Exmark Kohler Engine Oil Leaking Blown Head Gasket: Diagnosis and Fixes

A blown head gasket in your Exmark lawnmower’s Kohler engine can cause oil to leak. Before you consider the best possible fixes, it’s necessary to confirm that the head gasket is the culprit. Symptoms of a blown head gasket can resemble those of other Exmark mower issues. So how do you know that the head gasket is the origin of the oil leak?

Herein, I detail how to diagnose and fix an Exmark Kohler engine oil leaking blown head gasket. You’ll also learn the common causes and symptoms of a blown head gasket in Exmark mowers with Kohler engines.

Causes of a Blown Head Gasket

The head gasket prevents oil from leaking and ensures pressure does not leave the engine compartments. If it’s blown, oil tends to leak and might enter the combustion chamber, causing significant damage to the engine.

If your mower has a blown head gasket, the possible causes could be bad fuel, faulty combustion timing, and engine knocking while running. These problems increase pressure in the cylinders and damage the head gasket.

Once the head gasket is blown, your mower might have issues such as oil seeping into the combustion and pressure leakage.

A blown head gasket should be fixed on time to avoid costly repairs or replacements. If not fixed timely, it might cause the following;

  • Damage to the spark plug
  • Damage to the piston head
  • Ruin the cylinders
  • Ruin the engine and make it permanently unusable

To avoid such issues, check if a blown head gasket in your Exmark mower causes oil to leak and fix it.

Diagnosing a Blown Head Gasket

Here are the things to check when diagnosing a blown head gasket.

Check for the Common Symptoms

Run the engine and observe the color of smoke coming from the exhaust. White smoke can be an indication that you have a blown head gasket. You may also notice that the engine behaves erratically when in operation.

You can also check the oil level to see if you suspect an oil leakage in the engine. If the oil level is low, add new oil and recheck the level after a while. An internal leak will cause the oil level to drop. In this case, you can check the head gasket to see if it’s blown.

Next, inspect the condition of the spark plug. Your mower might have a blown head gasket if it’s covered with oil.

Check for Loose Cylinder Head Bolts

Before inspecting the head gasket, check the cylinder head bolts to see if they’re loose. If you find them loose, there’s a good chance that they’re the cause of a leaking head gasket. Thankfully, you can fix this by tightening the bolts.

Inspect the Head Gasket

Locate the head gasket between the cylinder head and the cylinder block. You can unscrew the cylinder head bolts to access the head gasket.

Do this carefully to avoid damaging the gasket. Check the head gasket for signs of wear or damage. If you find cracks, discoloration, or metal build-up, your head gasket might be blown.

Disconnect and Reconnect the Spark Plug Lead

The aim is to see if pressure is escaping around the cylinder head and cylinder block joint. Start by cranking the engine and disconnecting the spark plug lead. Reconnect the spark plug lead and inspect if there’s steam trying to escape around the joint.

If you hear the sound of escaping air or notice high-pressure steam escaping, there might be a leakage in the head gasket.

Conduct a Compression Test

A compression test can effectively diagnose an Exmark Kohler engine oil leaking blown head gasket. Start by disconnecting the spark plugs.

Thread the compression and crank the engine. Then check the compression tester readings of each cylinder. If the test shows 0 psi on both cylinders, the head gasket might be blown.

How To Fix a Blown Head Gasket

After confirming that the head gasket in your Exmark lawn mower is blown, look for the best ways to fix it. Unfortunately, you can only replace your mower’s blown head gasket. The replacement process is complex and time-consuming.

If you don’t have the technical skills and necessary tools, take your mower to a professional mechanic to replace the blown head gasket. Alternatively, you can replace the head gasket yourself by following this step-by-step approach:

  • Drain the oil: Start by removing the oil fill cap. Then, locate the oil drain plug and remove it to allow oil to flow into the drain pan.
  • Remove the spark plug: Start by disconnecting the spark plug wire. Then unscrew the spark plug using a spark plug wrench.
  • Remove the cylinder head: Unscrew the cylinder head bolts using a socket wrench. Once the bolts are out, remove the cylinder head slowly to avoid causing damage.
  • Inspect the cylinder head: Replace the cylinder head if it is damaged or has cracks.
  • Remove the blown head gasket: The old head gasket is attached to the head cylinder. Unscrew the bolts to remove the head gasket.
  • Clean the cylinder head: If the cylinder head is in good condition, submerge it in soapy water, then use a soft brush to clean all the dirt, oil, and rust. Ensure there’s no debris left on the cylinder head surfaces.
  • Install the new head gasket: Apply sealant on the new head gasket before installing it. Then, install it on the cylinder head by tightening the bolts using a socket wrench. Ensure to use the correct torque specification when tightening the bolts.
  • Reinstall the cylinder head: Use the cylinder head bolts to reinstall the cylinder head to its rightful position.
  • Reinstall the spark plug: Reconnect the spark plug wire and reinstall the spark plug.
  • Add fresh engine oil: Before filling the engine with fresh oil, seal the drain opening with a new oil drain plug. Use high-quality oil according to the manufacturer’s specifications.
  • Test: After ensuring everything is installed correctly, run the engine for a few minutes. Then, inspect if there’s any sign of oil leakage. If no oil leaks from your Kohler engine, you have successfully fixed the problem.

Final Thoughts

An Exmark Kohler engine oil leaking blown head gasket can be a troublesome issue. If allowed to remain in the mower, a blown head gasket can damage your Kohler engine. You don’t want the leaking oil to enter the combustion chamber and wreck your engine.

If you suspect the head gasket is blown, diagnose and replace it if necessary. You can use the above diagnosis tips and replacement steps to fix a blown head gasket. If you don’t have the skill or necessary tools, take your mower to a repair shop for diagnosis and fixing.