What are the signs of a blown head gasket and how do you deal with the fallout?
We have all heard the term before, but not everyone knows what a head gasket is and what purpose it serves. At the same time, the idea of a blown head gasket induces fear in even the most enthusiastic of gearheads, as the effects of a head gasket failing can be far-reaching. In this discussion, we look at what a head gasket is and how it functions, as well as what the symptoms are when it's not doing its job anymore.
Firstly, a head gasket forms a seal between the engine block and cylinder head. The engine block contains the crankshaft and pistons, and the engine head contains the valves that let air into the engine, the spark plugs, and the fuel injectors. The camshaft can be block- or head-mounted. An engine head cover with its own gasket goes on top of the cylinder head to cover the valve gear.
There are coolant passages that run through the engine block to the cylinder head, which also pass through the head gasket, with the aim of keeping the engine at the right temperature. The second function of the head gasket is to restrict the coolant flow between the cylinder head and the block, so the openings on the head gasket that line up with the coolant passages are smaller in size. It is also designed to prevent oil and coolant from mixing.
The third function of a head gasket is to account for differences in expansion between the engine block and cylinder head, preventing leaks. In the same way, the gasket mitigates any unevenness on the engine block, preventing leaks between pistons, or leaks to the outside of the engine block.
It has to be strong enough to withstand the forces of the combustion pressure while maintaining a positive seal. If this seal is breached, a head gasket leak develops and we say that the head gasket has "blown". This could cause the mixing of oil and coolant. If a blown head gasket sounds serious, it's because it is.
Let's discuss some of the causes of a blown head gasket, and what signs of a blown head gasket to look out for.
The main causes of the typical head gasket leak symptoms include:
These are the possible symptoms of a bad or blown head gasket:
Knowing this, can you drive with a blown head gasket? The engine might keep going, but it could misfire, run roughly, overheat, or cause long-term damage. You may experience a significant loss of power, meaning you can't drive at all. Depending on the severity of the gasket damage, you may be driving with a leaking gasket without even knowing it, which is why routine checks and maintenance are so important.
Ideally, it should be repaired as soon as possible to avoid major damage. Remember, with oil and coolant not being able to do their jobs, the entire engine is compromised. No longer able to effectively lubricate and cool the engine, it may actually seize up entirely, prompting an expensive engine block repair or replacement.
You may be asking for tricks on how to fix a blown head gasket without replacing it, and while many temporary repair kits are advertised, we caution against it. Minor leaks and slight wear and tear can be temporarily dealt with, but there's no real quick fix for a blown head gasket.
A far better option is to replace the gasket. Although it is possible to do this yourself if you have the know-how, tools, and equipment, it's not a small job at all. How to replace a head gasket is no simple task - we strongly advise you to get professional assistance in this regard.
A properly maintained car in normal use will rarely suffer a blown gasket. However, this useful guide will help you identify a blown gasket, should it happen to you. Whatever you do, never ignore it - it is possible to identify minor leaks before it becomes too serious, so remember to regularly check your engine bay and ensure routine maintenance is done. If you do find yourself in a situation that requires a replacement, rather spend the money to get the gasket replaced than taking shortcuts - it's still cheaper than replacing the engine.
A head gasket's price varies a lot - from as little as ten to a few hundred dollars at most. The big expense is labor for stripping the engine, replacing the gasket, flushing the cooling system, and reassembly. This could be less than $1,000 on a small four-cylinder engine, but thousands of dollars on complicated cars.
Best-case scenario, yes, but a competent mechanic would check for other damage. Severe overheating can crack a cylinder head, necessitating its replacement. Driving with a blown gasket can ruin the engine. Have a mechanic check for other damage and what it would cost to fix.
Internal combustion engines (ICEs) all have head gaskets. Inline engines have one cylinder head and gasket, but V engines have two - one for each cylinder head. An electric vehicle doesn't have an ICE and, therefore, no head gasket.
Fill the cooling system with the correct blend of water and antifreeze and ensure the system is always topped up - acidic coolant eats away at the gasket material. Properly maintain your engine and regularly check its fluids. Don't exert the engine beyond its limits; rather buy a diesel SUV with lots of torque for towing big rigs instead of stressing the family minivan to do it. Read more here on how to choose between SUVs and minivans. The best crossover SUVs usually have better tow ratings than cars - important information if you tow. For example, an Acura MDX crossover can tow up to 5,000 pounds, while the Acura TLX sedan isn't rated to tow at all.