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What Causes a Blown Head Gasket?

What Causes a Blown Head Gasket?

A head gasket is one of the most important yet underrated parts of any car's engine. The average driver likely has no idea what a head gasket is or where to find it because the nuts and bolts of how a car works aren't really known to most people, so to speak. However, it's good to know not only where your head gasket is but what it does and why it can fail on you. When you have a blown head gasket it can cause some serious headaches in terms of damage to your vehicle as well as potential repair bills. But the first thing you need to understand is what causes a blown head gasket to begin with.

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 Let's take a look at what your head gasket does, where it is located in your vehicle, what can make it go bad and how you can go about fixing the situation.

 What is a Head Gasket?

Like any gasket, a head gasket is meant to seal part of your engine. In this case the gasket seals the space between the cylinder head and the engine block. From the outside of your engine, you won't really see the head gasket at all. It's a very thin piece of material that is held snugly between these two parts of your engine. It's also full of holes that fit around the cylinder openings so there's not actually a lot of material involved in the construction of a head gasket either. That doesn't make it unimportant, however.

 Made from an elastomer material and thin sheets of steel, the head gasket maintains the pressure in the combustion chamber of your engine. Without the head gasket in place, you would lose pressure in the combustion chamber which would throw off the timing of the combustion reaction. Your pistons would potentially be rising and falling at the wrong time, you might have the fuel and air mixture injected at the wrong time and the spark happening at the wrong time as it relates to actually having combustion occur.

 In addition to maintaining pressure in your engine, the head gasket also has an important job in keeping the combustion chamber free from contamination. If you blow your head gasket and develop breaks and cracks in the material, then coolant and oil can both leak into your engine. This can cause a number of problems that can be time-consuming and expensive to fix.

 What Causes a Blown Head Gasket? 

Given where a head gasket is located and what it's made of, there aren't a lot of ways that it can be damaged. However, there are a few common causes for blown head gaskets that you'll need to be on the lookout for.

Overheating: This is arguably the main cause of any problem's drivers have with head gaskets. Your engine is designed to work at a certain temperature. Within a range of temperatures everything will be fine. However, if you forget to change your coolant or you run low on motor oil, and even if you are running your engine and extreme weather conditions, your engine can start running hot. If you allow the engine to stay too hot for too long aside from a number of other potential problems that you can cause, you'll also be causing extensive wear to your head gasket as a result.

Because your head gasket has metal inside of it, it is susceptible to extreme temperature changes. Metal expands in heat and contracts when it gets cooler. So, if your engine is continually getting very hot, hotter than it's supposed to, and then cooling down again it's going to cause your head gasket to break down eventually.

Contamination: As we said, part of your head gasket's job is keeping fluids like coolant and engine oil out of your combustion chamber. But the head gasket will still be exposed to coolant and this could potentially wear it down if your coolant is badly contaminated. If you haven't changed it in a while the chemical composition could be corrosive enough to start wearing away at the elastomer substance that makes up your head gasket. In time, it will eat away at the material and cause cracks and breaks.

Defect:  Although rare it's not impossible that the head gasket installed in your vehicle will have suffered a manufacturing or installation defect of some kind. If it was installed slightly incorrectly or something compromised it during the manufacturing process it could be weakened from the very beginning and just normal use of your vehicle will cause it to crack and break. It's always good to monitor any technical service bulletins that have been issued by the manufacturer for your particular make and model of vehicle, as well as recalls in case they cover this kind of problem.

Signs and Symptoms of a Blown Head Gasket

When your head gasket does go bad there are a few signs that you're going to be able to look for to let you know you have a problem.

Overheating:  Even though overheating is actually one of the causes of a blown head gasket it's also one of the symptoms. Because the cracks in your head gasket are going to allow coolant to escape, that means the coolant won't be able to do its job in maintaining the temperature in your engine.  If you noticed that your engine temperature gauge on the dashboard is routinely running into the red, it's very possible that you're suffering some kind of a coolant leak which could be contributing to a blown head gasket. Since it's both the cause and symptom, the longer this is allowed to continue the worse it's going to make the situation.

Poor Engine Performance: Because your head gasket is no longer maintaining the pressure in your engine, you're going to notice some serious performance issues as well. This could include engine stalls or stuttering, even misfires. This is all the result of the combustion reaction not occurring the way it should any longer because the lack of pressure has thrown off the timing. 

