What Causes A Blown Head Gasket On A Lawn Mower? [With Tips On Repair]

The head gasket is one of the most critical parts of your lawnmower. It won't work correctly or with its full power if it blows. So, what can be the causes of a blown head gasket on a lawn mower? We've done some research, and here's what we've found.

Your lawnmower's head gasket can blow due to several reasons. These significant reasons are:

  1. Overheating
  2. Bad gas
  3. Low oil
  4. Wrong or advanced combustion/ignition timing
  5. Improperly placed head gasket
  6. Wear and tear
  7. Engine Knock

Now that you know why a lawn mower head gasket blows, let's also talk about lawnmowers. We've included the signs and results of a blown head gasket and how you can replace it. You can also find several tools and materials for lawnmower maintenance and care.

Turning on the lawn mower by gardener, What Causes A Blown Head Gasket On A Lawn Mower [With Tips On Repair]

Why Lawn Mower Head Gasket Blows?

Like an automobile, a lawnmower also has a head gasket which is vital in locking the machine's combustion chamber to retain the motor's power. It's essential to check the condition of the head gasket so the lawnmower will perform at its fullest. Although sometimes, things happen, such as a blown head gasket. There are several reasons why this happens, and these are:

engine repair. cylinder head gasket replacement in the workshop


Your lawnmower can overheat because of low coolant, low engine oil, and clogged air cleaners. These can damage and result in a blown head gasket.

Bad Gas

Harmful gas can cause engine damage or a blown head gasket. Bad gas is referred to as dangerous fuel that won't ignite accurately.

Low Oil

Your lawnmower's oil plays a significant role in keeping an excellent engine. If you don't check the oil and it's low, the engine will run hotter and can cause a blown head gasket.

Wrong or Advanced Combustion/Ignition Timing

If you have a wrong or super advanced combustion timing, it can cause the fuel-air combination to kindle prematurely. An incorrect ignition timing can cause a hefty dose of heat and, yes, can blow the head gasket.

Improperly Placed Head Gasket

An improperly installed head gasket won't secure a compact seal between the cylinder head and the engine block. It can lead to a blown head gasket or similar symptoms.

Wear And Tear And Low-Quality Parts

Wear and tear and using low-quality parts are other causes of a blown head gasket. You can avoid these by buying a high-quality or branded lawnmower. You can also avoid it by practicing good maintenance.

Engine Knock

An engine knock happens because of several reasons, such:

  • Engine oil that's below the level
  • The rotor touches the carbon residues in the ignition chamber
  • Oil with a stability measurement that's too insufficient for your engine

Check for these causes to avoid engine knocking, and prevent your lawnmower's head gasket from blowing.

What Are The Indicators Of A Blown Lawn Mower Head Gasket?

Worker guy shake pour grass from lawn mower bag into wheelbarrow. Garden meadow lawn cutting. Summer works in garden. Static shot.

If your lawnmower encounters a blown head gasket, you may detect these signs:

  1. Inadequate power and pressure
  2. Unsuccessful condensation test
  3. Reduced contraction
  4. Fuel spreading and leaking
  5. A cloud of white or bluish smoke comes out from the tailpipe

How To Check For A Blown Lawn Mower Head Gasket

You can follow these simple steps in checking for a blown head gasket on your lawnmower.

  1. Check for known symptoms like an oil leak or white or blue smoke.
  2. Open the engine's cover.
  3. Dismantle the engine's filters, dipstick, and carburetor.
  4. Find and remove the sparkplug.
  5. Dismantle the motor head.
  6. Look for scrapes, dents, or blasts around the gasket head.
  7. Skim for spigots and engine pistons' carbon residues.
  8. If you've proven that your lawnmower has a blown head gasket, you must replace it. If it's a false alarm, reconstruct all the parts.
  9. Turn on your lawnmower and inspect if an issue continues.

How To Fix A Lawn Mower Head Gasket?

There are several ways to repair a blown head gasket. But it depends on the severity of the damage. You can fix minor damages yourself by:

  • Cleaning the head gasket and other parts with the help of old gas and a paintbrush.
  • Using a head gasket sealant to block oil leaks.

Click here to see this product on Amazon.

A professional can fix it if the damage is severe. The cost will depend on the degree of the damage.

How To Replace A Lawn Mower Head Gasket

Sealing gasket in hand. The mechanic disassemble block engine vehicle. Engine on a repair stand with piston and connecting rod of automotive technology. Interior of a car repair shop.

If you decide to replace your lawnmower head gasket, here are the tools and steps.

Tools Needed

Here are the essential tools you need to replace the head gasket.

Wrench Set

You'll need a wrench set to grip, loosen, and tighten nuts and bolts.

Click here to see this wrench set on Amazon.

Key Features:
  • Easy to access and organize
  • Have stronger grip
  • Made of heat-treated chromium-vanadium steel

Ratchet & Socket Set

These tools are essential in removing lawnmower head bolts and such.

