What to look for when buying a used car?

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Buying a used car can be a nerve-racking experience. Especially the drive home, hoping nothing will break. Before buying any used car, you must know a few things to check, just to be sure you’re not purchasing trash. Often car owners sell their cars when it’s time to invest big money and it’s not worth it. It’s crucial to take your time and check the car properly. I will go through a few things to keep in mind when purchasing a used car.

Buying a car under 100.000 miles should not have any major issues, but if the car was not driven properly, things can still go wrong.


The engine is the most crucial part to check if is working properly. When checking an engine, you have to bear in mind if it’s diesel or petrol.


If you are after a diesel, the first thing to check when starting the engine is smoke. In general, a little black smoke coming from the exhaust is normal but too much black smoke can indicate carbon deposits from incomplete combustion. Also, black smoke can be caused by over-fuelling, indicating too much injectors wear. Bear that in mind!

Blue smoke is a huge NO! Because blue smoke indicates oil burning. This could be from a bad turbo seal, sensors or the worst Worn Piston Rings, Worn Cylinders, Worn Guides etc. The list goes on and the problem is quite hard to diagnose. Stay away and don’t buy a car that emits blue smoke.

White smoke in diesel is usually a symptom of bad injectors, timing gear, low cylinder compression and fuel pump. Again, stay away! Do not confuse white smoke with condensation from the exhaust.


A petrol engine is much cleaner than diesel, therefore, black smoke is an indication that the engine is running rich. Meaning that the air and fuel mixture are not adjusted correctly.

Blue smoke has the same causes in a petrol as diesel. Burning oil

White smoke can be caused by a coolant leak in a patrol car. Worn piston valves, bad fuel injectors and similar causes as in the Diesel engine.

Petrol and Diesel

For both fuel type engines, you should check the quality of the oil. Of course, in a diesel car, the colour would be darker but for both, you should inspect there is no brown bubbles or crusty brown residue. Also, inspect the dipstick for a milky residue. All of this will indicate a coolant leak, potentially a head gasket issue.

Overall to inspect the health of the engine (injectors, turbo etc) I advise paying a mechanic or investing in a quality ECU Software Tester.

Also, check under the car for any leaks from the braking system, radiator pipes, transmission oil and engine oil leaks.

The timing belt should be checked, if the seller claims it was replaced, ask for proof. Some vehicles have a timing chain instead. Both are under the engine cover and cannot be seen. Usually, a timing belt needs to be replaced between 60.000 and 100.000 miles. If there is no proof of service, you should consider replacing the timing belt after the purchase. As for the timing chain, it is changed at a much greater interval.

Test Drive

Never buy a car from a private seller without going on a test drive. When test driving the car, make sure you drive until the vehicle gets to operating temperature. This will unveil any problems that are hidden by cold parts.


As you test drive the car pay attention to the clutch biting point and accelerate the car a bit more aggressively than usual to notice any clutch slipping.

I also own a van, and the clutch only slips after 10 to 15 minutes of traffic driving. If the car is fitted with a flywheel, pay attention to any knocking sounds to indicate a worn flywheel.

Automatic Transmission

While checking if the clutch is working properly, the transmission should get a look over too.

The first thing to do is to shift gears while stationary. This will allow you to look for any harsh shifting. If you hear a grinding noise while shifting, then there is something wrong with the transmission

You need to pay attention to the delay time between shifting gears.


Well, if the take takes a few seconds to shift from Natural to Drive or Reverse to Drive, then there is a problem with the transmission.

Lastly, check for slippage, while driving accelerates the car aggressively and watch the RPMS, if they go up and the car is not moving at the rate it should, you have a slippage problem.

Manual Transmission

In a manual car, the clutch should be your main focus. You should also, press the clutch pedal and select all the gears while stationary or while driving to ensure a smooth gear change.

Pay attention to any burned clutch smell when the vehicle is at operating temperature. I remember when my father brought a 4×4 when I was younger. We brought the car, and 20 miles down the road the clutch started smelling and slipping. It was an easy temporary fix, by adjusting the cable. But don’t make the same mistake. Check the clutch when the car is warm!


I advise checking any car’s history by its VIN number or number plate. There are plenty of companies online but, their data are not always accurate. If the car was involved in an accident and it was not declared. The details will not show on any database.

The first thing to inspect it’s the car’s frame, open the bonnet, look at the bonnet bolts and hinges, you might be able to see the frame of the car on both sides of the engine. Also, look under the car for any new parts, such as rods and control arms.

When inspecting the paint, open the doors, bonnet, hood and look for any tape line or overspray.  Also, check if all the panels are aligned correctly.

The best way to check the paint is to invest in a Paint Meter. This will tell you the thickness of the paint around the car. If the readings are slightly off on one panel of the car. You should know it has been repainted.

“Take care of your car in the garage, and the car will take care of you on the road.”

Amit Kalantri

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