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About This Quiz
Do you regularly whisper to car engines? Are people constantly asking you to help them figure out what's wrong with their ride?ÂÂ
Being able to diagnose engine problems requires you to first know a lot about engines. After all, you can't figure out the cause of a problem if you don't know how things run. Most people know how to diagnose a few simple problems, but being able to correctly diagnose all kinds of engine trouble requires a huge amount of practical knowledge.ÂÂ
More modern engines often require even more knowledge and equipment to properly diagnose. While a shop can hook the car up to diagnostic equipment and pinpoint a problem with ease, some issues still require mechanics to act like detectives. There are always strange, obscure and particularly vexing engine problems out there, which can puzzle even some of the most experienced in the field. These are often the subjects of discussion on automotive radio shows, forums and websites for mechanics.ÂÂ
How would you fare at diagnosing engine problems? Are you a pro? Take the quiz now to find out!ÂÂ
What causes the exhaust to always look white and smell sweet?
extra rich mixture
coolant leaking into the cylinders
Combusting coolant can be from a few different problems. One of the most common is a blown head gasket, but a cracked engine block is another possibility.
too lean of a mixture
improper spark plug gapping
What causes an engine to stumble when you press on the accelerator at freeway speeds?
too much air is flowing into the engine
not enough fuel is making it to the cylinders
the engine is misfiring
all three issues
A lean mix, where you have too little fuel in relation to the amount of air, will cause an engine to stumble in these kinds of conditions. The root of this problem can be in the fuel, air intake or ignition systems.
Why would the engine make a rapid clicking noise but not start up?
The fuel filter is clogged.
The spark plugs slipped a gap.
There's a fault in the ignition system.
While most people jump to the conclusion that the battery is bad, this problem could be caused by a bad alternator, blown fuse or other issue with the ignition system.
The battery exploded.
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Why would the traction control and stability control lights come on and stay on after you start up your car?
Your tires are too worn.
The tires are slipping too much.
There's a fault recorded by the ECU.
While there is a possibility you turned these two systems off by pressing buttons in the car, the more likely scenario is there's a fault the ECU detected and you need to have the engine codes read.
The engine threw a rod.
What causes flames to shoot out the tailpipe?
too lean of a mixture
too rich of a mix
If there's way too much fuel being dumped into the cylinders, the unburnt fuel will make its way into the exhaust system where it will then combust, shooting flames out of the tailpipe.
a balanced mix
a bad cat
Why would the spark plugs have a white material on them?
The engine has been overheating.
Excessive heat will make spark plugs appear this way, which can be from an overheating engine. A lean fuel mixture or improper ignition timing will also cause this problem.
The gas has crystallized in the tank.
You tightened them too much.
You didn't seal the electrodes properly.
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What's wrong with the engine if it squeals on startup?
The cat got in it.
A belt or pulley is worn.
Squealing is most often a worn or loose belt, but most people fail to realize the pulleys might also be worn and need to be replaced, or the squealing will continue.
The distributor is going bad.
Compression is too low.
What can cause a faint ticking sound to be coming from an engine?
You dropped your watch in the engine bay
The oil pump is failing
Ticking in your engine is likely coming from the valve train, with oil issues such as a dying pump being perhaps the worst of the potential causes.
The valves need to be cleaned
The timing is incorrect
What's wrong with the engine if you start seeing blue smoke coming from the exhaust?
The O2 sensor is out.
The MAF is blown.
It's burning oil.
Any blue smoke in your exhaust is a sign that oil is making its way into the combustion chambers. The source could be a number of components, like the piston rings or valve guide seals.
The exhaust gasket is leaking.
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What might cause a pinging sound coming from the engine after you've turned it off?
detonation
retarded timing
advanced timing
cooling heat shields
While some people might try to tell you this is detonation, that can only happen when the engine is running. Instead, the sound is the metal on the heat shields contracting, and maybe a few other components, depending on the engine.
What does it mean when the spark plugs are coated with a black liquid?
The electrodes exploded.
Oil is getting into the cylinders.
There are a number of ways oil could be getting into the combustion chambers, like worn piston rings, a cracked piston or old valve guides, to name a few.
The distributor is bad.
The ignition wires are burned out.
If you notice the engine vibrates more than usual when you accelerate, what's likely the cause?
serial harmonizer
worn/broken engine mounts
The engine mounts are designed to soak up vibrations from the engine, especially when the engine is under load. If they wear out, you'll notice they don't perform that job as well.
bad camshafts
a bent tie rod
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What is the first thing you should check if your engine starts running hotter than normal?
coolant level
Always use caution when checking the coolant on a hot engine, especially if the overflow reservoir is pressurized, since the coolant could spurt out and burn you.
oil level
the engine fan
the AC setting
What's the reason for black exhaust smoke?
The catalytic converter is burned out
You need to change the oil
It's burning too much fuel
There are a few possible causes for this problem, including a clogged air filter, malfunctioning air temperature sensor, malfunctioning MAF, clogged fuel injectors or a malfunctioning fuel pressure regulator.
The engine is burning oil
What could cause the engine RPMs to race as a car is idling?
the wrong kind of gas
the wrong weight of oil
too thin of air
there are several possibilities
The fact is that engines can surge when the car's just sitting because of several possible issues, like a problem with the EGR valve, a vacuum leak, too lean of a mixture, or the idle air control motor going bad.
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What does it mean if there are dry, black deposits on the spark plugs?
Your air filter is too dirty.
You need a new alternator.
The spark plugs were overtightened.
a weak spark or rich mix
Any number of issues could lead to either cause of this symptom, including a leaking fuel injector, bad oxygen sensor, too high of resistance in the spark plug wires, or a bad distributor, to name a few.
An engine stalls out under load. What's one possible cause?
