Lawn Mower Valve Adjustment Symptoms: Top 5 and How To Fix Them

A decline in the engine’s performance is one of the lawn mower valve adjustment symptoms. –Avoid these mower brands.

Poor valve adjustment causes serious harm to the mower in the long run since the valves play a vital role in determining the engine efficiency.

The shaft inside the engine lifts the valves at varying intervals allowing air into the engine and let out the gas.

Once the valves lose their right timing, you will notice a drop in the lawn mower’s performance.

For you to correct this, you have to adjust the valves.

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This article has listed some of the common lawn mower valve adjustment symptoms and how to fix them.

Common Lawn Mower Valve Adjustment Symptoms

The efficiency of any lawn mower highly depends on good maintenance of exhaust valves.

Poor valve adjustments can cause damages to the mower leading to the engine losing power.

Below are some of the lawn mower valve adjustment symptoms.

1. Noisy Engine

Whenever the mower is on, you may hear a tapping noise due to the increased valve gap.

This indicates that the valves do not support the engine properly, eventually resulting in engine power loss.

Eventually, the engine will start being off-balance, reducing its performance.

lawn mower valve adjustment symptoms

2. Hard Starting

Hard starting occurs when the valves are misaligned, meaning that there is an increased valve gap.

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This defect ends up affecting the whole mechanism of the valve movement, which further affects lawn mower’s functioning.

Hard stating eventually cause damage to the head gasket.

3. Hard To Pull Starter Cord

This is the most common symptom of lawn mower valve adjustment symptoms.

The cord may become hard to pull due to excessive cylinder compression and increased valve gap.

Its engine becomes too hard to start leading to inconveniences.

Some advanced engines feature a compression release technology that opens valves earlier, releasing engine and cylinder compression.

4. Power loss with excess fuel consumption

Reduced or increased tappets make the lawn mower consume more gas while performing poorly.

This affects the efficiency of the mower to its reduced performance in the long run.

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It also leads to losses due to the increased fuel consumption with reduced output.

No compression

Whenever the valve movement mechanism is not right, it results in starting issues since the mower engine starts missing when starting.

Stuck valves are a sign of lack of compression, and you can use a screwdriver to add compression to the spring.

Results of Poor Lawn Mower Valve Adjustment Symptoms

Since a lawn mower’s performance and efficiency majorly depend on the intake and outtake valves, it’s essential to have a good maintenance plan.

Whenever the valves are faulty, they may damage the lawn mower, making you incur more repair costs.

Some of the other consequences of poor valve adjustment include; increased heat that leads to engine damage, Rough engine running, Damage to the rest of the valves, and Alignment and balancing issues.

Importance of lawn mower valve adjustment

It ensures that the valves in the right way through spring support and also gives space for thermal expansion.

Since poor valve adjustment leads to increased fuel consumption, adjusting them saves you more on fuel.

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It provides the right opening and closing time intervals of valves and, lastly, improves the engine’s life and performance.

Since extra tappets lead to early opening and late closing of the valves.

Lawn Mower Valve Adjustment Symptoms (2)_1_1

How to fix Lawn Mower Adjustment Symptoms

Before you start fixing your lawn mower’s adjustment symptoms, the first thing to do is determine whether the gaps are more or less.

Step 1

Remove the bolts securing the valve cover on top of the engine then place it aside.

In order to keep the intake valves open and compressed, ensure you keep the engine rotating and lawn mower blades turning. Don’t remove the push rods when adjusting the valve

Step 2

Remove the spark plug wire using a spark plug socket and ratchet.

Rotate the engine in a clockwise direction by turning the blades.

Step 3

Place your screwdriver in the spark plug hole until you feel its tip pressing against the top of the piston.

Carefully rotate the shaft extending it from the bottom of the engine.

At this point, you will feel the piston pushing up on the screwdriver while rotating the shaft.

Once you feel the direction shift and your screwdriver starts going back down, start rotating the shaft in the opposite direction until the screwdriver starts going back up.

This point is known as the Top Dead Center (TDC).

Step 4

Try locating the rocker arm that is above the exhaust valve.

The exhaust valve is usually located at the muffler on the engine.

The valve gap varies from one model to another, so observe it depending on the manufacturer.

Step 5

Use the screwdriver to increase or decrease the gap between the top of the valve and setscrew.

Tighten the jam nut then use a feeler gauge to test the gap by placing it between the top of the valve and rocker arm.

Ensure you use the given torque after getting the right valve adjustments to tighten the jam nut.

Repeat this up to when you will get a slight drag with the feeler gauge.

Step 6

Repeat step five this time with the intake valve positioned near the carburetor on the engine.

This time replace the 0.005-inch feeler gauge with a 0.003 feeler gauge.

The indicator should not be too tight or too loose.

Step 7

Keep the record for use in future adjustments.

Replace the old valve cover gasket onto the engine top.

Final Thoughts on Lawn Mower Valve Adjustment Symptoms

Adjusting lawn mower valves makes the engine effective and responsive and eliminates noise to give you quiet operation.

The adjustment also makes the engine more durable, saving you money of replacing it more often.

Always be keen to observe lawn mower valve adjustment symptoms as early as possible to avoid further damages.

I hope this article has given you some tips on identifying the symptoms and adjusting the lawnmowers valve gaps as early as possible.

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