Push mower engine seized. How To Troubleshoot a Lawn Mower Engine That Only Turns Halfway

How To Troubleshoot a Lawn Mower Engine That Only Turns Halfway

Have you ever experienced a situation where your lawn mower is hard to start, or the mower engine does not turn over completely and only turns halfway? If yes, it must have held you wondering whether it is possible to troubleshoot engine trouble and if possible, how to troubleshoot a mower engine that only turns halfway?

First, remove the whole Hood Assembly, Hood, Spark plug check the existing Gap between the Valves. Then, adjust the Top Valves in the Primary, as well as the other Valve on the Intake Cam, and clean the Exterior Parts. Finally, reinstall all the Parts test the Engine.

Keep reading this following article and learn the detailed way of troubleshooting a mower engine only turns halfway.

What Causes the Problem?

If your lawn mower engine suddenly stopped working as it is supposed to and does not turn over all the way, it might be due to improper adjustment of the valves on the primary and intake Cam because overhead valves prevent the mower engine from working properly.

Such commotion can also arise due to other potential defects like loose, dirty, or disconnected Spark Plug and clogged or dirty Air Filter.

It might be occurring because the fuel is not reaching the engine as it is supposed to, and in that case, you need to inspect the fuel condition, flow, fuel lines, fuel filters, and carburetor to confirm whether there’s any chance of leaks or blockage.

Steps to troubleshoot a mower engine that only turns halfway:

Lawn mower users often encounter a common issue as their mower gets older overtimes and that is the mower only turning over halfway and then abruptly shutting off.

Isn’t it too annoying to handle the middle of nowhere?

That’s why I have decided to present a quick, easy, and cost-effective DIY method of troubleshooting a lawn mower that only turns halfway.

Things required to troubleshoot:

Have a proper glance at the required tools and materials:

Tools Materials
Torque Wrench with a t25 Socket bit RTV Silicone
A t20 Torx Screw driver 3m Scotch Brite pads
10-millimeter Wrench New Gasket (if required)
A quarter inch Ratchet with an extension New Spark Plug (if necessary)
10-millimeter Socket Card Cleaner
Feeler gauge
3/8 Ratchet with a 5/8 Socket
Flat Screwdriver
Safety Glasses Gloves

Step 1- Remove the whole Hood Assembly Hood:

Most probably, what you need to do now is adjust the valves on your mower engine because overhead valves prevent the engine from working properly.

First, remove all the connecting bolts that hold the hood onto the body.

Then, you can remove the front end of your mower.

Tips: If you are good at such repairing tasks, you might be able to adjust the valves without even removing the hood.

This is the cover that needs to come off to adjust the valves.

Also, remember to put a piece of cardboard and rag under here because a little amount of oil will come out while removing the cover.

Now, use a 10-millimeter Socket and remove the four bolts.

Then, remove the cover by hand.

If you cannot, you can use a flat screwdriver to pry it off, and you can see it here by this silicone.

Step 2- Remove the Spark plug Check the Existing Gap between the Valves:

Next, you need to remove the spark plug, which is usually located right here on the riding or lawn mower.

Thus, use the 5/8 spark plug socket by removing the plug. It will be easier to turn the engine over by hand when adjusting the valves.

Here you can see the existing gap between the valves.

You can usually adjust these valves here with the rocker arm between three to four thousandth of an inch.

But the existing gap is much wider, and that’s the reason why it is so hard to turn over.

You can put a 17 thousandth-of-an-inch feeler blade here, but the gap is four times bigger than it should be.

Step 3- Adjusting the Top Valves in the Primary:

Turn the engine by hand until one valve is open and adjust the other. Then, continue repeating the same technique for all valves.

Now that you have opened or pushed in the valve, you need to adjust the top valve.

For this task, you will need a 10-millimeter wrench and a t25 Torx screwdriver.

Next, you need to hold the 10-millimeter nut and undo the Torx screw from the inside.

