure you wear high-quality hand gloves and eye wears to protect your hands and eyes.
- Wearing a protective cloth is also appreciable if any unwanted accidents happen.
- Make sure you know how to use the screwdriver and multimeter.
- Kids should be away while doing the work.
Hopefully, you have learned about “How to Start a Lawn Mower with a Bad Starter?”
How To Replace A Lawn Starter? Step By Step
Apart from knowing how lawn mower starter works, it is also important to get an idea about how to replace a lawn starter.
Does your lawnmower have a problematic starter? When you try to start your lawn mower, all you hear is a grinding noise.
If your lawnmower starter has a problem, it will not appear to be engaging the flywheel. That’s the main issue with the starter.
Also, you may see the gear is stuck in the up position; there’s totally something wrong with that. Once the switch is off, that gear should be all the way back down. Additionally, the collar may not slide back down the shaft.
The most common reasons gardeners replace starters on the lawn are because they are burned out. People hold them way too long when the machine won’t start. This makes the starter overheat, and then eventually, it becomes completely damaged.
Step 1 – Disconnect Your Negative Cable
First of all, your negative cable needs to be disconnected from your battery. You are disconnecting the battery cable is for safety purposes as you don’t want a live positive wire.
Once you take it off at the starter dangling and touching the mower’s body, that would definitely cause sparks and a short. Next, you want to remove the positive battery cable here from the starter.
Step 2 – Put a Bit of Loctite
It is better to put a bit of Loctite on the bolts that hold the starter. You can use medium-strength Loctite, which makes the starter easy to install. You just line it up to the two holes underneath the starter and serve your bolts.
If your holes aren’t quite lined up properly, just move the starter a bit to get it in and install the bolts evenly. Make sure they are tightened fairly.
Step 3 – Install The Positive Battery
Then, install the positive battery cable on the starter and undo the nut. Before reconnecting the battery cable, it’s best to clean the posts and get rid of corroded bolts. With a wire brush and a drill, you can clean it.
Now you can add a bit of dielectric grease on the posts if you want. This will help prevent corrosion. So, removing and installing a new lawnmower starter is done. Now you can try to start the mower.
Are you still wondering how lawn mower starter works? We have already covered everything about this topic. Hopefully, you have learned many precise details on how lawn mower starter works. Thanks for reading!
Last update on 2023-01-28 / Affiliate links / Images from Amazon Product Advertising API
Lee Safin was born near Sacramento, California on a prune growing farm. His parents were immigrants from Russia who had fled the Bolshevik Revolution. They were determined to give their children a better life than they had known. Education was the key for Lee and his siblings, so they could make their own way in the world. Lee attended five universities, where he studied plant sciences and soil technologies. He also has many years of experience in the U.S. Department of Agriculture as a commercial fertilizer formulator.
Thoughts on “How Lawn Mower Starter Works? The Ultimate Guide“
How to Start a Lawnmower with a Bad Starter?
All homeowners with lawns know pretty well that lawnmowers are unmatched machines for tending your yard. But it is only fun when the mower is working fine and smooth. When a mower is not running correctly or having problems, mowing becomes tedious and rather unenjoyable. Lawnmowers, like all machines, run into all sorts of issues. But could there be a more frustrating problem than the mower not starting at all? One of the reasons for this could be a bad starter. But don’t worry, even with a bad starter, there are ways to start your mower.
How to Start a Lawnmower with a Bad Starter:
- Clean the battery leads and seal any leakages, then try again. Replace the battery if it is faulty beyond repair.
- Bypass the solenoid and start the mower using the starter motor only.
- If the starter motor is faulty, you’ll have to get a new starter motor.
- Replacing the entire starter with a new one is better than replacing just the motor.
- In case of a faulty ignition switch, try to make its connections tight. If it is defective beyond repair, get a new ignition switch.
Reasons for a bad starter:
The starter is responsible for using the energy of the battery to start the engine. A bad starter won’t do this job, and the ignition system won’t get any energy, which means that there will be no spark and the engine will not start. A starter can go wrong because of these causes:
The final solution to a bad starter can be to replace one or more parts, but techniques like bypassing the solenoid can let you start the mower for now, and you can do the replacement later. To do that, you’ll need to get some basic information about a starter and its working. This article will surely help you in this regard.
What is a Starter?
The starter is an essential component in a lawnmower that transfers electricity from the battery to the ignition system, thus allowing the engine to start. A starter has two main components, a starter solenoid, and a starter motor.
Solenoid gets current from the battery and transfers it to the motor. When the ignition button is pushed, a current is sent from the battery to the solenoid through the wiring and then from the solenoid to the motor.
The starter motor is the starter component that is linked directly to the spark plugs. It sends current from the starter to the engine.
These two components are independent but work together to power the spark plug so that a spark can be generated in the combustion chamber, producing power from fuel. Though the starter solenoid and motor are independent, the chain is disrupted if one fails, and the engine won’t start when you push the ignition button. But because these two components are separated, the mower can still be turned on if one goes bad.
