What Are Head Gasket Sealants?

Positioned between the engine block and the cylinder head, the head gasket seals the cylinders, creates optimal compression, and avoids coolant and oil leaks. Your vehicle can't run without an effective head gasket, so you'll want to address a blown gasket quickly. Find out what head gasket sealants can do, and how to use the right one for your vehicle.

Suggested AutoZone Products

What Head Gasket Sealants Do

These sealants are designed to fix head gasket failures, but using a sealant isn’t the only way to address a failure. You can use a torque wrench to tighten the cylinder head bolts or change the head gasket altogether. Because the the head gasket is between the cylinder head and the engine block, replacing it can be complicated and require disassembling major engine components. Using a head gasket sealant is the easiest fix. This liquid stop leak is made to track down the source of a leak and fix it quickly so you can get back behind the wheel in less than an hour.

Signs of a Blown Head Gasket

  • A mayonnaise- or milk-like mixture in the oil: An off-white creamy appearance on the dipstick signals that the coolant has probably mixed with the oil. This can also be caused by a leaking intake manifold gasket. If the intake gasket is OK, consider changing the oil and replacing the head gasket(s) altogether
  • Unresponsive engine: One of the most common signs of a head gasket approaching failure is a slow or unresponsive engine
  • White smoke coming from the exhaust pipe: White smoke can show water from the coolant is leaking into the combustion chamber
  • Blue smoke coming from the exhaust pipe: Blue smoke often signals oil is leaking into the combustion chamber

Using head gasket sealant is relatively easy. Always read the instructions on the bottle. You may see some variety, but most sealants follow similar steps.

How To Use Head Gasket Sealant

1. Mix the product

Shake the bottle to mix the sealant.

2. Flush the radiator

Use distilled water or a flushing agent until the draining fluid appears clear. This is especially important if the system is dirty, such as if coolant and oil have mixed.

3. Determine how much sealant you need

It will vary depending on the number of cylinders.

4. Prepare the radiator

Fill the radiator with water, but leave an appropriate amount of room for sealant.

5. Warm up the vehicle

Let the vehicle idle a few minutes and turn the heater on high to get the engine nice and warm.

6. Pour in the head gasket sealant

Add the sealant slowly and replace the radiator cap. (Note: Some vehicles do not have radiator caps. The fluid and sealant are added through the radiator over flow reservoir.) Let the vehicle idle for about 45 minutes while monitoring the temperature gauge and ensuring that the temperature stays within the normal range.

Keeping your vehicle’s head gasket intact and working properly is critical. If you think you’ve got a leak, stock up on head gasket sealant at AutoZone.

Advice, how-to guides, and car care information featured on and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

FREE Loan-A-Tool® program requires returnable deposit. Please note that the tool that you receive after placing an online order may be in a used but operable condition due to the nature of the Loan-A-Tool® program.

Related Posts