You need to adjust this at four-thousandths of an inch and have the feeler gauge ready to stick in between the valve as well as the rocker’s arm.

Now, if you want to close the gap, turn it clockwise with the 10 millimeters, not the wrench. You will notice that the feeler blade is getting tighter in there.

Basically, you should adjust it nice and snug in there, it shouldn’t be too loose or too tight.

Then, hold the nut and tighten up the Torque screw.

Step 4- Adjust the Other Valve on the Intake Cam:

First, turn the engine until the other valve is closed.

This one shown in the image is open.

Now, repeat the same procedure like setting the feeler gauge in and tightening up the 10-millimeter nut.

If you cannot turn the nut in deep enough, you should loosen the Torque screw again ahead and loosen that enough.

Now check the feeler blade in there whether it’s nice and snug or not.

Next, turn the engine over a few turns to recheck.

Step 5- Cleaning the Exterior Parts:

If it looks good as shown in the picture, all you need to do is clean the exterior part over where the gasket goes, and if there’s no gasket, they must have used the RTV silicone there.

In that case, you have to remove all the stuff before re-installing the cover.

So, ensure it’s all clean around the head because the engine will not cope properly when it is excessively dirty.

You can use 3m Scotch Brite pads on your die grinder to wipe off any excess oil.

It’s also a good idea to change the oil while you are working on it.

Now, use a Scotch Brite pad to clean the gasket surface area.

Next, spray the card cleaner to wash off the excess dirt and wipe them off properly.

Remember to get that excess oil out of here.

While you are cleaning the exterior areas, put the valve cover into soap and old fuel mixture to wash the dirt off.

Then use the Scotch Brite pad again and put it on the die grinder to dispose of the old fuel.

Step 6- Reinstall the Parts Test the Engine again:

This is the new gasket, which you are going to insert in there for the rocker cover.

First, remove the paper film from the new gasket and attach it carefully to the head.

However, you can also apply a small amount of RTV ultra black silicone on the cover before putting it back.

Now just reinstall the cover in its position and tighten up the screws securely.

If your mower spark plug looks severely damaged, install a new one before proceeding further.

Finally, restart the engine to test whether it’s working properly or still turns over only halfway

Performing such repairing tasks can be hazardous. Thus, make sure you have enough expertise to perform them. Remember to first read your mower’s instructions manual before operating, servicing, or troubleshooting it.

Frequently Asked Questions

How can you unstick your lawn mower engine?

Your lawn mower engine got seized up due to either contaminated engine oil or a defective spark plug. Thus, remove the spark plug to check it and drain the engine oil. Then, spray some penetrating oil into the cylinder and try cranking the motor manually. Next, add fresh engine oil and reinstall the spark plug or replace it with a new one.

Does a Crankshaft turn freely?

Yes, it can turn freely only if the crankshaft is mounted on the block without the heads or pistons attached.

Is it possible to turn the crankshaft pulley by hand?

Yes, you can. But you should attach a large socket on the crankshaft’s front bolt and remember to attach a long ratchet wrench too.

Is it possible to spin a lawn mower engine backward?

Yes, when you hit an immovable object, the mower engine will start spinning backward.

Can you turn a mower flywheel by hand?

Yes, you can and watch this video to learn the details process of doing so.

Final Verdict

Initially, the whole troubleshooting method might seem complicated, but if you thoroughly follow all the instructions described in today’s article, it will become much easier and quicker to finish the job.

Remember, you can only get the best outcome if you follow all the instructions to troubleshoot a Mower engine only turns halfway.


How to un seize a riding lawnmower engine

One may face many technical problems from time to time if he owns a riding lawnmower. A seized lawnmower engine is, however, one of the rarest of problems. If you do not want to take your Lawnmower to the mechanic because you fear that he might charge more, don’t worry. This blog will help you distinguish the damaged parts, replace them, and test them, all at a home scale.

Simple Fix on a Seized Hydrolocked Mower Engine #baldeagle242

A lawnmower engine is usually a sturdy component. A seized engine is usually due to the piston and rings sticking in the bore. With the help of some freeing fluid or cleaner, this problem can be solved. However, there might be other contributing factors to this too. Here we take you through them all.

