A blown head gasket is always bad news to your engine. It needs immediate repair. If you don’t attend to it, chances are it will ruin your engine’s core. The key to surviving a blown head gasket is knowing the signs in advance.
When a head gasket goes bad, it leaves some openings between the head and the bottom cylinder block.
The most significant cause of a failed head gasket is when the head and the block expand and contract at different rates. This is common in engines with an aluminum head and an iron block.
Sometimes, the damage could be due to lower than required clamping force from the head bolts.
Signs that Your Head Gasket is Blown
Head gaskets seal a couple of things at a go. First, they prevent oil, coolant, and engine compression from escaping or getting into each other’s way. Unfortunately, this means when the gasket blows, very many things can go wrong. Here are the top things that will happen when you have a blown head gasket.
An Overheating Engine
Many things can cause an engine to overheat. The most common is a damaged cooling system. However, a blown head gasket can also mess up the engine’s cooling hence making it overheat.
Hot exhaust gases will leak into the cooling system overworking it. Alternatively, coolant could lead into the cylinders and burn up. This leaves your car with no cooling juice hence overheating it.
An overheating engine can warp cylinder heads, while the evaporating coolant could ruin your catalytic converter.
Contaminated Oil
Another sign that you have a blown gasket is a milky sludge in your oil system. The milky deposit could be on the underside of the oil filler cap or visible in the oil filter.
If the damage is too much, you could see some of the milky patterns on the dipstick every time you pull it up to inspect oil levels.
Coolant infiltrating the oil system won’t be long before your oil loses its lubricating abilities.
This leaves your engine bearings and other moving parts of your engine exposed to frictional damage. Don’t keep driving when you notice this. Instead, have the head gasket replaced and the entire oil system flushed.
Contaminated Coolant
If there is a leak between the oil and the coolant systems, chances are there will also be oil residue in your coolant. Your coolant will no longer be the new color it was when you bought it.
You will see traces of oil floating in it when you open the coolant reservoir bottle. Sometimes, if more oil is leaking into the coolant than coolant is leaking into the oil reservoir, the coolant levels might seem to go up a bit.
Loss of Power
If the failure allows compressed air and fuel to leak out before the ignition cycle, the cylinders no longer attain the compression levels they need for optimal performance.
The engine will run rough. In addition to this, you will have reduced engine power, and your car will either stall when starting or accelerate sluggishly even with the pedal to the metal.
White Smoke from the Exhaust
When coolant leaks into the cylinders and burns up, it produces white smoke. The white smoke also has a sweet smell.
The sweet smell is from the additives in the coolant, while the white smoke is mostly steam from the water in the coolant.
An oil leak into the cylinders, on the other hand, will produce a cloud of blue smoke. However, this is often less noticeable. You have to be very keen to see it.
Visible External Leaks
If the head gasket is open to the outside of the engine, you could have visible oil and coolant leaks around the point where the head gasket seats.
This is easier to notice on a clean engine. First, inspect the engine all around for any residue that shouldn’t be there. If it is already dirty, you could have it cleaned or add some oil leak additives to your oil and run the engine to see if new leaks add to the existing gunk.
Drops in Coolant or Oil Levels With No Visible Leak
Another easy to identify sign that you could have a damaged head gasket is dropping coolant or oil levels without a visible leak.
If the levels are dropping and you can’t see any of these fluids under the car or on the engine block like in the case of a valve gasket leak, chances are they are leaking into the engine and burning up with fuel.
Check your exhaust too. You might find the white or blue smoke to reinforce this deduction.
How Does a Head Gasket Fail?
Since the head gasket handles so much, it could fail in a couple of ways. Here are the top things that happen when a head gasket fails and how each failure reflects itself.
Compression Leaks Into Your Oil Chambers
If the head gasket fails between a cylinder and the oil gallery, compression will leak out of the cylinders and into the crankcase. In addition, the gases make it harder for the oil to lubricate crucial parts like your crankshaft’s main bearings.
This failure could also suck oil out of the galleries and into the cylinder. The oil will burn during the combustion stroke. The result will be some blue smoke whose intensity varies depending on the extent of the leak.
You will eventually notice considerable drops in oil levels. You will also hear noises if the lubricant loss within the engine is severe as vital moving components run dry and fail shortly after.
Coolant Leaks into the Oil
If the gasket leaks at the point where it separates your oil from the coolant, you could have some coolant in your oil.
The result is that milky residue in your oil shows in the dipstick or on the oil filler cap.
You could also see oily residues in your coolant if the same compromise lets oil leak into your coolant.
Coolant Leaks to the Outside
The casket can also fail at the point where the coolant runs next to the outside of the engine.
In this case, the coolant won’t mix with anything, but it will just leak out. As a result, you will see your coolant levels drop.
