Buying a Used Car? 4 Engine Health Checks  Do

Embarking on the journey of shopping for a used car necessitates a meticulous examination under the hood to ensure the engine is in robust condition – a critical step to avoid the seven deadly automotive sins that may manifest as unforeseen problems and lead to hefty repair bills.

 As someone who has encountered the allure of a seemingly cheap ride, I emphasize that the label “used” doesn’t inherently imply unreliability; my own positive experience involves a vehicle that defied expectations. While test driving a car, the paradoxical notion that a near-silent engine might betray a well-cared-for vehicle should be kept in mind. 

Finally, conducting a back-of-your-mind check during the inspection ensures that potential issues lurking beneath the surface won’t result in a costly breakdown waiting to happen. Remember, a well-maintained engine not only safeguards against future pains but also allows for a joyous and wallet-friendly automotive journey.

1.Start with the Service History

When considering the purchase of a car, delving into its service history is paramount. The maintenance work and care the engine has received over time can unveil areas of concern or reassure potential buyers. Whether it’s inspecting the logbook for recent fixes, ensuring no maintenance work is incomplete, or deciphering the schedule of routine service, a detailed examination of the service history can be a sign of a healthy vehicle. However, one must be wary of signs that the current owner might be deliberately hiding past issues to make the sale more appealing.

Check for spots, drips and puddles underneath the car

Kneeling down and taking a closer look underneath the car can be like a detective’s work. From spots and drips to more concerning puddles, it’s crucial to figure out their origin. A seasoned eye can differentiate between age-old oil streaks and fresh spots. An active drip or a puddle filling above might indicate a deal breaker. A car accidentally parked over an old spill could be losing precious fluids. A watchful inspection of these areas can reveal potential problems and save you from a host of headaches down the road.

Hire an experienced technician for inspection

For a more in-depth analysis, hiring a professional technician becomes imperative. These experts can spot hidden mechanical abnormalities that may elude the untrained eye. Whether you’re eyeing a used vehicle from dealers or private owners, a professional inspection can tell tales of oil seepage and other issues. Some car makes and models are notorious for leaking oil, making it worth occasionally adding oil. A knowledgeable buyer is an empowered buyer.

Identify what type of fluid any puddles are made from

Not all leaks are created equal, and identifying the type of fluid from brake lines, cooling systems, or transmissions is crucial. A simple finger poke into a wet spot can reveal whether it’s reddish, black, caramel, green, or even orange fluid. Clear puddles might just be water or oil-based. Being mindful of recent weather conditions, like rain, is essential. Paying attention to these steps can help you decode the language of your car’s leaks.

Inspect the undercarriage

A thorough examination of the undercarriage is like peering into the car’s soul. From the engine compartment to the underbelly, you must scrutinize for puddles, clean spots, road grime, and greasy residues. Dark spots, drips, and clumps can indicate various issues. A seller might have overlooked or deliberately hidden problems, but a keen eye with a paper towel can reveal the truth. Don’t hesitate to poke around and hose down areas to better expect any hidden surprises.

Decide whether leaking is a problem for you

Drips, runs, and wet sludge are red flags, but the real question is whether the leakiness is a problem for you. In a car full of options, it’s crucial to decide if the leaks are a deal-breaker or something you can address. Ignoring leaks may lead to significant losses and progressively worse problems. Preventing them from the start is the key to a confident purchase. If a car has obviously been leaking and caked over with sludge, it might be a sign of potential engine problems that are best ruled out early.

Cold Start the Car

One of the simplest ways to catch hidden engine faults is to perform a cold start. This can reveal underlying problems that might not surface during regular operation. Listen for any strange rattling noises, check for a struggling timing belt or drivetrain, and inspect the exhaust for smoky fumes. A true cold start, especially when arranged by the seller or dealer, provides a genuine view of the car’s health. Don’t just rely on a warm start when you arrive; insist on experiencing the car from its coldest point. Your future self will thank you.

2.Recognise the Signs of Poor Maintenance

In the pursuit of a well-maintained vehicle, it is crucial to recognize the subtle signs that indicate the level of care the engine has received. Popping the hood unveils a world that goes beyond the shiny exterior – an engine that might have been meticulously looked after or, conversely, one that bears the scars of neglect. As an enthusiast, I highly recommend inspecting the engine compartment thoroughly to uncover potential issues.

Pop the Hood and Take Note of Any Smells Coming from the Engine

Before even engaging with the seller, take a moment to lift the bonnet and inhale. A pristine, shiny appearance might disguise underlying problems. An old car’s engine could emit various smells, from gas-imbued fumes to a distinct odor of burning. These warning signs could be indicative of fuel system leaks or issues within the cooling system. Don’t be afraid to use your nose – it’s an invaluable tool in assessing the condition of the engine.

