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10 Signs You Need a Car Engine Rebuild

Marc Skirvin
Marc Skirvin

What's in this Article

The prospect of a faulty vehicle provokes anxiety for several reasons.

First, there’s the inconvenience of dealing with it when you’ve got work or a social appointment. Then there’s the most important aspect — safety and health.

Rebuilding old engines may be annoying for scheduling purposes, but delaying your car engine rebuild leads to worse circumstances. It’s far better to deal with your issues on your own time before a worse problem disrupts your livelihood.

So keep reading for ten signs you need a car engine rebuild. We’ll let you know whether these mechanical fixes are necessary.

1. Car Running While Off

With a faulty engine, sometimes a vehicle continues to run even when turned off. Even when completely turned off during ignition, it still continues to operate.

Not only is this obnoxious, but it’s dangerous too. Neglecting this problem until it’s too late could have lethal consequences.

What if you park on a slope? What if there’s someone around that’s too distracted to avoid a running car where it shouldn’t be?

All engine problems must be fixed immediately, but this one is one of the more pressing issues. Whether the issue involves a failing engine solenoid or carburetor issue, professional service is definitely needed.

2. Stalling

On the other hand, it’s possible for your car to stall while it is on. While driving, you should be the one in control, not the car. But sometimes, faulty engines can cause your car to randomly stall, resulting in an awkward traffic standstill.

This standstill could be lethal too, depending on the circumstances. Sure, in most cases, stalling is just awkward and exasperating for those around you. But stalling could mean something worse, such as a giant car pile-up and/or injury to you and others.

3. Strangely Colored Smoke

A noticeable rise in smoke production is a heavy indication of car engine damage. If your car produces an unusual amount of smoke, there’s probably something wrong with the motor.

Most likely, while smoke production has increased, the color of the smoke is also discolored. Understanding the reasons smoke takes on different colors can help you diagnose the problem.

White Smoke

White smoke indicates problems with your coolant. More specifically, coolant and water have leaked and burned into the combustion chamber. Burning this combination of substances creates an opaque, white smoke.

Damage to the cylinder head and burst head gaskets are common culprits for white smoke. To confirm your suspicions, you can check for color and consistency shifts of the oil. Check if the oil is gluey, gooey, and brown — if it has, then your coolant and engine oil have most likely mixed together.

Black Smoke

Black smoke looks much more threatening than it actually is. Most likely, black smoke means that there’s an imbalanced fuel/air ratio. Specifically, there’s too little oxygen able to combine with the fuel, resulting in black-colored smoke.

Blue Smoke

Blue smoke usually points to burning engine oil. Usually, this happens through loose parts or run-of-the-mill tears and cracks within the engine. These gaps create paths for engine oil to easily slip through to places where it shouldn’t be.

Loosened parts that usually bind engine parts together could also cause burning engine oil. These parts usually loosen through aging, and might not be detected without the help of a professional.

4. Leaking

Notice any leaking fluids, especially from the front of your car? If you do, understand that you might be lucky enough to fix damage before it gets worse.

Coolant and other fluid leaks indicate that your engine isn’t in good health. Before these leaks transform into worse problems, patch them up. The health of your combustion chamber might depend on it.

5. Check Engine Light is On

Of course, your car will lend the most obvious indication of damage through its engine light. But without professional expertise, this is as far as your diagnostic skills go.

Beyond the light, there’s not much specification as to what the problem actually is. Unless there’s an obvious sign such as strangely-colored smoke and leaking, it’s best to let a professional handle this issue.

Upon initial inspection, professionals usually detect a handful of common issues. Again, there are many reasons that aren’t specific to one area. But understanding these common problems can let you know what to expect from a diagnosis.

Failing Oxygen Sensor

If your car’s oxygen sensor fails, you’re most likely also experiencing lower fuel efficiency. In that case, you must contact a professional technician to take a look at your car. Doing so can prevent you from paying hefty gas fees in the future.

Loose Fuel Cap

A loosened fuel cap can threaten your car’s ability to circulate fuel. With proper circulation, gas fumes don’t escape the fuel tank, which should be well-pressurized.

This is usually a fairly minor issue. Sometimes all that’s needed is a new fuel cap and turning your car off and on.

Failing Catalytic Converter

As opposed to loose fuel caps, catalytic converter failures are much more severe. These failures tend to happen when other previous engine failures accumulate, especially those that operate with the converter.

After this discovery, it’s time to stop skipping out on professional service. It’s better to get your converter up and running again than to put yourself and others in danger in the event of total engine failure.

6. Fuel Inefficiency

Check out your engine if you’re spending more on car gas, especially when general gas prices are relatively stable. Different gas stations have varying levels of gas quality, but a continuous rise in gas usage indicates that your fuel isn’t being put to good use.

It’s possible that your car is just old. Engines in old cars are bound to break down after years or decades of use, even after a long period of reliability. Nonetheless, it’s best to double-check with a professional that will give you a more precise diagnostic answer.

7. Knocking Noises

Loud, uncharacteristic noises from your car should always cause concern. But if you hear knocking and banging, then there’s definitely something wrong with your engine.

If this noise occurs, it will worsen through strenuous tasks. When navigating a slope or dealing with rough terrain, this noise will get even louder as your car works harder to operate.

Most likely, this issue lies at the bottom of your engine, usually from something like a loose bearing. This bearing is necessary to tighten the operation of your car’s pistons and crankshaft.

This mechanism is crucial to keep under control. Letting this issue persist will only cause damage to worsen, blowing what could have been a modest engine rebuild budget.

8. Engine Odors

If you are experiencing loud knocking noises from your engine, you’ll most likely experience the smells too. These unfortunate odors are the result of a faulty engine, creating unpleasant reactions from your combustion chamber.

These odors are also terrible for both you, the environment, and everyone around you. They are also especially concerning for those with respiratory conditions or those with loved ones that do.

There are different types of engine odors, and understanding what you’re smelling can help you specify the problem. But a mechanic is trained in both their terminology and their smells and can help distinguish different smells from each other a lot better.

9. Sludge on Oil Pin

Any extraneous goop, smells, and fluids all indicate bad engine health. Finding brown sludge on your oil pin is no exception.

If sludge has tainted your oil and coolant, then the engine must be rebuilt. These fluids are now ineffective, and the sludge can cake on to worsen problems for the future.

10. Complete Shutdown

Of course, the biggest telltale sign that anything’s done working — complete system failure. When this happens, there aren’t any Band-Aid solutions left.

While you’ve probably ignored many symptoms of engine failure by now, a complete shutdown is an ultimate consequence. However, it’s still advised to go to a professional, who will let you know if saving the engine is viable.

Do You Need a Car Engine Rebuild?

Car problems are more than culprits of work tardiness. They’re also the cause of many traffic accidents and deaths, and can also make financial problems worse if not fixed as soon as possible. While a car engine rebuild might seem like a hassle, dealing with worsening problems is a bigger one.

At Cash Auto Salvage, we understand that cars don’t last forever. That’s why we buy used cars, offering financial boosts as quickly as you need them. So if you have car problems you want to get rid of, get your cash offer on your used car today!

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About the Author


Marc is the Co-Founder of Cash Auto Salvage and Director of daily operations. He retired from a leading Internet Marketing company in 2013 and has been involved in the automotive industry ever since.

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