News and Reviews

How engines really work part three: Engine problems

September, 2013

In our 3-part blog series on how engines really work we’ll get down to the nuts and bolts of what makes your engine rev.

Your car won’t start. That’s what you tell the mechanic, to which he responds with an assault of technical jargon leaving you no more car smart than you were to begin with. Understanding and naming the parts is all well and good – but knowing exactly what can go wrong is better.

Now that you know all about combustion engines and modern engine subsystems, we’ll take a look at what’s really happening under the hood when a common engine problem occurs.

When your car won’t start it usually means there is a problem with the four-stroke cycle. Fuel, spark, or compressions are the major culprits. Don’t forget – when buying a used car; check that these three systems are in great working condition!

A bad fuel mix will create a deficient combustion

An impurity in your fuel, like water in the tank, prevents the fuel from burning efficiently. Otherwise it’s likely something to do with the mix of air and fuel – too little of one or the other means a deficient combustion. In this case the air valve might be clogged or the fuel injector out of sync.

Of course, you could just be out of petrol.

Leaks lead to inadequate compression

The compression occurs after the cylinder is filled with air and fuel injected. If there are issues at this stroke, the combustion won’t occur like it should. Basically what it comes down to is leaks.

A leak can occur when the piston rings are worn, or the intake and exhaust valves are not properly sealed. The cylinder and cylinder head are held together by a gasket. A worn out gasket can also create leaks – your mechanic might refer to these as cylinder holes.

No spark, no combustion at all

The spark is what makes the combustion stroke happen, so a poorly timed, weak or non-existent spark means you won’t be going far. You could have major problems if the ignition timing is off and the spark occurs too late or too early within the four-stroke cycle. If the wire is worn out, you’ll only get a weak spark and if the wire is cut there will be no spark at all.

That concludes our 3-part master class on how engines really work. With a little bit of engine education under your belt, trips to the mechanic and roadside breakdowns should be a little less stressful for all involved.

Read part one and part two.

Do you have any tips for preventing engine problems? Let us know in the comments! 

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