Take a Long Look at Your Engine Compartment and Its Contents

A courteous seller might go the extra mile to make the engine compartment look nice, but it’s crucial to look beyond the surface. Evidence of leaks or a dirt-covered engine could tell a tale of a car that hasn’t been well-maintained. Cobwebs and sludge-caked components might indicate a need for new gaskets or, in extreme cases, an engine rebuild. Don’t be fooled by a clean spot; it might just hide an otherwise dirty engine.

Check the Fluid Levels

Ensuring optimal fluid levels is a fundamental step in assessing the health of a vehicle. Stumbling upon low oil levels during a dipstick check could be a sign of potential problems down the road. Checking transmission fluid, power steering fluid, brake fluids, and coolant levels provides a comprehensive view of the vehicle’s overall condition. A low level might not be a deal-breaker, but it’s essential to note and assess before making a purchase.

Inspect the Belts and Hoses

Engage with the seller and inquire about the last time the car’s belts and hoses were replaced. A keen inspection might reveal cracks in the rubber parts, indicating that they need replacement soon. Squeezing hoses and plucking at belts can be a hands-on way to assess their condition. Overlooking these critical components might lead to problems such as a car that won’t start or issues with essential functions like A/C and power steering.

Inspect the Battery and Terminals

Much like the engine, batteries and their cables can appear clean and still harbor issues. Cracked, leaking batteries or exposed cables with green or white residue are warning signs. While they might clean up nice, hidden problems could emerge, affecting the car’s overall performance. A simple jump start might not address these underlying issues, emphasizing the importance of a thorough inspection.

Ask About the Air Filters

When buying a car, inquire about the status of the air filters. Clean and new filters contribute to the efficient performance of the vehicle. If the air filter appears old and dirty, it may need replacing. Checking and replacing filters for oil, gas, and the cabin air is a wise step to ensure the longevity and efficiency of the engine.

Make Sure the Turbo Is Connected and Not Rusty

For cars equipped with a turbocharger, a thorough examination is necessary. Diagnosing running issues, checking for leaks, and ensuring the turbo is connected and not rusty are crucial steps. Turbos are intricate components that, if neglected, can lead to significant performance problems. A detailed inspection ensures that this vital part of the engine is in optimal condition.

Step Back and Look at the Engine Compartment as a Whole

After inspecting individual components, take a step back for a wide view of the engine compartment. Different makes and models might have a unique setup, and it’s essential to observe the various goings-on. Whether it’s loose wires, hoses, or potential missing parts, a comprehensive view can reveal the overall condition of the engine. This step is particularly crucial for newer cars with complicated electronic systems.

Check the Colour of the Exhaust Fumes

The color and smell of exhaust fumes during a test drive provide valuable insights into the engine’s condition. While gray-white smoke is typical, blue or black smoke might indicate burning oil or a problem with the fuel mixture. Ignoring the condition of the exhaust fumes could lead to a costly repair bill down the line.

3. Making the Final Checks

Examine the Exhaust Pipe

When it comes to understanding the health of your car, don’t overlook the exhaust pipe. The tailpipe will offer clues about the engine’s condition. An ashy gray residue might just be a sign of normal operation, while black soot can hint at the engine running rich – an imbalance in the gas and air/fuel mix that can lead to poor fuel economy. Conversely, white tips may indicate a lean mixture, causing increased wear and tear on the engine. Modern vehicles rely on sophisticated electronics, like the O2 sensor and airflow sensor, to prevent these issues, but an older car may signal the need for a check on timing or valve adjustment.

Figure Out Why the Car Won’t Start

Have you ever turned the key and nothing happened? No dash lights, no sound – it could be a dead battery or bad connection. Check for corroded terminals and ensure that cables are connected and tight. Sometimes, spilling soda might call for a cleanup to ensure contact is present. If dash lights come on but the engine doesn’t start, you might simply need to charge the battery or use jumper cables. If the engine turns over but still won’t start, don’t stomp on the gas pedal right away. Instead, wait a few seconds, then try again. If it’s been a while since the car was last started, it’s likely the fuel hasn’t been pumped to where it needs to be.

Take a Look at Your Spark Plug Wires

The spark plug wires play a pivotal role. If they’re loose, your car might not start at all. Make sure each one is snug. If it still won’t start, you might need to pull the wires and clean them. If your car has a carburetor, dumping a few teaspoons of gas into the venturi can sometimes get things moving. For a car that has been parked for an extended period, say one you’re planning to sell, it’s crucial to start it up every so often. If that doesn’t happen, recurrent problems are almost guaranteed.