Click here to see this socket set on Amazon.

Key Features:
  • Polished and chrome-plated finish 
  • Large and easy-to-read markings
  • Perfect fit for double hex fasteners

Screwdriver Set

The screwdrivers are essential in removing various screws from your lawnmower.

Click here to see this screwdriver set on Amazon.

Key Features:
  • Durable
  • High-performance
  • Easy to store

Long Nose Pliers

You'll need various pliers, especially long-nose pliers, to remove things like the fasteners from the valve cover.

Click here to see these pliers on Amazon.

Key Features:
  • Has maximum gripping strength
  • Made from durable nickel chromium steel
  • Anti-pinch, non-slip ProTouch Grips

Torque Wrench

The torque wrench is used to tighten the cylinder head.

Click here to see this wrench on Amazon.

Key Features:
  • Accurate and precise
  • Durable and long-lasting
  • Easy to use

Feeler Gauge

The feeler gauge is used to set the valve lash.

Click here to see this gauge on Amazon.

Key Features:
  • Easy to use
  • Convenient
  • Dually marked for easy identification

Plastic Scraper

The plastic scraper tool is vital for cleaning and avoiding damage to the cylinder head, mower head, and block. 

Click here to see this scaper on Amazon.

Key Features:
  • Multi-functional
  • Compact
  • Safe to use


Below are the simple steps for changing your lawnmower's head gasket.

  1. Extract the pull assembly and blower.
  2. Take out the carburetor.
  3. Withdraw the muffler.
  4. Open the valve cover.
  5. Extract the pushrods.
  6. Unbolt the head bolts.
  7. Clean the head and block.
  8. Fit the replacement lawnmower head gasket.
  9. A torque wrench to tighten the head fit push rods would be best.
  10. Put back all the parts in the opposite order.
  11. Oh, and don't forget to change the valve cover gasket and check if you have enough fuel.

How Much Does It Cost To Fix A Blown Head Gasket On A Lawn Mower?

If you choose to have your lawnmower fixed by an expert, you must prepare considerable money. A head gasket repair costs $1200 to $3000 and typically lasts up to 10 hours.

How Do You Maintain A Lawnmower?

You must practice these things if you want your lawnmower to reach its full potential and maximum lifespan.

  • Change the engine regularly to avoid having bad fuel.
  • Pour energy stabilizer into the power system to keep the fuel fresh. Or empty all petroleum if you won't use your lawnmower for more than a month.
  • Change the spark plug with a brand-new one.
  • Clean and buy a new air filter.
  • Sharpen the blades after 20 to 25 hours of use.
  • Grind or hone into balance the blades. 
  • Maintain the cleanliness of your equipment.

5 Care And Maintenance Tools For Lawnmowers

To avoid mishaps with your lawnmower, you must take good care of it and its parts. Here are essential tools for maintaining and fixing your machine.

Lawnmower Maintenance Kit

The lawnmower maintenance kit contains the necessary tools to tune up and fix your lawnmower.

Click here to see this product on Amazon.

Key Features:

  • Easy to install
  • High-quality steel
  • Durable, sturdy, and waterproof

Wire brush

Wire brushes are perfect for the removal and cleaning of rust and oxidations, and other harmful exterior impurities.

Click here to see this product on Amazon.

Key Features:

  • Various sizes
  • Steel and brass
  • Long-lasting

Engine cleaner

 An engine cleaner is essential in cleaning and removing oil and filth from your lawnmower's engine. 

Click here to see this product on Amazon.

Key Features:

  • Removes grease, dirt, and grime
  • Rinses clean with water
  • No scrubbing

Blade Grinder And Sharpener

Your lawnmower's blade needs to be sharpened and balanced for effective use.

Click here to see this product on Amazon.

Key Features:

  • Easy height adjustment
  • Enhanced safety features
  • Portable


WD40 on your lawnmower's blades can keep the grass from clinging to the edges. It also helps keep the blades clean, sharp, and corrosion-resistant.

Click here to see this product on Amazon.

Key Features:

  • Low-odor formula
  • Safe on metal, plastic, and rubber
  • Fast-acting formula

How Long Can Lawnmowers Last?

Lawn mover on green grass in modern garden. Machine for cutting lawns.

Most lawnmowers survive for more than ten years with proper care, attention, and maintenance. Otherwise, you can foresee your lawnmower lasting 4-5 years. And if you use and abuse your lawnmower, expect it to last for only two years or maybe even less.

Final Thoughts

When mowing your lawn, a blown head gasket is the last thing you need. Overheating, terrible fuel, wrong or advanced ignition timing, and engine knock are the main reasons for this phenomenon. Keep them in mind and avoid them at all costs. 

If you need more information about lawnmowers, you can check these awesome posts:

Gas Coming Out Of My Lawnmower Exhause - What's Wong?

Oil In Lawn Mower Carburetor – What To Do?

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