How To Check Compression On A Lawn Mower Engine (5 Easy Steps)

An internal combustion engine like in your lawnmower needs three things to run. It needs an adequate fuel supply, it needs an adequate spark, and it needs adequate compression. So you must be thinking why do you need How To Check Compression On A Lawn Mower Engine? Well, that’s a good question.

In a problematic compressor, the sparkplug might be a little bit blackened and a little bit fouled. The most likely cause of this is over-fuelling or rich fuelling. So a machine like a lawnmower sees such dirty services and has a kind of crude air filtration. 

So you’re going to face problems with that. Another possibility of this problem can be oil seeping past the rings on the compression piston and getting up into the combustion chamber and fouling it. So that’s when you need to know how to check compression on a lawnmower engine to be able to find out the problem and the solution. 

What Is A Compression Test?

A compression test tests “How To Check Compression On A Lawn Mower Engine”‘ well all the compressions are sealing. So typically on a small engine like a lawnmower, you have two valves; an intake valve and an exhaust valve and they have a seat. That seat can get carbon buildup on it, it can get burned, and that will prevent it from sealing when the valve closes. 

It’s not fully sealing, it’s allowing air in combustion to escape past the seat. Also, you’ve got a piston which got rings all down the side called compression rings and they are perfectly machined to seal the cylinder that the piston travels up and down in. 

So when these rings go bad you lose the ability to compress and draw in air. Because that seal has been lost. It’s not sucking air in and it’s not able to compress it. So that’s when you need to do a compression test on your lawnmower regularly. 

How To Check Compression On A Lawn Mower Engine | 5 Easy Steps

To detect the areal problem what you’ll do is a quick compression test and have a look and see what kind of numbers you’re pulling. So let’s discuss the step-by-step process of how you can do that. 

How To Check Compression On A Lawn Mower Engine

Step 1

There are three really quick things we have to do here before we check the compression we’re going to explain to you. The first one, you know that little bail handles that when you start your lawn mower you got to pull that bail handle down. You got to tie that down. You can use a clamp or a rope to tie that down. 

So what that did is just release the brake on the flywheel so the engine can actually spin around and also turned on your on-off switch. Now pull the spark plug boot off of your spark plug. So there’s no chance that this thing can start. 

Step 2

Now it’s time to flip your lawnmower over. If you flip your lawnmower over-identify where your air filter is. If you flip your lawnmower the other way so your air filter and the carburetor are on the downside. Engine oil is going to pour out of there. It’s going to destroy your air filter and you’re going to have a big puddle of engine oil on the floor when you’re done. 

So flip your lawnmower over so the air filter is always on the upside. That’s how you want to flip it. Now make sure you’re wearing leather gloves before you’re doing all this for safety. So flip your lawnmower and look at that blade. 

Step 3

To check out the compression you need to spin the blade around always in the direction that it’s supposed to go. So look at the Sharpe side and it needs to go forward. So that’s the way you want to spin this thing. 

Spin it with your hand. If it bounces that blade backward that is really good compression. You guys are going to find sometimes that you don’t have the blade bouncing backward; you might find that it comes to a squishy stop where you spin it and it does not bounce backward. It just stops in the middle. 

Step 4

It does not keep going around and around but it stops. If it does that then you have to understand that you might have some compression in there but it’s not good compression. It may or may not be enough compression for your engine to run which is called mediocre compression. 

So then you have to understand that there could be something wrong with your engine there too if it just comes to that kind f a dead stop but doesn’t bounce backward. 

Step 5 

The worst-case scenario here might be like this when you try to rotate the blade it just goes round and round but never stops. That means you have zero compression. There is no compression on that thing at all. So there is no possible way that that engine can run with a lack of compression like that.


How To Check Engine Compression Without A Gauge

It is possible to check engine compression without a gauge, although it is not as accurate as using a gauge. One way to do this is to remove the spark plug and insert a small screwdriver into the hole.

