3 Signs Your Vehicle’s Motor Isn’t Working Efficiently

The Mechanic Doctor – Resources for Amateur and Pro Auto Mechanics

Even after passing away three years ago, Irv Gordon still holds the Guinness World Record for the most miles traveled in a production car. His 1966 Volvo P1800 only had a six-digit odometer, but its total miles counted at 3.2 million. At that mileage, he could’ve circled the Earth 130 times over.

Hardly anyone ever expected a P1800, which ended production in 1973, to last this long. But when asked about the secret, Gordon’s answer was a no-brainer: following the car maker’s maintenance schedule to a T. Take care of the car down to its spark plugs, and it’ll take care of itself for decades. Fortunately, in the U.S., caring for classic cars is as ubiquitous as a national pastime.

Today, accruing over 100,000 miles without major problems is easy. Modern means of design and manufacturing have drastically improved a car’s reliability. The growing consensus among car owners sees no point in buying a new car when the old one still has some life left. This trend rings true for Japanese cars, in which dealers place so much faith in them that they offer warranties for the first seven years or 100,000 miles (whichever comes first).

Still, nothing lasts forever. As cars will eventually show problems, keeping them working beyond their years lies in a mechanic’s capable hands. As soon as the vehicle gets to the shop, the first step involves keeping an eye or ear out for the following signs of potential engine trouble.

Check Engine Light

 For any reason, big or small, the engine light will switch on at the onset of trouble under the hood. Its light can remain steady, and this is usually no cause for concern. But if it’s blinking, that indicates a big problem. Either way, car owners know better not to ignore this warning.

Repair shops use a diagnostic tool called an OBD II scanner to determine the problem that triggered the check engine light. Some of these problems can bn be easily fixed, such as:

  • Faulty Sensors – Oxygen and mass airflow sensors are vital in the combustion process, as they regulate the amount of air and fuel. However, over time, they can accumulate ash from the process and affect vehicle performance.
  • Loose Gas Cap – Sometimes, a check engine light can signal a problem far from the engine, like a loose or faulty gas cap. Without an airtight seal, the gas cap may leak fuel vapor and drastically affect fuel economy.
  • Faulty Spark Plugs And Wiring – When the problem involves spark plugs, most mechanics try to clean them first and see if they’ll still work. If they misfire, these spark plugs would need replacements. At times, faulty wiring can also cause misfires.

There’s More Exhaust Than Normal

Whether gasoline or diesel, modern car engines should be able to burn fuel efficiently. Government regulations limit greenhouse gas emissions produced by a car engine, and this amount decreases every year. However, for a mechanic, a quick look at the exhaust quality is enough to indicate an engine problem.

Combustion generates a slew of greenhouse gases, mostly carbon and nitrogen oxides, but they’re typically invisible. The engine should burn the fuel cleanly, with the toxic gases broken down into less-toxic ones by the catalytic converter. 

Should there be more smoke coming out of the exhaust, it can mean a problem with the combustion process. The type or color of smoke that comes out from your vehicle can indicate varying problems. 

  • White Smoke – While it’s normal for a car to emit this smoke, denser and more consistent white smoke is a troubling sign. It may point to a failed gasket leaking coolant into the engine.
  • Blue Smoke – Typically accompanied by a burning smell, blue smoke signifies oil entering the fuel system and being burned clean. Sometimes, the cause may be that there’s too much oil in the system. Other times, while driving, blue smoke can signify worn-out valve seals or piston rings. For turbo cars, the culprit may be a faulty turbocharger.
  • Grey Smoke – Similar to blue smoke, grey smoke means the engine’s burning oil but this also points to a second problem. The positive crankcase ventilation (PCV), which refeeds unburnt fuel back into the chamber, may have failed. For cars with automatic transmission, grey smoke can also mean transmission fluid leaking into the engine.
  • Black Smoke – Black smoke shows inadequate fuel burn, possibly caused by an unequal mix of fuel and air. The burn leaves soot in the chamber, which produces pitch-black smoke when expelled. It points to issues with the air filter or the particulate filter in diesel vehicles.

Overheating Engine

Car engines prefer to maintain the right temperature when burning fuel, and that’s between 195oF and 220oF. Removing excess heat is the job of the cooling system, which runs the coolant to radiate heat outside the engine compartment. But smoke under the hood and a burning smell can mean that the cooling system’s not working as intended.

The reasons for an overheating engine range from bad to worse, from a clogged coolant hose to a cracked engine block. Without a working cooling system, the excess heat will be trapped and start warping the car’s other metal parts. Engine fluids may also become clogged or get sprayed around the engine block, causing further damage.

Overall, overheating is serious enough to cause total engine failure and write off the whole car. Repairing an overheating engine ranges from fixing any leaks, unclogging, to replacing the whole engine block. It’s not a pretty sight, and the repair costs won’t be cheap either. 


As technology continues to reach greater heights, car engines will grow more reliable and durable. All it takes is to be vigilant enough to look or hear for unusual sounds under the hood. Checking the engine light, observing the amount of exhaust, and knowing signs of overheating are the three basic things to watch out for. These three things should also be routinely observed during general maintenance or a routine car check-up service.


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