Additionally, you can identify tell-tale coolant leaks like:
Coolant on the engine block
The color of your coolant staining the engine block as it burns up
A sweet smell from under the hood as the hot engine block burns up the exposed coolant from the leak
Compression Leak to the Outside
Some engines are designed such that the head gasket seals the blocks at a point where one or more cylinders are exposed to the outside.
Damage at this point will let coolant leak to the outside. An excellent way to identify such a leak is by listening to a ticking sound when your engine is idle.
You will also experience an engine that runs rough and isn’t as powerful as it should be.
Compression Leak Between Cylinders
All the cylinders in your engine are designed to operate independently. However, some engines could compromise this setup if they are prone to inter-cylinder gasket damage.
The result could be lost compression or exhaust gases flowing back into the intake stroke. It all depends on the timing of the adjacent cylinders.
Either way, your engine will lose power and run rough.
Oil Leaking to the Outside
Just like coolant could leak to the outside, a faulty head gasket could leak oil to the outside of the engine.
Look for wet oil streaks at the point your head meets the engine block. Oil leaks are easier to identify in clean engines, though. This is one reason why I like detailing my engine bay.
You can also use an additive that makes oil glow under a special light to pinpoint engine oil leaks.
Don’t hesitate to troubleshoot for an oil leak if you notice that your engine consumes oil faster than usual.
Compression Leaking into the Coolant
The last head gasket failure to expect is the one that leaks compression into your car’s cooling system.
If this happens, the gases will pressurize the cooling system and overheat it. When it is mild, you will see bubbles (boiling) coolant in return and even intake hose connections at the coolant reservoir.
When the compression leak and overheating are severe, the extra pressure could exceed the cooling system’s rating leading to blown hoses. The hoses are violently blown off a weak joint or pressure hisses forcefully through a weakened point in the cooling system.
How to Fix a Head Gasket Leak
Fixing a head gasket leak is expensive and complicated. Even though the head gasket itself is cheap, it takes a lot of work to disassemble the engine and get to where it’s located.
As such, the cost will vary depending on how much your mechanic charges per hour.
Nonetheless, there is no localized fix to the problem. Any leak, no matter how small, translates to a blown head gasket. You have to replace the entire thing.
Can I Drive With a Blown Head Gasket?
While your engine will still run with a failed head gasket, you are putting too much strain on its internals if you keep running it. Chances are it will ultimately fail on your when you least expect it.
Failure to fix it will lead to frequent overheating, damaged bearing, fouled lifters, and even warped cylinders.
Since it might take time to notice a blown head gasket, taking your car in for repairs ASAP is good for its longevity. Of course, you could try sealing additives, but they are temporary fixes.
The right solution is to have the gasket replaced.
What Does a Blown Head Gasket Sound Like?
A blown head gasket doesn’t necessarily lead to an audible sound. Since there are over seven ways the gasket can fail, looking for a sound could be misleading if the gasket fails differently.
You will only hear a sound if the leak compromises lubrication, making internal engine parts rattle more. You will also hear a ticking noise if the leak lets compression leak to the outside.
Does a Blown Head Gasket Make a Knocking Noise?
Yes. You could hear a rapid knocking sound if the failed gasket lets compression leak to the outside.
Not that the knocking sound should change pitch with engine RPM. Use this sound in conjunction with other signs to diagnose a failed head gasket.
Is it Worth Fixing a Blown Head Gasket?
Even though fixing a blown head gasket could cost in the thousands depending on how much your mechanic charges for labor, it’s still a worthy repair.
However, at times, you could opt to skip fixing the damage if the car is very old and you don’t attach any sedimental value to it.
Head gaskets take long – unless you misuse a car. But then, by the time it blows, other parts of your vehicle could also be failing.
If you are on a budget, you could always compare how much it costs to replace the gasket compared to get another used car.
It’s not unheard of to get a great used car without spending more than $5000. But, of course, it depends on what car you are going for.
My Point: Let someone else fix it if you can get a similar car or something better by adding around $500 to $1000 on the price the repair shop asks for to do the job.
How to Prevent Head Gasket Failure
Most head gaskets fail when you operated your car’s engine beyond its specified temperature limits. Repeated overheating will warm the joints between the two engine parts hence forcing the gasket to fail.
An excellent way to avoid this is by closely monitoring your cooling system and car’s temperature gauge. Never let an overheating engine go unattended to. Please find out the cause of the overheating and fix it as soon as possible.
Bottom Line
I failed head gasket spells nightmare. However, you shouldn’t be afraid to have it fixed, especially if you surmise that your car costs way more than the money you’ll spend fixing it.
Also, it would be best first to explore other possible causes of the problem you are facing before concluding that the head gasket is the problem. For example, a misdiagnosis can happen if you have tunnel vision and zero down on the gasket without exploring other causes for that coolant leak or oil leak.