Engine failure in cars can happen for a variety of different reasons. The most common reason why an engine would fail is due to lack of routine care. There are components that not only wear down and have to be replaced on a regular basis, fluid levels that have to be checked routinely. Vehicles that aren't maintained properly can cause an engine to fail for a number of reasons.
One reason you should do a routine check is there are many filtering mechanisms on a vehicles engine. These regulate the purity of things like gasoline, air into the carburetor and engine oil. Without changing these regularly they will clog up, making your engine work harder than it has to maintain the same performance. You also have to regularly clean the radiator for both the engine and the transmission.
You have to check fluid levels often. There are many different engine components that require lubrication, coolants and fluids all to maintain a cars performance. More recently made vehicles also have added features like air conditioning units, electronic components, and other things that require even a greater more complex regime. Just checking and maintaining a car's fluid levels either. Build up occurs over time, in the motor, gas tank, radiator, and any other place where deposits will collect. If these systems are not flushed out at least once a year, deposit will build up, making the engine run hotter, and wear out faster.
If a vehicle isn't maintained properly, here just a few of the possible scenarios that can cause engine failure. Too high of a temperature in the motor causes the metal to expand, creating less and less ability for internal components to move. What happens simply is that if your engine gets hot enough for something to stick, like a piston, or a valve, your engine doesn't just stop; the force will cause it to keep going. Something has to give, the side of the motor block, the head, and a number of different ways, depending on where the failure was.
Another way an engine can fail through heat is that when the metal expands, the integrity of the metal itself can be compromised, causing the head to crack or warp. The instant result of this is a sudden loss of engine pressure. Without engine pressure you could have your foot on the gas pedal and only go five miles and hour. You may get lucky on occasion, and only blow a head gasket, or an engine plug. Gaskets and plugs are designed to blow if there is too much heat and pressure, but that doesn't mean that you have done irreparable damage Aluminum heads are especially prone to cracking and warping because they expand a lot faster than as iron cast one.
What can you do to prevent this from happening? While not all engine failure is caused by neglect, you have got to do regular checks, monthly routines, and periodic flushes. This means things like changing spark plugs, wires, and other electrical components on a regular basis. Change and replace filters and motor oil at least according to the minimum requirements by the manufacturer, or more often depending on usage. Flush out fuel systems, brake lines, coolant systems at least once a year. Check your vehicles motor often, maybe at the same time fluid levels are monitored, to see if there are any leaks in hoses, loose belts, or anything else that is out of place. Also make sure that these belts and hoses are still in good working condition, and replace if necessary. Always change out worn belts and hoses all at the same time. If one belt looks worn and needs to be replaced, chances are the other belts may be as well - don't let looks deceive you.
There are many people out there that are unable to do this all themselves. Whether being hurt in an accident, or an older person, or even if someone that isn't mechanically inclined, it still needs to get done. There are several different vehicle services available and many you could find locally. Some offer specialized services, like engine coolant, oil and lubrication specialists. These businesses will check and replace fluids, change filters, as well as many others. Usually they aren't a repair shop so they don't replace hoses belts and the like, but they do check these sometimes as well, and can tell you if something does need replacement.
There are other car specialists that do engine, coolant and heating system flushes, as well as transmissions. Generally, vehicle repair shops are equipped to handle engine and performance issues. They can replace spark plugs, belts, as well as a number of other things.