How to un seize a riding lawnmower engine:

  • Step 1: Remove the spark plug
  • Step 2: Clean the combustion chamber with some cleaner
  • Step 3: Open the head and gently tap the piston cylinders
  • Step 4:Check the motor oil
  • Step 5: Test the blades and close all the components

We shall provide in-depth details of the steps mentioned above, like what sort of tools you need and any complexities you might face. Please stick with us as we go through all the potential issues and troubleshoot each of them.

Steps to Un Seize a Riding Lawn Mower Engine:

A riding lawnmower engine may get seized after you de-winterize it due to such distant usage. The seized engine may be due to the parts that are stuck or due to the machine’s absence of motor oil. The procedure below explains all the necessary steps to deal with the situation.

Step 1: Remove the spark plug:

Whenever a defect occurs related to the internal parts of a lawnmower, removing the spark plug is the first step. The spark plug is removed before cleaning the rest of the parts for two purposes. One is so that no accident occurs when one is pulling and cleaning the cord. The second is to clean the spark plug itself.

To do this, tilt the lawnmower body to a side so that its side now faces the roof. With the help of a plier, unscrew the spark plug because it may be hard to remove it by hand (seized up chamber). Now, using a feeler gauge, you may check the gap between the spark plug terminals. Compare it with manual reading. Now, either clean the plug or replace it.

Step 2: Clean the combustion chamber with some cleaner:

Through the removed spark plug hole, you can access the piston cylinders and the combustion chamber. You can quickly get aerosol sprays like “Blaster PB” or “WD-40” from a local hardware store. When you buy them, do get yourself a pair of safety gloves as these might be toxic to spray, hence injurious to health. Now, through the hole, flood in an available amount of the cleaner spray and let it rest there for a couple of hours at the least.

The cleaner spray acts as an anti-rust and lubricating agent. It removes the clog built up in the chamber. After a few hours, let the cleaner fluid drain out from the spark plug hole. Now, try to move the blades manually. Make sure that while rotating them, they should be rotated in their natural directions. You will feel lesser resistance to the movement now.

An additional step can be to pull the cord and see the blade’s rotation. This may further give some idea about the extent of seizing in the engine. Pulling the card will produce little motion in the lawnmower blades, a sign for a seized up engine.

Step 3: Open the head and gently tap the piston cylinders:

Sometimes, only using a cleaner doesn’t solve all of the problems as the riding Lawnmower may have been idle for a longer time. In this case, remove the seat to expose the head of the engine. Opening the head with a screwdriver or wrench will allow you actually to see the piston cylinders. The engine may be blocked and may require an internal push start.

So, hit the piston head preferably with a wooden hammer. Tap it gently as it moves down. This pretty much solves the problem. Besides, check the piston rings, lubricate them. Check for any damaged seals, take no risk, and replace them. Clean the cylinders and remove any dirt or debris that has hardened up and is stuck. Throw in some cleaner spray to moisten the dirt and clogged up the oil. Clean it and let it dry for a few hours.

Step 4: Check the motor oil:

We have already taken you through the basics. These were easy to solve. Now, a more complex issue that may require more of your FOCUS is here. In all types of seized activities, the one that is caused by running the engine on an insufficient motor oil spray is the most serious.

Through the removed piston head, disintegrate the crankshaft. Same as before, using a wooden hammer, give the cylinders a strike to thump them out. Also, rotate the crank. This helps remove the crude oil that got stuck up in the moving parts. Use a cleaner to purify them thoroughly.

Remove the connecting rods and seals. Clean them too, as crude oil may still be stuck there. Give the insides a thorough washing. You can use petrol to wash it too. Now, let the engine bask in the sun and dry up naturally. Add lubrication to each component as you close up the casing and side by side, give the lawnmower blades a gentle thrust to make them move.

