A white, creamy buildup on the underside of the oil filler cap is sometimes referred to as “mayonnaise” and indicates a leaking head gasket. A lack of white build up does not necessarily mean the head gasket is not leaking.
As the leak in the head gasket grows, the exhaust will become whiter.
Light swirls in the oil are likely caused by coolant. If there is enough coolant to make out the color, coolant is usually green, orange or pink.
A misfire will often result in the check engine light coming on in your dashboard. A leaking head gasket is one of a number of issues that may cause the check engine light to come on.
If the error code indicates a misfire, it may be a result of a bad head gasket. Many auto parts stores will use their OBDII scanner to check your codes for free.
If your vehicle is overheating, immediately pull over and shut the engine off. Driving an overheating vehicle can cause significant internal damage to the engine and cylinder head.
Once the vehicle is jacked up, place jack stands beneath it to support the weight. If you are unsure of where to find the designated jack points for your vehicle, refer to the owner’s manual. Never work on a vehicle supported only by a jack.
Place the container beneath the radiator on the end with the petcock. Refer to your vehicle’s service manual to determine the coolant capacity you will need to keep in a container.
Be careful not to allow any of the coolant to leak from the container as it is bad for the environment. Opening the radiator cap will allow the system to drain quicker.
If the radiator cap appears to be severely worn or damaged, you should replace it by purchasing a new one at your local auto parts store. Check in the service manual for your vehicle if you are unable to locate the radiator cap.
Disconnect the line leading to the top of the thermostat. Check the service manual for your specific vehicle to help you find the thermostat if you are unsure.
Allow the vehicle to run for ten minutes or so. Keep an eye on the temperature gauge and turn the vehicle off immediately if it begins to overheat.
This is the same process you would use to drain and flush your coolant system. The water will flush out the coolant that was elsewhere in the coolant system the first time you drained it. Reconnect the thermostat during this step.
You can purchase pre-mixed coolant and water, or you may choose to mix it yourself. Add coolant through the radiator cap and give it a minute to drain into the system, then continue to add more until you reach the coolant capacity.
You can usually simply pour the sealer into the radiator cap along with the coolant and water.
Again, if the vehicle begins to overheat, stop the engine immediately. After fifteen to twenty minutes, stop the vehicle and allow it to sit for a few hours.
Keep an eye out for the symptoms of a leaking head gasket after using a head gasket sealer. Having the head gasket replaced is the only truly permanent solution to a leaking head gasket.