Turn the engine over slowly and see how far the screwdriver is pushed in by the compression. Another way is to remove the oil dipstick and insert a long screwdriver into the hole. Again, turn the engine over slowly and see how far the screwdriver is pushed in by the compression.

How many compressions Should A Lawnmower Have?

Lawnmower compression is important for several reasons. First, it helps the engine start more easily. Second, it gives the engine more power. Third, it reduces fuel consumption. Fourth, it increases the life of the engine.

There are several factors to consider when setting lawnmower compression. First, consider the type of engine. Second, consider the age of the engine. Third, consider the size of the engine. Fourth, consider the operating conditions.

For most lawnmowers, a compression ratio of between 6:1 and 8:1 is ideal. This provides enough compression to start the engine easily and provides plenty of power. It also reduces fuel consumption and increases the life of the engine.

If you have an older engine or one that is not in good condition, you may want to increase the compression ratio. This will help the engine start more easily and give it more power. However, it will also increase fuel consumption and wear on the engine.

If you have a newer engine or one that is in good condition, you may want to decrease the compression ratio. This will reduce fuel consumption and wear on the engine. However, it may make the engine harder to start.

The best way to determine the ideal compression ratio for your lawnmower is to consult the owner’s manual. If you don’t have the manual, you can usually find the information online.

How Do You Check The Compression On A Briggs And Stratton Engine?

Briggs and Stratton’s engines are known for their durability and reliability. However, like all engines, they will eventually need some maintenance. One important thing to check periodically is the compression.

Compression is what gives the engine its power. When the piston goes down, it draws in air and fuel. When the piston comes up, the air and fuel are compressed. This compression is what ignites the spark plug and makes the engine run.

Over time, the compression in a Briggs and Stratton engine can decrease. This can be caused by a variety of factors, including normal wear and tear, as well as carbon buildup on the piston and cylinder walls.

When checking the compression, you will need a compression gauge. This attaches to the spark plug hole and measures the amount of pressure in the cylinder. Ideally, you want the reading to be between 125 and 175 psi. If it is lower than that, it indicates that the engine is not getting enough power and will need to be serviced.

To check the compression, first, make sure the engine is cool. Then, remove the spark plug and attach the compression gauge. Pull the cord to turn the engine over a few times. The gauge will give you a reading.

If the compression is low, there are a few things you can try before taking it to a mechanic. First, check the spark plug. If it is fouled, clean or replace it. You can also try using a higher octane fuel. If neither of these things works, then you will need to take the engine to a mechanic for further diagnosis.

How Do I Fix The Compression On My Lawn Mower?

Your lawn mower’s compression is an important part of the engine, and if it’s not working properly, your lawn mower won’t run. There are a few things you can do to fix compression on your lawn mower.

First, check the spark plug. If the spark plug is fouled or damaged, it can cause compression problems. Clean or replace the spark plug as needed.

Next, check the air filter. A dirty air filter can restrict airflow and cause compression problems. Clean or replace the air filter as needed.

Finally, check the engine for leaks. Leaks in the engine can cause loss of compression. Inspect the engine carefully and repair any leaks that are found.

following these steps should fix the compression on your lawn mower. If you’re still having problems, take the lawn mower to a qualified repair shop.

What Causes A Lawn Mower To Lose Compression?

A lawn mower can lose compression for a number of reasons, including a loss of spark, a dirty air filter, or a problem with the carburetor. When a lawn mower loses compression, it can be difficult to start and may run rough.

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Final Verdict

So we hope now you know How To Check Compression On A Lawn Mower Engine if you are professional this should be one of your routine checkups. Because you know how problematic it can be if your compression has any defect. You can also use a compressor tester but the result will not be that credible. 

I'm Jimmy, the creative mind behind Drawing from extensive expertise in home improvement, I founded this platform to help individuals transform their living spaces. My dedication lies in empowering homeowners with dependable advice, ensuring that every DIY project not only elevates your home but also enhances your lifestyle. Join me as we redefine homes, one project at a time.

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