Blown Head Gasket – Time to Scrap Your Car?

What is a head gasket? What does a head gasket do?

The head gasket prevents coolant and oil from mixing by sealing off the internal combustion process.

It’s situated between the cylinder head which is at the top of the engine and the block, which is the engine’s main structure.

Of all the gaskets in the engine, this one is under the most pressure since it needs to seal oil, coolant and compression from the cylinders at once.

The head gasket seals off the oil passages between the cylinder head and block, allowing oil to flow around the motor freely. Just as it does for waterways, it allows coolant to move where needed.

How could a head gasket become faulty?

It can be hard to spot problems with the head gasket since it’s mostly hidden in a functioning engine.

Overheating often leads to a puncture in your gasket or the dreaded blown head gasket.

But pre-ignition trouble could lead to fuel combusting at the wrong time, resulting in large pressures in the cylinder head and small holes deeper inside.

If it’s a faulty head gasket or one that isn’t installed correctly, it may end up blowing later. Head bolts need to be tightened just enough that they form a seal, but not so tightly that the gasket is crushed and unable to produce a seal.

Is it ok to drive with a blown head gasket?

Driving with a blown head gasket is possible, but not advisable. Once the seal is broken, pressure in the combustion chamber will be lost and power will be reduced.

If there is a coolant leak due to a blown head gasket, your engine is more prone to overheating. Continuing to do this will cause further breakage and damage to your engine.

When motor oil mixes with coolant it gets diluted, so it can’t lubricate as well, and this could result in irreparable damage.

5 Signs You Have a Blown Head Gasket (and How To Prevent It)

1) Overheating

A blown head gasket can be caused by an engine overheating multiple times (due to a clogged radiator, a coolant leak, and/or a defective fan), but an overheating engine that is typically not cared for often will be prone to a Head Gasket failure.

Driving the car while it is overheating can cause the cylinder head to warp and steam to damage the catalytic converter, resulting in expensive repairs.

2) Perhaps a Loss of power

If the head gasket fails in a way that allows compressed air and fuel to escape, then the compression of that particular cylinder will decrease. This lack of compression causes a bumpy running engine and a significant decrease in engine power. When this type of malfunction occurs, it usually produces a sound similar to an exhaust leak.

3) Your Oil may become contaminated

A classic indication of head gasket malfunction is the presence of a milky sludge on the underside of the oil filler cap or dipstick, lovingly referred to as a “milkshake”. Coolant spilling into the oil, and the other way around, is what causes this. This isn’t definitive evidence that your head gasket has failed, but it’s usually a good indication and is sure to mean you need to take apart the engine to figure out what’s causing the contamination.

Driving with oil contaminated by antifreeze will quickly damage the engine’s bearings. In order to repair an engine, it needs to be flushed with oil and a new filter is needed. Usually, the bottom end of the engine must be taken apart in order to verify that its bearings are not damaged and all contaminated oil is removed.

4) White Smoke

A head gasket issue usually causes a lot of white smoke with a sweet smell coming out of the exhaust. This occurs when antifreeze seeps past the gasket into the cylinders, where it transforms to steam during the combustion process. Although not as common, a leak from an oil passage to the cylinder could still cause blueish smoke.

If either of these gasket failure issues occur, combustion pressure can enter the cooling system or oil breather system. If you find that a radiator hose has come loose from its water outlet or the dipstick keeps slipping out, this might be why.

5) External leaks

If a head gasket has failed between the water or oil passage and outside of the engine, it can cause minor coolant or oil leaks. Although this is the least serious consequence of a blown head gasket, it is still worrying.

Although a low coolant level may not show up as an immediate problem, aside from making a mess, it can cause serious engine issues if gone unchecked. The other problem is that leaking oil could come into contact with the hot exhaust and create an acrid smoke, possibly leading to a fire.

How to prevent a Head Gasket Failure

To prevent spending thousands of dollars on a cure, it’s better to pay a few dollars for prevention when it comes to head gaskets. The cost of replacing the head gasket itself is not expensive, yet the repair that it requires involves a lot of labor and is pricey, especially for newer cars.

Head gasket issues are generally due to multiple overheating episodes or driving your car after it has already overheated, so the best way to avoid the problem is to make sure your cooling system is functioning properly. If your car starts to boil over, stop and let it cool for at least an hour before you add more radiator fluid.

To check the cooling system, make sure there are no leaks, the radiator is working well, the thermostat opens correctly, and coolant is at an optimum level. Additionally, ensure that the fan (whether mechanic or electric) is functioning properly and has a shroud around it for maximum efficiency.

The best way to detect a head gasket failure is to do a scientific test to see if combustion gasses are present in the cooling system. If there is compression leakage, the gasket is blown. Alternatively, the old mechanic’s trick is to take off the radiator cap, start the car, and search for bubbles in the coolant.

However, these will not show if there are any other failure spots in with the head gasket, so the absence of gasses in the cooling system does not guarantee a healthy head gasket.

Head gaskets of an inferior design can, in some cases, fail due to them not being strong enough for particular uses. This used to be more common with older metal gaskets, which have a limited lifespan due to being exposed to alternating cycles of cold and hot temperatures at every start up. Fortunately, modern MLS (multiple layer steel) replacement gaskets are now available for many scenarios and offer increased dependability than the original gasket design.


So is it time to Scrap your car? Well in most cases this comes down to a combination of factors; 1). the age and general condition of the vehicle 2). the sentimental value of the vehicle 3). If the cost of the repair VS the vehicle value warrants the spend 4). Other challenges the vehicle may have 5). Current MOT status 6). If the vehicle is efficient to run 7). If the vehicle is ULEZ compliant or not if you need to drive into the city.

Over all, its a personal choice, but knowing that you can get a lump sum to put towards a new or used vehicle, with all of the hassle and drama taken away is surely a good think, right? Equally you will know that by using that your vehicle will be recycled in a responsible manner.

Get in touch if you want to find out more: 07472 875 605 or email is on; 

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Colin Tovey

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