Last Updated on September 28, 2021 by Mark Brian
A riding lawn mower is essential when it comes to mowing large areas of grass. Imagine making all the necessary preparations for a mowing session, and then the engine won’t even start. It might be that the riding lawn mower’s engine is seized.
So how will you know it is specifically a seized engine? Well, grinding engine noise with stuck blades is the first sign. In addition, the piston will stop working so the oil doesn’t circulate properly, giving way to a locked engine.
However, we have got you covered to correctly identify and unseized a riding lawn mower engine, all on your own without a mechanic. So, let’s get going.
What is a seized engine?
When a riding lawn mower’s engine won’t start, basically due to low oil supply it is seized. The mower blades won’t move at all. It doesn’t mean that the engine is broken but due to some technical fault, it won’t turn on.
How to spot a seized engine?
There can be several reasons for the engine to stop working. Moreover, we can rectify the reason for seized engine by checking various components one by one. However, some tell tale signs to spot one are the following:
Jammed mower blades that don’t even budge when the force is applied, signal towards a seized engine. Also, any old buildup or debris stuck between the blades can also cause this problem.
Engine Won’t Start
In most cases, the riding lawn mower’s engine won’t start when the cord is pulled. Besides the cord is so tight that any further use of force can risk it breaking.
Engine oil plays a primary role to ensure good engine performance. So poor oil quality with impurities can damage your machinery. Mostly because the buildup of debris in the engine affects the smooth motions and results in a seized engine. This is why premium quality engine oils are often recommended.
Another scenario for the seized engines is that the engine does start, but it shuts down right after. You will notice a grinding noise of machinery rubbing with each other. It is not advisable to start the engine repeatedly if it gives off such sounds or any smoke. A smoking engine is an alarming situation. Looks like you will be risking the wear and tear of the engine’s internal components.
Alternatively, it could be the piston jammed in the cylinder and thus unable to move. This may happen if the lawn mower was not used for a long time. Another reason could be the lawn mower’s exposure to muddy and uneven terrain where the water got stuck in the engine seal.
If water gets stuck in the seals, the valves will burst or give way to water into the engine. Such damage can free the piston and lead to oil wastage. Thus, it can leave the piston unlubricated and stuck, causing the engine to seize.
One of the major reasons is the decreased oil level in the engine. The main combustion chamber needs sufficient lubrication to produce energy. Decreased lubrication of the piston can jam it. So draining all the oil in a canister and checking its level is one way to make sure if the oil level is decreased or not.
How to unseize a riding lawn mower engine – Step by Step Guide
Now that you know some possible reason for the engine to be stuck. All you will need is a good quality engine oil, preferably recommended for your brand of lawn mower and a penetrating oil spray can. Feeler gauges and sprays like WD 40 can also come in handy.
Following are the steps to unseize a riding lawn mower engine like a breeze.
1. Remove Spark Plug
First, you will need to remove the spark plug from a seized lawn mower engine. Sometimes the technical defect is in the internal machinery, so to avoid any short circuits or accidents, the spark plug is removed.
Next, try to pull the cord and see if it makes any sound. If there is no sound, then just clean the spark plug. For this purpose, tilt the lawn mower and unscrew the spark plug to clean it.
Also, check for the gaps between the chambers. If the gap appears more than usual, it is high time to replace the plug with a new one.
2. Use Penetrating Oil Spray
Once the spark plug is clean, make sure that the engine is well lubricated. Often the piston or the engine chamber is stuck because of low oil supply. However, before you jump to engine oil, clean the engine with a penetrating aerosol spray, usually WD 40 or Blaster PB.
The purpose of such spray is to thoroughly clean the engine and remove any rust that might be forming in the engine. Although it cannot avoid the damage already done, it can lessen the chance of rust from forming further.
Moreover, such sprays give off toxic fumes so use an airtight mask when applying them. Leave the fluid in the tilted lawn mower for some hours to work properly.
3. Clean the Debris
Once you have let the riding lawn mower rest for a while, drain the lubricant spray from the engine. Now try to move the blades in the direction of their movement slowly. Do not apply too much force, however, if the blades still don’t move proceed to clean the engine.
You will need to remove any grass, or mud that might be stuck or solidified in the engine chamber. Long periods of inactivity, usually after months can cause this. Carefully remove and drain all debris with old crude oil. However, make sure not to use water in the process.
4. Move the Piston
In most cases, it is just the lack of proper lubrication but if this doesn’t solve your problem, open the head of the engine. Remove the seat from the mower. This will expose the piston cylinder, give it a bump on all sides with a hammer so all the jammed parts get loose.
Next, gently check all the seals, if any is broken or lose then replace them. By opening the crankshaft you will have a better understanding of what is stuck.
So clear all the crude oil that comes your way, lubricate the engine with cleaning spray, and let it bask in the sun. Also, make sure that the piston has not become free in the cylinder.
5. Close the Open Parts
Every part of the engine is important to its function when it comes to a riding lawn mower. This is why returning the designated compartments to their place is necessary.
After you have let all the components of the engine clean, lubricated, and dry, return them to their place. Close the head of the engine and let the lawn mower rest for a few hours before turning it on.
By now your riding lawn mower’s engine should be unseized. To keep it in the working form and avoid another seizure, use good engine oil with a crude free lubricant. Also, run the lawn mower on easy settings for a week to reach its maximum potential.
For seized engine prevention, you can follow the steps mentioned below:
Just like any other machine, riding lawn mowers also require periodic service. If you don’t want to pay some extra cash for it, then you can do it yourself. Clean the engine every once in a while like mentioned above. Also, remove and clean the air filters, sharpen lawn mower blades with a grinding wheel and you are good to go.
Regular Oil Change
Crude and greasy oil is the nemesis of any petrol run lawn mower engine. So make sure that you use a recommended grade engine oil with crude free qualities. Regularly changing oil and oil filters can extend the life of the lawn mower.
Avoid Stress on Engine
Overworking the engine beyond its capacity can severely damage it. Therefore, mow the lawn within the capacity of the mower with enough breaks to avoid overheating. This way you can ensure the quality as well as safety of the engine.
Check Coolant Level
Most of the three blade lawn mowers have airflow technology. However, some riding lawn mowers use liquid engine coolant to keep them from overheating. So checking the coolant level before each mowing session and refilling if necessary can help prevent a seized engine.
Frequently Asked Questions (FAQs)
What causes the engine to seize?
There are a lot of factors that contribute to the seized engine of a lawn mower such as long inactivity, overworking, overheating, or a broken engine belt. Usually, it is the lack of engine oil or proper lubrication that causes it.
Can I fix a seized engine?
Yes, you can fix a seized engine with minimum tools. If the reason is lubrication, proper cleaning and oiling will unseize the riding lawn mower’s engine.
How much does it cost to unseize an engine?
You can expect to spend between $50 to $100 on penetrating spray and some common use pliers if you already don’t have them. However, if the seized engine is beyond repair, a total replacement may cost somewhere between $2000 to $3000.
How long does it take for an engine to seize without oil?
Technically, an engine can work for an hour or two without oil. However, using an engine without oil will damage it irreparably and the whole thing may fall apart at high speed. So, never use an engine without oil or a lubricant.
What happens if you go too long without an oil change?
The basic purpose of oil is to keep the engine from overheating and working smoothly. At the same time if the oil becomes too old, and forms sludge it will no longer cool the engine and may result in damaging or hindering the engine.
You can save your investment by learning simple steps on how to unseize a riding lawn mower engine. We have tried to cover all the basic preventive steps to help you along the way. If you have any questions, feel free to ask. We will be happy to help.