Step 5: Close all the components:

After all this day long hustle, most of your technical work is done. However, closing all the components is the essential key for prolonged safety from damage. After all the parts have been lubricated and dried up, conceal them as they were taken out. Ensure the seals are tight, the crankshaft is fixed, and piston cylinders are’ t free. Close the head and fix the seat back in its place. Add new motor oil to your Lawnmower. Remove the old crude fuel. Add new fresh fuel, preferably with some anti-clogging agents mixed in. For a week on, use the mower gently and regularly so that engine gets back to its full potential.

Even if, after all these steps, the blades aren’t softening up as much as they should, it is time to call in an expert.

Related Questions:

1) Why should I use a wooden hammer or wood to strike the piston cylinders?

The combustion chambers are quite sensitive parts in terms of dimensions and sensitivities of pressure, are, and volume. A regular hammer, if used to thump the cylinder, may cause the cylinder to disorientate. At the very least, it can cause a dent in the cylinder or piston due to its rigid nature. Deformities can cause a change in the critical pressure or volume of rotating machines, which can be very dangerous.

A wooden hammer, on the other hand, is rigid and flexible at the same time. You may have observed that all denters use a wooden hammer to remove the dents too. This allows them to give a considerable power strike keeping the flexibility and geometry intact.

2) How can you tell if your lawnmower engine is seized?

To tell if a lawnmower engine is seized, you have to follow through a few steps. Start by removing out the spark plug to expose the channel to the combustion chamber. If a lawnmower with a removed spark plug still jump-starts, its valves may be worn out and hence, need replacement. However, if the engine doesn’t run and the blades are rigid and don’t turn over, it is seized. A seized lawnmower engine has locked cylinders, blades, and pistons.

3) Why removing the spark plug is necessary?

When operating on a riding lawnmower with sharp blades, precaution is a must. While cleaning, one has to clean the combustion chambers, piston cylinders, and valves. Sometimes, even the cord needs maintenance, so it has to be pulled. So, as a safety measure, it is advisable to remove the spark plug before any Lawnmower action to keep away from any harm.

Final Remarks:

For those who love their hobby of gardening, a lawnmower is the best buddy one must-have. However, after long gaps or after de-winterization, its use may pose some problems in engine activity seizing up. A seized engine doesn’t mean the machine’s death, but it sure affects its life if not addressed. Following the steps mentioned above in definite order, you can efficiently deal with this issue. It may seem huge at first glance, but following the guide will help you step by step. Even after all these steps, your Lawnmower fails to work correctly, and it is better to take it to a mechanic. Happy lawnmowing!

Small Engine Pull Cord Stuck: Why and What to Do

I have run into issues with the pull cord being stuck on my gas-powered yard tools quite a few times over the years. While this can definitely be an annoyance, it’s a relatively easy fix once you have located the problem. But why does the pull cord get stuck in the first place?

If you find that your pull cord is stuck, there are a few factors that could be causing this. For one, a build-up of grass or debris may need to be removed in order for the pull cord to move again. You may also have an issue with your recoil starter, which could be damaged.

In this article, we’ll be going in-depth into why your small engine pull cord gets stuck, how this happens, and how you can fix it yourself. If you’re interested in learning more about these topics, keep on reading.

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Why Does My Pull Cord Get Stuck?

There are a few factors that may be responsible for your pull cord becoming stuck. While this can be an annoyance to those who can’t figure out why their equipment has stopped working, it’s a pretty easy fix once you find the problem.

Below, we’ll go in-depth into some of the reasons your pull cord has become stuck and how you can fix this in just a few easy steps.

Grass and Debris Is in the Way

This is a common problem that many lawn mower owners face, and thankfully it’s a pretty quick fix. Grass and debris can build up over time and can prevent the blade from turning. The blade is connected to the starter coil, so if the blade is unable to move, your pull cord will be stalled as well.

If your pull cord moves slightly, it’s likely that there are grass and debris that needs to be removed from the housing on the top of the motor. You can simply unscrew the top of the housing yourself and have a look around to see if this is the cause of your problem.