Before making any repairs or changes, you need to know what’s wrong. A lawnmower with a bad starter will show specific symptoms that can help you see the problem’s root cause.
Symptoms of a Bad Starter:
A satisfying rumble sound is always expected when starting the engine, but a mower with a bad starter will make abnormal sounds when it is being started. The sounds can be used to judge the nature of the underlying problems.
Abnormal Solenoid Clicking:
When the ignition button is pushed, the solenoid transmits an electric spark that starts the motor. The motor starts rotating a smaller gear that engages with a larger gear of the engine. This is how the engine is jump-started. When this process goes normally, a clicking sound is produced, followed by a whirring sound that indicates that the starter motor is engaging with the engine.
If you push the ignition button and only the clicking sound is produced, it is a sign that something is wrong and the motor is not engaging with the engine’s gear.
Whirring sound, but no Catch:
When the whirring sound is produced but is followed by a loud rumbling sound, it is a sign that the starter is not engaging with the engine in the normal manner. This is a sign of the starter’s smaller gear not correctly engaging with the engine’s gear. Another sign of this issue is when the engine starts but stops after just a moment. Broken teeth basically cause these problems on the starter motor’s gear or worn motor brush brushes. If this is the case, these faulty components will have to be replaced.
Not Starting Even with a Fully Charged Battery:
If your mower does not start even though there is no battery-related issue, it is the clearest and obvious indication that the starter isn’t working fine. When this happens, start looking for the cause of problems right away.
Solenoid Not Clicking:
If there is no solenoid clicking sound when you push the ignition button, it is an indicator of loose connections to the solenoid. This means that the current is not reaching the solenoid. If this is the case tightening solenoid connections will get your mower running.
Starting a Mower with a Bad Starter:
A bad starter is caused by electrical problems that can be fixed. Here’s a guide on how to do that.
Flat or Faulty Battery:
The first thing to get in order when your mower is not starting is the battery. If the battery fails to provide electricity, there is no way your mower will start.
Start by looking for leakages. Charge the battery with a charging cable, and if it becomes wet, then the battery is leaking. Small leakages can be sealed, but if the leak is too big, replace the battery. When dealing with leaks, wear safety gloves and glasses to avoid acid burns.
Check the battery voltage too. The battery voltage should be 12V. If the voltmeter reading is less than 12.4V, it is a sign of a faulty battery that needs to be replaced.
Loose connections of the ignition switch wire or corrosion on the back part of the switch can also cause a bad starter. If the issue is not of a severe nature, you can fix it yourself. If the ignition switch has become so bad that it can’t be repaired, it should be replaced with a new one.
The starter solenoid is a mounted switch that provides current to the engine’s starter motor. The solenoid has four threaded electrical lugs connected to the battery, ground, ignition switch, and starter motor.
Different lawnmower models have their solenoids at different locations. You can locate the solenoid in your mower by following the red battery wire. After locating the solenoid, check its connections and screws and tighten them using a wrench or a plier. Rotate the ignition key. If the solenoid clicks without starting the mower, the solenoid needs to be replaced.
The starter motor is attached to the crankcase of the engine. If you have already checked the components mentioned above and they are fine, but your mower is still not starting, the chances are that its starter motor is faulty.
To check the starter motor, connect it to the battery using a jumper cable while attaching a negative terminal screwdriver. You’ll see some sparks, but there is no danger of shock from a 12V battery. If the motor doesn’t start and gives clicking sounds, the motor is faulty.
Sometimes the winding, magnet, brushes, etc., inside the mower can get dirty or burn during use. Fixing them can solve the issue too.
A faulty motor can be rebuild. But this has to be done by a professional electrician.
Bypassing the Solenoid:
Like said before, the starter solenoid and motor are two independent components. If you have determined that only the solenoid is faulty, you can try to start the mower using the starter motor only.
A solenoid has wire connections from the battery/ignition switch. To bypass the solenoid, connect these wires to the motor using a metallic connection. Then try to start your mower. If it produces a whirring sound, it means that the mower can be started. You’ll need to try a couple more times to start the mower.
Use protective equipment while bypassing the solenoid.
The lawnmower not starting on a potentially enjoyable mowing day is very frustrating. Mowers fail to start when their starters go bad. But most of the time, starter problems are not too complicated and can be fixed by the user. Follow the guidelines mentioned in this article to get your mower running once again. Checking other electrical components such as spark plugs will help too.
Starter Replacement Guide – John Deere Lawn Tractor
The starter on my John Deere LX172 lawn mower finally gave up the ghost. Here is a quick and easy picture guide for replacing the starter on this lawn tractor. I’ve included photos of the steps as well as the socket sizes needed for all the nuts and bolts, I hope this helps make this job go a little quicker for someone out there!