Listen to the Sound of the Engine Once You Get It Running

If you finally get the car running, listen to the sound of the engine. A smooth purr is good news, but any wheezing, clicking, or knocking sounds signal trouble. The rapid Tic could point to sticky lifters or loose valves, while a Knock noise when the engine’s RPMs are ramped up could mean a serious engine knock. And Squealing? Likely a belt issue. Some noises may disappear once the engine is warm which could simply imply a belt change is needed. Scraping noises should make you extra mindful; they often herald major issues.

Bring the Car for a Test Drive

After all the noises have been addressed, it’s time to hit the road for a test drive. Drive to your local auto parts store and use their services to connect a code reader, checking for any hidden issues – a useful step especially for cars from the ’80s or newer. Pay attention to any distinct lack of power or odd shuddering as this will help in diagnosing any hiccups. Post-drive, you may want to consult a mechanic or parts guy for further diagnostic help, especially if you’ve noticed anything off.

Assess the Car’s Idle Noise and Feel

Finally, letting the car idle gives you a sense of its general health. Ensure it idles smoothly and stable without hesitation or lulls in power which could indicate issues such as low battery or improper ignition timing. Pay attention to any unusual vibration or knocking – signs that it’s time to check the engine oil or that there might be serious issues to address. All the while, keep an eye on the temperature gauge for any signs of overheating.

With these checks, even an old vehicle can reveal its secrets. Assessing a potential purchase or just maintaining your trusty ride requires a meticulous eye, but it’s a rewarding process. Every car has a story to tell through its nuts and bolts, and with a bit of expertise, you can read it like a book.

4 .If in Doubt, Take an Expert Along

When diving into the realm of purchasing a used car, exuding confidence is crucial. Doubt can transform the excitement of acquiring a new set of wheels into a potential heap of trouble, complete with unexpected repair bills.

 Drawing from personal experience, having a knowledgeable friend or relative by your side not only provides peace of mind but also ensures a thorough inspection under the bonnet. Their expertise can discern between a good engine and a disaster waiting to happen. This commitment to bringing an expert along is more than just a precaution; it’s a practical tip that can elevate the overall performance of your investment. 

Consider exploring Redex’s range of products to potentially save on future maintenance costs and improve your chosen vehicle’s longevity. With the right support, the journey of buying a used car becomes a collaborative adventure, guaranteeing a better drive and steering clear of any unwanted surprises in the process.


In conclusion, the process of buying a used car demands a meticulous approach to ensure the engine’s health and avoid unforeseen issues and repair bills. As someone who has experienced the allure of seemingly cheap rides, I emphasize that the label “used” doesn’t inherently imply unreliability. 

A thorough examination under the hood, guided by the five engine health checks, can unravel the true story of a vehicle. Whether it’s assessing the service history, inspecting for leaks, hiring an experienced technician, recognizing signs of poor maintenance, or making final checks, each step contributes to a comprehensive understanding of the car’s condition. Remember, a well-maintained engine not only safeguards against future pains but also allows for a joyous and wallet-friendly automotive journey. 

And when in doubt, taking an expert along becomes not just a precaution but a practical tip that elevates the overall performance of your investment, ensuring a smoother drive and steering clear of unwanted surprises. With these insights and checks, the journey of buying a used car becomes a collaborative adventure, guaranteeing a better drive and peace of mind.


How do you inspect a used engine before buying?

Check for any cracks, leaks, or other damage to the engine block. Make sure all the bolts and nuts are secure and tight. Check the oil and coolant levels to ensure they are at the right levels. If the levels are low, it may indicate that the engine has not been properly maintained.

How do you check the health of a car engine?

  • Check Engine Oil Level and Condition. 
  • Check the Cooling System. 
  • Battery Check. 
  • Drive Belt Inspection. 
  • Check the exhaust system

What engine check should you make when considering purchasing a used car?

Look under the hood for obvious signs of wear. First, make sure the engine doesn’t appear to have fluid leaks dirtying the block. Do a quick oil check to see that it isn’t murky, and also inspect transmission fluid levels. Feel any rubber hoses and belts to make sure they aren’t cracking or super stiff.

Is it safe to buy a used engine?

Reliability – A used engine or transmission isn’t likely to be as reliable as a new or remanufactured engine. Any drivetrain component is only as good as how well it was maintained, and with used components, you rarely know the maintenance history of that vehicle.

Should I buy an engine from a junkyard?

While some junkyard engines may still be in good working condition, there is always a risk of hidden issues or wear and tear. It’s important to thoroughly inspect and research any junkyard engine before purchasing it, and consider having a professional mechanic assess its condition.

How do you tell if an engine has been well maintained?

Ensure you ask for the vehicle’s service history, both for repairs and oil changes. This will help you gauge how well the car has been maintained by looking at things like the condition of belts and hoses, as well as any fluid leaks or damage to parts.