Once you’ve successfully removed the housing from your motor, remove the debris safely by using a screwdriver. Examine the areas surrounding the cord and the pulley disc for anything that may be hindering your machinery.

Problem With the Automatic Break

If you’ve examined your equipment for debris and you weren’t able to find anything, try checking the automatic brake. If you feel a lot more resistance when trying to move your pull cord, it’s likely an issue with your brake.

Many different types of lawnmowers have this kind of lever that will automatically stop your engine. In order to get your machine moving again, you’ll have to manually depress this lever and hold it down before pulling your starter cord.

This is another common occurrence that can easily be fixed by just following a few quick steps. If you feel if this is the problem with your pull cord, just simply depress this lever to get your machine up and running again.

Problem With the Recoil Starter

While the slight movement of your pull cord means there is likely debris where there shouldn’t be, no movement at all is a sign of a damaged recoil starter. Your pull cord can sometimes cross over itself when it’s rewinding, causing your cord to become easily stuck.

While your pull cord may be simply tangled, it may also become damaged in the process and may need to be replaced. Upon further inspection of the area, you should be able to tell if you simply need to loosen the tangle or replace anything that’s been broken or displaced along the way.

If you feel as if your pull cord has become tangled, remove the housing of your motor, rewind the rope to inspect if it is tangled or damaged in any way. If it’s tangled, you’ll want to reset the spring, or remove it and install a new one.

In the video below, you can get a visual step by step, looking into how you can successfully fix the issue you’re having with your pull cord when the recoil starter is the main issue:

Thriving Yard aims to simplify the unnecessarily complex process of growing and maintaining a healthy, thriving lawn and garden. Unlike corporate website companies who write articles from an office overlooking a major city, the authors on this website live in small towns and regularly use many of the tips and recommendations provided in their own garden and lawn care. Read

White Smoke From Lawn Mower – Easy Fix!

White Smoke from your mower looks pretty serious, but usually, it’s a simple fix.

A mower commonly blows white smoke for two reasons:

  • Mower tipped over incorrectly
  • Engine overfilled it with oil

Other possible causes include:

Mower tipped over is the most common reason for white smoke. Usually, the customer turns over the mower to clean the deck or unclog the chute. This allows oil to enter the cylinder, and when the mower is restarted, the oil burns and turns your yard into a 70s disco. Sometimes oil will also leak from the muffler.

The fix is simple, check the mower for oil and let the engine idle until the smoke clears. If your lawnmower is a tractor mower, white smoke usually means too much oil, a carburetor fault, or a blown head gasket. (more on this below)

The diagnosis and fix are covered here in this post, but if you need video help, check out the Mower blowing white smoke video. It walks you through the process step by step – diagnosing, oil removal, carb check repair, and compression testing for a blown head gasket; it’s all covered.

Tipping the mower on its side for maintenance or cleaning causes oil to move into the cylinder.

When you fire up the mower, the oil in the cylinder burns to cause white smoke. It will clear after a short while.

I hook the handlebars under a bench. Turing your mower to the side is fine as long as you turn it with the air filter side up.

Turn the air filter side up for greater access and avoid the white smoke.

A Case Of Too Much Oil

Lawnmower engines usually take a little over half a quart (.6lt), so it’s easy to overfill them. Lots of my customers add oil without ever checking the level. They do this thinking it won’t do the engine any harm.

Wrong! Too much oil can damage the engine, as most operate a splash lubrication system. When the oil level is above the splash paddles, they don’t work efficiently.

Don’t damage your engine needlessly. I wrote the complete guide – which shows you how to dip your oil, oil types, quantity, and how to drain oil; you can check it out here How to check oil level.

The white smoke is the engine burning off all the excess oil. The fix – drain the excessive oil, and idle the engine until the smoke clears. This may take 5 minutes or so.

