Head Gasket Leaks: Causes, Symptoms, and Fixes

Cylinder head gasket leaks are not too common, but it’s an engine problem most car owners give much concern.

The Head gasket plays an essential role in ensuring there’s no leak within the combustion chamber. It acts as a sealing agent in the engine and protects the cylinder from engine oil and coolant mixing to ensure an optimal combustion cycle.

A leaking head gasket can be crippling. You can fix a cylinder head gasket leak with a few bucks using sealer products before it turns to an expensive engine repair.

In this article, we’ll discuss at length the causes of head cylinder gasket leak, symptoms, how safe it is to drive with it, and how to fix it.

Wait! Scratch that. Let’s get high.

Is It Safe To Drive With A Leaking Head Gasket?

head gasket leak repair cost

A small leak on a cylinder head Baker can turn into a significant leak in no time. So, pay explicit attention and fix the leak before it turns into an expensive repair job. While it may be safe to run with a head gasket leak for a short period, you don’t know what may happen along the way.

The leak may become obvious and expel much coolant on the ground or into the combustion chambers. Hence, it is advisable to fix the leak in the initial stage. The more you drive with that tiny leak, the more you expose your engine to a severe gasket leak.

The moment you have a severe leak, you face an expensive and (maybe a complicated) fix that may cause catastrophic engine damages if the mechanic cannot time the engine to appropriate sync.

If you have converted your vehicle to a road beast, when the gasket blows, it can lead to engine overheating or complete engine seizure. Therefore, you need to watch out for head gasket leak symptoms and resolve them at an early stage.

Head Gasket Leak Symptoms

It is essential to know the signs of a leaking and a blown head gasket to fix it and avert significant damage to the engine components.

External coolant leak: One of the notable symptoms of a leaking head gasket is a coolant leak between the engine head and the engine block. This happens when the engine is running at an average operating temperature.

It will be easier to identify if there are no coolant passages around this area. But if there is any coolant passage nearby, you need to determine where the coolant is leaking from before drawing a conclusion.

White smoke from exhaust tailpipe: As an external leak can occur, the leak can enter inside the engine compartment as well. Internal gasket leaks will allow coolant to creep into the combustion chamber. If this happens, the coolant will evaporate/burn during the combustion cycle and escape from the exhaust tailpipe as white smoke.

Remember, moisture can come out from the tailpipe as white smoke, and it’s normal. So, how do you differentiate these two? During a cold starting in the morning, a pleasant smell will accompany the white smoke resulting from an internal coolant leak. The smell may continue even when the engine is running hot. A billowed white smoke shows a severe internal coolant leak.

Milky or whitish Oil: one question I get in our garage from customers is, “what does a head gasket leak look like.” When an internal gasket leak occurs, and the antifreeze goes into the combustion chamber, it will creep from the piston rings into the crankcase and change the oil to a milky color.

You can see the milky substance on the engine cap or dipstick. The presence of coolant in the engine oil will cause it to lose its viscosity and cannot adequately lubricate internal engine components. It’ll allow sped-up wear in the inner engine parts like cam and crankshaft bearings on the cylinder walls.

Even if you park the vehicle in a garage without using it, the coolant in the oil will cause rust on machined surfaces, which can prompt the necessity for an engine rebuild.

Bubbles in the radiator: Aside from coolant creeping into the combustion chamber, internal gasket leaks allow exhaust gases to enter the coolant.

This will cause bubbles in the coolant reservoir or radiator, making the antifreeze look like it’s boiling even when the engine is below average operating temperature. The bubbles are a replica of the exhaust gases that passed into the coolant.

Overheating: The most common sign and cause of head gasket leak is engine overheating. Driving with a head gasket leak (no matter how small) will cause the engine to overheat if not rectified on time. While severe leaks cause the engine to run hot within some minutes, small leaks will keep the engine running as it should until the coolant goes below the specified level.

A severe overheat can cause internal engine parts to expand more than the designated size, causing component warps or cracks. It can also lead to a total engine breakdown, which will require a complete overhaul.

Dirty spark plugs: As coolant creeps into the combustion chamber and burns during the combustion cycle, it’ll leave whitish residues on the spark plug electrode. Other system problems can also cause these white residues. Hence, please don’t jump to a conclusion when you notice it.

head gasket replacement

What Causes Head Gasket Leaks?

If you have experienced a blown or head gasket leak, you may ask, “what causes a blown head gasket?” Several factors can be the culprits. Let’s explore them.

Mechanical force: The detonation in every engine outburst pressure or energy on each combustion cycle. It will continue as long as the engine keeps running, and over time, it’ll stress out the cylinder gasket, causing it to leak or even crack.

Heat: Internal combustion engines are known for generating excess heat during operation. That’s why there is a coolant to keep it under average operating temp. Even with the presence of the coolant in the engine water passages, the engine gets stressed out sometimes.

And because of the stress and thermal expansion rate between the engine block and the head cylinder gasket, the gasket will wear out and leak.

Vibrations: Let’s be clear; this happens on rare occasions. Regular vibration in vehicles as drivers commute to their daily activities stresses the head gasket.

You may wonder, where is the head gasket located? It is between the cylinder head and the engine block. Vibrations can slacken head cylinder bolts, stretch, weaken, and even warp in the long run.

These allow accelerated vibration and friction wear. Poor engine design can also cause vibrations after covering high mileage and lead to failure.

Overheating: Several issues like a bad radiator hose, a defective thermostat, a faulty cooling fan, and a lousy radiator, can cause engine overheating.