The O2 sensor is bad.
clogged fuel injectors
For an engine to run properly, it needs the proper amount of fuel and air, plus the timing or spark needs to be correct. If any of these elements are off, it can stall.
The gas cap is cracked.
The oil level is too high.
Steam pours out from under the hood, and it smells sweet. What's the most likely problem?
dirty oil
a loose oil cap
a malfunctioning O2 sensor
low coolant
If the coolant level becomes too low, the engine will overheat and it will boil the coolant, which generates the sweet steam. A broken engine fan, problems with the radiator and even a bad thermostat can also cause this.
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What does it mean if the engine starts rattling and the oil light comes on?
The engine is suffering oil starvation.
Oil starvation is a serious issue that can have its roots in one of several possible conditions. The most likely cause is that the oil level is low, maybe because of an oil leak you'll need to fix.
The evap system is faulty.
You need to use better gas.
A spark plug has come loose.
If a whining sound is coming from the engine compartment as a car is running, what could that be from?
the cat
a faulty oxygen sensor
bad pistons
power steering pump
The first thing you should check is the power steering fluid level. If it's low, top it off and keep an eye on it. The power steering pump could be going bad, or the issue might be a belt or pulley.
What does a loud knocking noise while an engine is running possibly indicate?
a thrown rod
loose valve seals
detonation
Explosions happen in your engine all the time, but when they occur before they should the result could be serious damage. Fixing engine knock can include methods like using a different octane fuel, retarding the ignition timing or changing the compression ratio.
imbalanced camshafts
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What does gray exhaust smoke indicate about a car?
It needs a tune-up.
stuck PCV valve
The Positive Crankcase Ventilation (PCV) valve helps release pressure in the crankcase. If the valve becomes stuck, the building pressure leads to oil leaks and gray exhaust. The other possibility is the engine has been burning automatic transmission fluid.
The valves aren't clearing.
Your injectors are clogged.
What does a chipped or even split spark plug insulator mean?
You screwed it in too tight.
The engine is running lean.
The oil level is too low.
The engine is experiencing spark knock.
The cause of the dreaded spark knock or pre-detonation is usually a faulty EGR valve, clogs in the combustion chamber, timing that's off or overheating.
The oil light flashes irregularly, but only for an instant. What's the reason?
a short in the circuit box
low oil
The first thing you should do is check the oil level immediately and top it off. A bad oil pressure sensor is possible, and that's something that should be fixed quickly.
a fuse is melting
nothing
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What would cause the heater to stop working suddenly, but air still blows out of the vents?
AC lost its charge
a blown fuse
low coolant
You might think coolant is something that's only useful in the warmer months, but the fact is the stuff is what powers your heater. Top off the coolant level and your heater should start working just fine again.
dirty oil
What could cause the spark plug electrodes to be broken or flattened?
Turbo compression is turned up too high.
They're too long for the engine.
You always need to double-check that the spark plugs you buy for an engine are actually designed to fit in that engine. If they're too long, they can come into contact with the pistons and cause serious damage.
The engine's timing is off.
The engine is low on coolant.
What causes an engine to idle rough?
dirty fuel injectors
dirty air filter
bad spark plugs
all of these
Rough idle is often caused by one of the issues already named, as well as issues with the ignition wires, coils, PCV valve, EGR valve, oxygen sensor and even vacuum leaks.
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After installing a new battery, the engine keeps stalling. What could be the reason?
The battery is bad.
The ECU settings were reset.
The ECU or engine control unit manages all kinds of factors that affect how the engine runs. As the engine ages, the ECU makes adjustments so everything operates smoothly. Replacing the battery might have changed the settings to factory presets, which are great for a brand new vehicle.
The negative terminal is loose.
The battery cables are installed incorrectly.
Why would an engine idle too high or too low?
The intake screw is loose.
the air conditioning cycling
a dirty air filter
There are several possible causes.
Thanks to the complexity of modern engines, a whole range of problems can cause a high or low idle, like an issue with the idle control valve, a vacuum leak, a failed intake gasket or a faulty PCV valve.
If you pull the dipstick out to measure the oil level, and there's a milky white substance clinging to it, what could that mean?
The oil is overheating.
Coolant has mixed with the oil.
A blown head gasket is the most common reason for this issue, but there are other possibilities, such as a cracked engine block.
The oil is the wrong brand.
The weather is too humid for running a car.
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What's the origin of a red fluid leaking from the engine compartment?
old oil
the air conditioning
transmission or power steering pump
Manufacturers dye transmission fluid red so it's easy to spot. In some cars, the power steering pump uses transmission fluid, so it could be the source.
the radiator
What would cause an engine to suddenly lose a significant amount of power?
no air filter
bad fuel pump
Your engine needs the proper amount of fuel, or it won't make enough power. If the fuel pump suddenly has problems, you'll notice an immediate difference in performance.
old oil
a blown ECU
Why would a car start bucking or jerking violently, instead of accelerating and slowing smoothly?
clogged air filter
bad throttle position sensor
If the throttle position sensor fails in a certain way, it can send a sporadic signal to the ECU, resulting in the bucking or jerking.
loose oil cap
loose ignition wire
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What will cause a clear, colorless and odorless liquid to leak under the engine after the car has been parked?
condensation from the AC
As you run the air conditioning, condensation builds in the system, which then runs out and will pool under the car if it's parked. This isn't a cause for alarm.
power steering leak
coolant leak
nothing
If you check the coolant reservoir and there are dark swirls in it, what's the cause?
rusting radiator
oil pollution
If everything on your car is running perfectly, the oil and coolant never get close to each other. But, if there's a problem like a blow head gasket, these two fluids can mix, resulting in such weirdness.
bad coolant lines
overheating central heating core
You Got:
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