Bad Coolant: You can potentially have two issues with your coolant to let you know there's a problem with your blown head gasket. First would be low coolant levels because the coolant is leaking out from the cracks in your head gasket. The second problem would be contaminated coolant. Because oil and coolant can now mix together through the gaps and breaks in the head gasket, you may notice oil has contaminated the coolant reservoir. It will float to the top of the coolant and thicken there, looking like a layer of mayonnaise. You'll also likely have the same thick layer on your radiator cap when you take it off.

Bad Oil: When coolant gets into your oil reservoir, you're also going to notice a contamination issue. In this case your oil when you go to check it, instead of looking the way you're used to, will be frothy and something like a milkshake. You'll need to do a complete oil change in order to get it working again properly. 

 Does a Blown Head Gasket Ruin an Engine?

While a blown head gasket can cause serious problems for your vehicle, it doesn't necessarily mean that your engine is ruined by any means. With that said, you don't want to be driving around with a blown head gasket for too long because you definitely could end up ruining your engine if you don’t get it fixed in a timely manner. The kind of damage caused by a blown gasket will get worse over time if you don't fix it. Because you're going to be potentially leaking coolant and oil, your engine is going to start overheating. That can lead to serious damage down the road with warped cylinders, valves, and pistons. So theoretically a blown head gasket could ruin your engine, but you really have to let it go for quite a while without repairing it in order for that to happen.

Your best bet whenever you realize you have a blown head gasket is to get it repaired or replaced as soon as possible. This will save you a lot of time and frustration in the long run. Even though this is a potentially expensive fix depending on the nature of the damage, not getting it fixed will end up costing you much more down the road.

What Does it Cost to Fix a Blown Head Gasket?

When it comes to fixing a blown head gasket you have basically just two options available to you. If your head gasket is badly damaged enough then you're going to need to take it to a mechanic to get it replaced. While the head gasket itself may not be a very expensive item, you can buy them brand new from auto supply stores like AutoZone for anywhere between $20 and $50, that's just the parts fee. Unfortunately, in order to replace a head gasket a mechanic is going to need to essentially take your engine apart. This is a very labor-intensive job, typically well beyond the skill level of a home mechanic, and as such it can end up costing you between $1,000 and $2,000 to get done.

 Fortunately, there is also a second option that may work depending on the nature of the damage your head gasket has suffered. You may be able to repair the head gasket rather than replace it and doing so will save you quite a bit of time and money if it works.

You can buy products called head gasket leak sealers that may be able to fill in the cracks and holes in your head gasket without having to take your engine apart. You could find these products for sale at any auto supply store, even online on Amazon.com. It's a liquid substance sold in bottles that you pour into your car's radiator. Once the leak sealer is in your radiator it will filter through your car's coolant system. 

When the leak sealer reaches the cracks in your head gasket the chemical compound will fill in all of the holes and the heat of your engine will cause it to harden in place, sealing the gaps that have formed.

 Depending on how badly damaged your head gasket is, this could be a near permanent solution if you buy the right kind of leak sealer. Not every kind is meant for heavy duty repairs, some may only offer a stopgap solution of fixing your head gasket for a couple of months. Others boast that they will be able to repair your head gasket to an almost like-new condition.

You need to make sure that you buy the right kind of leak sealer for your vehicle. Obviously a V8 engine is going to be bigger than a 4-cylinder engine so you're going to need more leak sealer and potentially a different brand. You'll have to read the instructions very carefully to make sure you're using it right. Many drivers have discovered that if they don't follow the instructions exactly as listed, the product won't work at all and you will have wasted your time and money.

If you do follow the directions exactly and the damage to your head gasket is not so severe that it can't be repaired, then a head gasket leak sealer could potentially fix your problem and get you back to driving your car again with no troubles. Head gasket leak sealers only cost around $50 to $120 for a bottle depending on how much you need and what brand you choose.

Make sure you check out some online reviews to make sure the product is high quality and not something that's going to fail again within a month of use. Products like Steel Seal and Blue Devil have incredibly high praise from most users, so you should have no problem choosing one of those

The Bottom Line

Even though the head gasket seems small and insignificant, the damage it can cause to your engine if it goes bad can be extremely expensive and frustrating. Make sure you're changing your oil and your coolant according to your manufacturer specifications to keep your engine running smoothly, cleanly, and at the right temperature. All of this will help ensure that your head gasket stays in good condition for as long as possible.