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RIDING LAWNMOWER WON’T START. Is it the SOLENOID or Starter Motor? HOW TO TEST
Part Numbers for Replacement Starters
Check the model number of your John Deere tractor. Depending on the engine and model number, you may need one of the following starters:
- Starter John Deere Lawn Tractors 170, 172, 175, 240, 245, Kawasaki (14HP Engine)
- OEM part numbers: 12498-63010, 128000-4020, 21163-2073, 21163-2073A, AM104559
- Specifications: Type: DD, 12v, 0.7 kW, CCW rotation, 9 teeth/splines
- OEM part numbers: 390838, 391423, 392749, 394805, 491766, 497594, 497595, 693054, AM122337, AM37352, AM39137, LG497595, SM01965, 410-22003, 410-22003R, SBS0001, 5742, 5742N
- SPECIFICATIONS: 12 Volt, CCW, 16-Tooth Pinion, PMDD, 12v, CCW rotation, 16-teeth
How to Replace the Starter on a John Deere Lawn Tractor
Here is a quick summary of the steps, I go into more detail with the photos below, but sometimes it is good to have a summary with the nut and bolt sizes:
- Turn the key to the “off” position.
- Open the hood of the lawn mower.
- Remove the negative battery terminal.
- Locate the starter and disconnect the wiring harness by pressing the plastic tab and pulling it off.
- Disconnect the battery cable going to the solenoid using a 14mm socket.
- Remove the 2 starter mounting bolts (12mm).
- Slide the starter off of the engine.
- If you are only replacing the solenoid, remove the two 10mm nuts to remove it and swap with the new solenoid.
- Put the new starter on by reversing the steps.
Step by Step Instructions for Changing the Starter on a Lawn Mower
The unit I am working on is a John Deere LX172. Here it is with the hood already removed.
Turn the key to the ‘off’ position and raise the hood.
Here is a closer view of the Kawasaki engine.
Disconnect the negative battery terminal.
Locate the starter. This is a closer view of the starter location.
Disconnect the plastic wiring harness. It has a clip you should press, then pull it down and off.
Remove the positive battery cable using a 14mm socket or wrench.
Remove the two 12mm mounting bolts from the top of the starter. Slide the starter down and away from the engine.
Here is a picture of the starter once it is removed.
The part number for the new starter is 21163-2073, and here is the link:
Make sure you order the correct starter.
The correct starter for my tractor was the 21163-2073, which is stamped on the original:
I mistakenly ordered the wrong on originally. Here is a photo of the original starter (top) alongside the incorrect starter (bottom):
The starters look the same from the bottom. The main difference is the mounting hole spacing, and the fitment ring which is too big on the lower one in the picture.
For reference, the starter I needed was the 21163-2073.
The incorrect starter for me (bottom one in the picture) was this style.
The teenage son walks into the living room and tells his father, “Dad, the car won’t start, there’s water in the carburetor.” The father, knowing that the son is not very mechanical, looks confused, “Water in the carburetor, that’s ridiculous!” But the son insists, so the father continues, “You don’t even know what a carburetor is, but I’ll check it out. Where’s the car?” The son replies, “In the swimming pool.”
If you only need to replace the solenoid, remove the two 10mm mounting nuts, and the 14mm grounding nut at the bottom. The correct solenoid is this one:
To put on the new starter, reverse the steps described.
I hope this helped save you some time and effort!
The Starter Relay and Why a Mower Won’t Start
A lawnmower requires several amperes of electrical current to start the engine. For safety reasons, a lawnmower (and other electric-start internal combustion powered vehicles) contains two parts to the starting circuit: a start switch circuit and a relay circuit. Since an electromechanical relay can only be used for a specified number of cycles before failure, a faulty starter relay can prevent a lawnmower from starting.
Why a Lawnmower Contains a Starter Relay
A relay allows a low-power, light-duty switch to actuate or disengage the starter circuit without being directly wired to the starter circuit itself. If the lawnmower starter circuit did not contain a relay, heavy-duty wiring would have to be wired to the lawnmower starter switch. This would pose a potentially fatal shock hazard if the starter switch or starter circuit wiring became damaged. The starter switch would also be prone to electrical arcing and excessive heat, which would eventually destroy the switch and potentially damage the lawnmower.
- A lawnmower requires several amperes of electrical current to start the engine.
- For safety reasons, a lawnmower (and other electric-start internal combustion powered vehicles) contains two parts to the starting circuit: a start switch circuit and a relay circuit.
Why a Bad Relay Prevents a Lawnmower from Starting
When the starter switch is turned on, the switch circuit provides power to an electromagnet inside the relay. This electromagnet pulls the relay switching mechanism closed and engages the relay circuit. The relay circuit provides power from the battery to the starter.
If either the electromagnet or the switching mechanism in the relay is faulty, the relay circuit will not engage. This prevents electrical current from flowing to the starter from the battery.
Why a Bad Switch Prevents a Lawnmower from Starting
Since the switch circuit provides power to the electromagnet in the relay, the switch circuit is just as important as the relay circuit. If the switch is broken, the switch circuit will not provide electrical current to the electromagnet. Without electrical current flowing through it, the electromagnet will not work and the relay cannot be actuated.
Both the switch circuit and the relay circuit require a power source and transmission lines (wires) to operate properly. If there is a break in the wire on either side of the circuit, or if the power source connection is loose or faulty, this will prevent the lawnmower from starting as well.