Another common cause is low coolant level. When coolant is inadequate and unable to pull out the heat produced during engine operation, the extra heat will expand the head gasket and cause leaks.

How To Fix Head Gasket Leaks

Head gasket leak repair is a complex job and requires tons of technical experience. Because of the job’s complexity, we cannot explain the step-by-step instructions needed for a complete fix in this piece. However, here are a few options for handling a leaking head gasket.

Using Gasket Leak Products

While repairing gasket leaks is pretty expensive. In some cases, it requires a few bucks to fix it and start exploring a seamless driving experience. If the engine can run for 15-20 minutes without overheating, there’s a chemical to stop the gasket leak without taking off the cylinder head.

Using head gasket leak sealers does not require any technical knowledge. In fact, it’s as simple as pouring coolant into a radiator or coolant reservoir.

There are tons of head gasket sealer products out there that promise to do a complete sealing to the cylinder head. Some of these promises are mere marketing tactics. However, there are some gasket sealers on some auto store shelves with a solid gold reputation to protect. Here’s a list of the pros and cons of using gasket sealants.

Every car engine is different, and you need to follow instructions on how to use the products. These products are not an eventual stop to gasket leak issues, but they can keep running with confidence on the wheel for a few thousand miles.

Pay For A Repair

The cost of fixing a leaking head gasket can be pretty expensive. It is like giving a blank cheque to the technician. First, it required the mechanic to perform a test to confirm the gasket is leaking. After confirming the leak, labor is necessary to drop the head cylinder.

Once the head cylinder is separated, several potential issues may be seen, which will require extra labor, extra hours, and extra money. There’s a possibility that the machine will charge you to dismantle the head cylinder, only to discover a crack on the engine block that will require replacing the whole engine.

Pay For A New Engine

If the head gasket leak has severe damage, a total engine replacement is a good option. It’s possible to get a sound-used engine for a lesser or equal amount of head gasket leak repair cost. Here, you will need to install the engine yourself or pay a certified mechanic to do it.

Replace It Yourself

Whether you are a gearhead or an entry-level mechanic, there are some parts of the job that require professional services, such as resurfacing and grinding the cylinder head. So, do not do this yourself unless you have a wealth of experience and all the tools required for the job.

If you choose to carry out all the repair jobs yourself, get a service manual for the car for detailed instructions to guide you to remove the head gasket. Before reinstalling a new head gasket, clean the machined surfaces and ensure it is clean and even.

Don’t forget to inspect other related components. When replacing a head gasket, check and replace anything that could cause the leak, including cylinder walls, coolant system components, and several other parts. It’s much easier to inspect, test, and replace old parts when the engine is dismantled.

Buy A New Car

If you own an old ride that has covered over 100,000 miles that holds little value over repair cost, it may be a good time to dump it on a scrapyard. I know it’s hard to let go, but it may be a better option.

Related FAQs

Can you drive with a leaking head gasket?

You can drive with a leaking head gasket, but I doubt you won’t want to do that because even a slight head gasket leak can turn into a major one. You may not know when all the coolant will dump on the ground or inside the combustion chamber.

The longer you drive with (even a tiny) gasket leak, the more you are exposed to severe engine damage.

How much does it cost to repair a leaking head gasket?

The cost of replacing a leaking head gasket can be pretty expensive, meaning scrapping your vehicle may be a viable option if you have high mileage on your ride. The average cost of fixing a leaking head gasket is between $ 1,000 and $ 3,000, but it doesn’t mean the replacement parts are expensive.

The high cost of repairing a head gasket leak stems from the job’s complexity and extra hours involved. The fixing requires removing the cylinder head before replacing the faulty gasket.

If you identify the leak at the initial stage, you can fix it with a few bucks by using a head gasket sealer.

Is it worth fixing a head gasket leak?

When asking if it is worth fixing the head gasket leak or not, consider the value of your car. If your baby ride is worth several thousand dollars or thrice the repair cost, it’s still okay to fix it. However, if you have an old vehicle, repairing the gasket leak is a waste of money.

Can I replace a head gasket myself?

It is pretty easy to seal a head gasket leak with a gasket sealer. These chemical products can work well at the initial stage of the leak. If you allow the leak to expand, it will require replacing the head gasket with a new one.

Replacing a head gasket is a complex and time-consuming task that requires technical knowledge. That said, unless you are a mechanic, you won’t be able to replace it. Taking off the cylinder head requires disconnecting the crankshaft from the camshaft. Can you set the engine timing incorrectly?

Will a check engine light come on for a blown head gasket?

One of the terrifying causes of a check engine light is a blown head gasket. The purpose of the engine oil is to reciprocate the internal engine parts – if coolant mixes with the oil, it will cause it to lose its viscosity.

Once the oil cannot lubricate internal engine components correctly, it will trigger the engine warning light to notify the driver of an imminent issue.

How many labor hours does it take to replace a head gasket?

The exact hours and cost required to replace a head gasket depend on the severity of the leak, and if the head cylinder and engine block are serviceable.

If the overheating that blew the head gasket was severe, the head cylinder and the engine block would need to be resurfaced or replaced because these parts may warp. In a nutshell, the total hours for replacing a head gasket is between 3 to 10 hours. The hours include the grinding or resurfacing hours.

Final Word

You have seen the causes, symptoms, and various options for fixing a head gasket leak. It is better to seal the leak earlier before the problem escalates to a bigger one.

Don’t risk getting stranded in the middle of nowhere or causing catastrophic damage to your vehicle’s engine. Choose the best suitable option and fix the leak.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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