78 know what to look for: common engine problems

know what to look for: common engine problems


By Jason Unrau on 2018-07-06 19:06:23

Ever wondered what that noise is you’re hearing from under the bonnet? Maybe you’re curious why your exhaust makes you catch your breath with just one small sniff. Or it might be the nagging little yellow Check Engine Light illuminated on your dashboard that has you worried.

Chances are that what you’re experiencing isn’t all that unusual. Unhealthy for your car? Yes. Bad for the environment? Very likely. But your car isn’t the only one that’s had the certain problem you’re going through. Most running concerns are caused by common engine problems.

Let’s take a look at seven common engine problems. We’ll discuss the symptom you’ll experience, the cause, what the typical repair looks like, and what you can expect if you don’t fix it.

Engine Won’t Start

Turn the key in the ignition the engine turns over. It doesn’t matter how long you hold the key – it won’t start. When you see a car on a tow truck, it’s often what’s caused it to be there, headed to the repair shop.

It can be caused by a plethora of factors. Your engine needs three things to run: air, fuel, and ignition or spark. When one of these three things aren’t present or happens out of sequence, your car won’t start.

It could be a faulty camshaft position sensor or crankshaft position sensor, fouled spark plugs, a fuel pump failure, or about three dozen other causes. And if you don’t fix it – well, let’s just hope you’ve bought a bus pass.

Burning Motor Oil

When you drive, there’s a plume of smoke from your tailpipe. It’s a bluish-white color and it chokes you when you inhale it. Your Check Engine Light has come on, your engine’s starting to misfire, and eventually, your ‘low engine oil’ light will come on.

An engine that’s burning oil has engine oil seeping into the combustion chambers. It could be caused by a leak in the head gasket or it could be coming from underneath, where piston rings aren’t sealing against the cylinder walls very well anymore. It never gets better on its own and can quickly deteriorate from minimal oil consumption to a major issue.

Whatever the reason your car is burning motor oil, it’s no easy fix. It’s guaranteed to be several hours in the hands of a mechanic, and a host of expensive parts. If you don’t have it fixed, though, you could be paying for a replacement engine instead – either because the engine can no longer be rebuilt or because you’ve seized it because you ran it without oil.

Rough Run

You’re at a stop with your foot on the brake, and the engine feels like it’s going to shut off. When you accelerate, it shudders and lacks the power you once had. Again, the Check Engine Light has probably come on.

You probably think, ‘Oh, it just needs a tune-up.’ But that’s not true for modern cars. What you’ll find is that it’s a problem with either ignition, fuel, or air metering. The Check Engine Light is key to isolating the cause.

There may be a shorted ignition coil or the fuel injectors may be plugged. Did the fuel station put diesel into your petrol-powered car? It could even be a timing belt or chain problem. If you choose to ignore the problem, it will get worse. Potential issues can arise from improper ignition such as blown gaskets, overheating catalytic converters, and failed emissions tests.

Stalling Engine

When your engine suddenly turns off while you’re driving or at a stop, it’s considered stalling. There’s one reason your engine stalls, and that’s because of one of the three things an engine need has stopped. Most commonly, the ignition cycle stops occurring but it could also be due to the improper fuel supply.

It will need to be diagnosed by a mechanic to identify the fault precisely. However, it may be the fuel pump isn’t strong enough to supply fuel or is overheating. It can also be a timing problem related to engine sensors. It’s not likely any additional problems will occur due to engine stalling, but it certainly makes you wonder how reliable your car is.

Strong Fuel Smell

With the engine running, there’s a pungent odor emanating from under the hood. It smells like raw petrol. That same odor can come from your tailpipe too, and it’s a separate cause.

Fuel and hot engine parts definitely don’t mix. If there’s fuel from under your car’s hood, it’s probably a fuel leak. Gaskets on the fuel rail, fuel injector seals, or the fuel line itself could be leaking.

A gas smell from the tailpipe is different altogether. That’s a running problem where the engine isn’t burning all the fuel that goes into the combustion chambers. It could be a fuel injector is dumping too much into the engine, a spark plug not igniting, or a timing issue.

It needs to be fixed, no matter what the cause. If a raw fuel smell isn’t repaired right away, it can cause a fire.

Engine Knock

Noises from the engine, while it’s running, can come and go. Those ones are usually no big deal. But if there’s a loud knock-knock-knock that changes with the engine speed, you have a major issue to address. Usually, the closer an engine gets to running temperature, the louder those noises get also.

Engine knock occurs when moving metal components inside the engine contact one another. It may be connecting rod bearings are worn out and there’s a gap that wasn’t previously there.

Engine knock typically develops when an engine has been starved of oil at some point. Without lubrication to protect metal parts, they wear into one another. It can have devastating consequences.

To repair engine knocking, the engine needs to be removed and repaired in most instances. New seals, bearings, and perhaps other hard parts like pistons and connecting rods need to be installed. Left unrepaired, the engine will eventually seize.

Overheating Engine

The temperature gauge has climbed into the red zone. A hissing noise and plume of smoke and steam erupt from under the hood. A sickly sweet smell hits your nostrils. These are signs that your engine is overheating.

It can be from a few different causes: either there’s a blockage in your engine’s cooling system, there’s no circulation, or there’s a leak. Potential issues can be a failed water pump that can’t circulate coolant, a stuck thermostat, a radiator blockage due to corrosion, or a leak from a hose, gasket, or heater core.

Possible repairs could be replacing the cylinder head gasket, changing the thermostat or water pump, detecting and repairing a coolant leak, or even just topping up the coolant for a temporary stopgap. The key to minimizing repair costs when your car is overheating is to shut it down right away. Extended periods of overheating will certainly cause more damage.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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