Depending on your mower type, draining the oil can be a pain in the ass. I got this Briggs and Stratton oil extractor on Amazon; it makes life soooo easy. You can check it out here on the “Small engine repair tools page”

Too much oil will cause other problems, smoke, poor running, no running, leaks, and engine damage. Check out “How to check oil level”.

Drain excess oil and check and top up if needed.

Gas In The Oil

If your oil level is overfull and smells of gas, it’s likely you have a failed carburetor seal. Don’t run the engine, as the oil is too thin and offers no protection. Change the oil after making repairs to the carburetor.

If you think this sounds like your problem, go ahead and replace the carburetor, it’s faulty. I wrote this complete guide to help you check your “Carburetor troubleshooting”.

You may prefer a step-by-step video guide on carburetor cleaning; it includes removing, stripping, cleaning, rebuilding, and refitting your carburetor.

Carb cleaning is included in the video library of common lawn mower problems; all guides are easy to follow.

Carb cleaning is covered in this guide titled “Mower engine surging.” It’s so-called because surging and stalling are common symptoms of a dirty, faulty, or contaminated carburetor.

You may also need a tune-up; I wrote an easy-to-follow “Lawn mower tune-up” guide, including pictures and a maintenance chart.

The oil level will be overfull and stink of gas.

The fix is to replace the float needle and seal or replace the whole carburetor. Consider fitting a fuel tap, and don’t forget to change the oil.

White Smoke Dies

This is a sure sign that oil has made its way into the carburetor and is blocking the gas feed jet. Most times, repeated starting and running of the engine will clear the oil. However, if you cannot run the engine long enough, you may need to clean the carburetor.

First, try removing the plug and turning over the engine a few times to expel oil from the cylinder. Clean or replace the plug and try starting again. If this fails, you can check out “Carburetor Cleaning,” where I show you how to remove and clean your carburetor.

Remove the plug and clear the cylinder by turning over the engine with the pull cord. Clean the plug before refitting.

Oil In The Gas Tank

In addition to overfilling with oil and tipping the mower on its side, putting oil into the gas tank accidentally is very common. Using the trimmer 2-cycle mix in the mower gas tank is a common mistake, too; it won’t produce the dramatic white smoke like engine oil though.

The fix – drain the gas tank and, refill it with fresh gas, run the engine to clear the system. If the engine fails to start, no problem, check out my guide – “Carburetor cleaning.”

Head Gasket Failure

A failed head gasket is much less likely but will produce lots of smoke. Unlike previous solutions, it’s a little more work. A head gasket is a metal and graphite material.

It’s fitted between the cylinder block and the cylinder head of an engine. Its job is to seal the combustion chamber.

High crankcase pressures and oil leaks are a sign of head gasket failure; you may also hear a slight puffing noise as compression escapes from the cylinder. The fix – replace the head gasket.

How to Fix a Seized Engine on a Lawnmower

A blocked crankcase breather will cause the oil in the cylinder and white smoke; clearing the breather pipe is a simple fix.

Failed or worn piston rings are the end; sadly, a rebuild is needed. A new engine is most likely a cheaper option and comes with a guarantee, but a new mower might make more sense at this stage.

Head gasket failure can cause white smoke. This will only be an issue with OHV (overhead valve) type engines and will also depend on where the gasket fails.

OHV engines are usually well marked with OHV on the front engine cover. When it fails, and depending on where it fails, it will suck oil into the cylinder and blow gases into the crankcase.

Last on the list is engine wear or ring damage. A compression test will confirm if you have internal damage. This condition is rare. Check out the “Compression test video” here.

Related Questions

Why is my electric lawn mower smoking? If your electric lawn mower is smoking, you must unplug it before attempting any further investigation. The motor has most likely burnt out. If, on the other hand, your electric mower uses a belt to drive the blade, it’s possible that just the belt is causing the smoke.

Does the lawnmower smoke on startup? This is generally associated with an old mower; it’s a sign of engine wear. But other possible causes include:

Hey, I’m John, and I’m a Red Seal Qualified Service Technician with over twenty-five years experience.

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