5 Major Lawn Mower Valve Adjustment Symptoms That You Can’t Ignore

lawn mower valve adjustment symptoms

To keep an eye on the major lawn mower valve adjustment symptoms are necessary because, in any mechanical equipment, including lawnmowers, clearances, gaps, or valve adjustments are always essential parts that need little adjustments while being used, maintained, or repaired.

Valves are the key to your lawnmower’s performance. They control what goes into and comes out of both intake valves, as well as Exhaust Valves; they also have clearances that need a regular inspection for any damages or wear-and-tear before it jams up inside their mechanism!

We all know that maintaining a healthy and well-maintained lawn is essential for the upkeep of your property, but did you also realize just how important it can be?

A bad valve could result in a lack of water at times when needed most. This leaves patches brown and withered while others struggle with greening up properly because they’re receiving too much sun exposure!

In order to prevent any future problems like these from happening we’ve put together this guide on noticing adjustment symptoms as well as for instructions about what needs adjusted based on their type so now there won’t ever again need to spend hours scouring the internet trying to find out why something isn’t working correctly.

Consequences of Poor Valve Adjustment

Maintenance is the key to a healthy and happy lawnmower. The efficiency and performance of your lawnmower rely on the care you take with its intake/exhaust valves. Without regular maintenance, your mowing sessions may be harmful not just for you but also to those around you who could end up getting exposed if something isn’t done about it quickly enough! It can cause:

  • Rough idle engine running.
  • Alignment and balancing issues.
  • It can decrease the power and mileage.
  • It can cause extreme heat damage to the engine.
  • It can entirely damage the other valves.

Major Lawn Mower Valve Adjustment Symptoms

The valve gap changes with time and usage. However, it’s not the main cause behind these changes that are caused by maintenance issues like neglect or over-filling of your tire which could lead to more serious problems down the line if left unchecked for too long!

If you see any other symptoms during the mowing session then there might be an issue at hand so make sure never ignore them as this will only get worse later after regular tuning has been done without solving anything initially.

If your engine generates a loud tapping noise, or you are noticing some power loss in your lawnmower, then these are the signs of valves adjustment point.

Let’s look at the top 5  lawn mower valve adjustment symptoms.

The major lawn mower valve adjustment symptoms can include:

  1. Hard to pull the starter cord.
  2. Hard starting.
  3. No Compression.
  4. Power loss with excessive fuel consumption.
  5. Noisy engine with rough running.

Let’s take a brief look at these symptoms.

1. Hard to Pull the Starter Cord – Major lawn mower valve adjustment symptoms

One of the most common symptoms that indicate a need for valve adjustment is when your lawn mower’s starter cord becomes hard to pull. This can be an indication not only in one area but across many parts, so it might just save you some time if we look at them all together!

The cord becomes hard because of:

  • Excessive cylinder compression.
  • An increase in the valve gap.

Advance engines have compression release technology to open the valves early to release the compression of the engine and the cylinder.

2. Hard Starting

When the valve gaps are entirely misaligned, then it can cause a hard start engine.

Hard starting is a common problem with engines. If you notice that your car has been performing poorly and often fails to start, there could be an issue at either the carburetor or battery terminal where power coils are connected (or both).

Hard starting further harms the head gasket.

Lawn Mower Valve Adjustment Symptoms

3. No Compression or Starting Issues

When the entire mechanism behind the valve movement becomes damaged, stuck, or misaligned, it causes starting issues, and the engine begins missing while starting.

Stuck valves are the result of lacking compression. You can fix the stuck valves by using a screwdriver to provide compression to the spring.

You can perform a compression test to check your engine life.

4. Power Loss with Excessive Fuel Consumption

Increased or decreased tappets can adversely affect the efficiency of the lawnmower by affecting its power. The lawnmower starts consuming more fuel or gas without providing proficient results.

It needs an adjustment to keep your lawnmower running and durable for a long time.

5. Noisy Engine with Rough Running

You can also hear a tapping noise along with the power loss and excessive fuel usage because of an increase in the valve gap. Ignorance will lead the engine to permanent wear out.

When the inlet and exhaust valves are not supporting the engine to perform correctly, then the engine becomes off-balance and rough day by day, both in performance and sound.

Adjust the valves by using a feeler gauge and a wrench to help the engine in proper breathing to gain power while consuming less fuel.

Why the Valve Adjustment is Important

Valve adjustment is vital to be maintained because:

  • It can provide space for thermal expansion.
  • It ensures the positive closing of the valves through spring support.
  • Precise adjustment of valves provides the proper opening and closing times of valves.
  • It improves engine mileage and performance.
  • Poor valve adjustment affects fuel consumption.

In most engines, the function of rocker arms is to open and shuts the inlet and outlet valves of the engine. The Rocker arm and valve head are not directly linked or connected.

Lawn Mower Valve Adjustment

Increasing and decreasing the adjustments directly affects the opening and closing timing of inlet and outlet valves.

  • Insufficient tappet causes early opening with late shutting to the valves of the engine.
  • Extra tappet becomes the reason for the late opening and early closing of the valves.

Mostly, the general tappets, gaps, or valves adjustments range from 0.30mm to 1.5mm depending on air and exhaust valve manufacturing.

Also Read: How to Start a Riding Lawn Mower with a Screwdriver

How to Adjust Valve Gaps – Fixing Major Lawn Mower Valve Adjustment Symptoms

Once you know whether the tappets or the gaps are less or more, then it will be easy for you to increase or decrease them.

Lawnmower Valve Adjstment

Although, the valve adjustment is a quite tricky and skillful session. But you can follow the mentioned steps to check out the valve adjustment:


  • Remove the plug and turn off the fuel connection.
  • While using a rag, remove the rocker cover.
  • The rocker cover has a gasket. You can reuse or replace it according to the need.
  • Rotate the engine by keeping an eye on both the valve and the compressing turns.
  • By using turning blades, rotate the engine and keep noticing that the compression of valve springs.
  • Make sure the straightness of the pushrods, otherwise make a replacement to avoid no start condition.
  • Never try to remove pushrods for valve adjustments.
  • Locate the intake and the exhaust valves.
  • Rotate the engine clockwise by turning the blades.

Steps to Fix the Major Lawn Mower Valve Adjustment Symptoms

  • Keep turning the blades and rotating the engine until the intake valve becomes open and fully compressed.
  • Insert a round and unsharpened object into the plug hole against the piston. Rotate it clockwise again and keep noticing the point when the round object is pushed out by the piston. When fully out, this is the Top Dead Center (TDC).
  • Unloaded the valve springs by keep turning the object into the cylinder.
  • It is the Power stroke point where the valve adjustment begins.
  • The exhaust valve tappet increases with the heat. Valve clearances vary from model to model. Observe the valve gap, according to the manufacturer.
  • Move the feeler gauge blade between the rocker arm and valve head to observe the resistance.
  • Make sure the smooth movement of the feeler gauge between the valve head and the rocker arm to get a perfect valve adjustment; the gauge may not be too tight and also not very loose, i.e., between 0.30mm to 1.5mm.
Lawnmower Valve Adjustment Symptoms
  • After getting a perfect valve adjustment, tighten the nut with the given torque.
  • Keep the record for future adjustments.

Engine noise elimination is not only the benefit that is the result of properly adjusted valves, but the engine will also become efficient, smoother, and more responsive.

Moreover, proper adjustment can make the engine and the valves durable and efficient for a long time.

Always look out for lawn mower valve adjustment symptoms and take timely decisions to fix them. We hope this article will help you in observing, diagnosing the symptoms, and adjusting the valve gaps of your lawnmower on time.

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