How to check the engine condition

A few more bits of information

As I can see from the statistics, this page among with the page on automatic transmission is most popular. Here I described few tips that may help you to check the engine condition when you're buying a used car. Though, evidently, you can ask a mechanic to check it for you.

At the beginning

I suggest you to avoid quite new cars (two-three years old) that already have the engine rebuilt. Normally, an average engine should run at least 150,000 miles (240,000km) without any major repair. If it needs serious repair after 40,000 miles, (65,000km) think about quality such engine was built at the plant.
If you find any engine defect (I describe below how to do it), for example an oil leak or some strong noise, don't let the salesperson to mislead you. He may tell you the leak is "overflow from the recent oil change" or "the noise will disappear later after break in period". Generally defects never disappear by itself.

Look at the internal parts through the oil filler hole (Don't open the oil cap while the engine is running!)

Check the oil pressure

Try to check oil pressure on a cold engine (at least an hour after the engine has been turned off). Start the engine, and look at the low oil pressure warning lamp or oil pressure gauge on the instrument panel. The time between the engine start and the time you note oil pressure at the instrument panel should be no more than 1 - 2 seconds.
! If this time is longer than 2 seconds, it means that either the oil filter is bad or the engine is too worn.
! If the low oil pressure warning light goes on while engine is running or idle, or the engine oil pressure gauge indicates too low oil pressure, it also means that the engine is too worn or has some defect.

Check the oil level and look for leaks

If you have no clue on cars, here is detailed explanation If you find the oil level at "min" or less on the dipstick, then probably this engine burns more oil then permissible.
! If the engine oil on the dipstick is white (or the coffee with milk color), it most likely means a presence of engine coolant in the oil, which is evidence of an internal engine defect (like blown head gasket). Such defect is common for some V6 and V8 engines. Check the engine thoroughly for oil leaks. The more leaks, the worse the engine. Good engine should be dry.

If you find evidence of badly made repairs, avoid any such car.

Check breathing pipe

Check the cooling system (but never open the radiator or overflow tank cap while the engine is hot!)

To begin with, check the coolant level in the overflow tank. It should be between the "min" and "max" points, as in this picture. The coolant should not have even a spot of engine oil. It should be clean and transparent, it also may be of green, red, blue or yellow color (depending on the maker). ! If you find engine oil inside the radiator or expansion tank, it's bad. It may be evidence of an internal engine defect (a blown head gasket, for example). Check the radiator and water hoses for leaks. Check the water pump also. It should not have coolant seepage. The radiator should not have any traces of damage.

Check the end of the exhaust pipe (only with the engine turned off!)

! If you find dry, black buildup inside the exhaust pipe, it means this car expends more fuel than it should (note, diesel engines usually have more black buildup inside the exhaust pipe). ! If the buildup is oily, this car consumes too much oil. You'd better avoid it. In good condition, the engine's exhaust pipe should be dry. It may have thin red-brown or gray buildup inside. Look at the image. This is acceptable.

Check the smoke

Start the engine. Let it idle for 3-5 min. Then ask the car owner to press half way down on the accelerator (to 4500-5000 engine rpm) for 2-3 sec. and check the smoke from the exhaust pipe.
! If there is blue or grey smoke, the engine consumes more oil than is permissible. Avoid such a car. Black smoke means the engine expends too much fuel (A little black cloud at the moment of acceleration is permissible for petrol engines, and a little more for diesels).
! White smoke with a smell of burned oil means very intensive oil consumption.
! If you see steam after the engine has achieved normal operating temperature, it means there is some cooling system defect - blown head gasket, for instance. (Note, if the engine is cold or has just started, steam or water coming from the exhaust pipe is O.K.)

How to check air conditioner Switch the air conditioner on. If it's working, its compressor (the disk indicated with the arrow on the image) should begin to whirl. Sitting inside the car switch the air conditioner on. Note, the air, blowing out from ventilation outlets should get very cold (not just cool) in few seconds. There should be no strong noises when switch the air conditioner on.

Listen for noises when the engine is running

There shouldn't be any strong noises, knocking or whistling during acceleration or idling. (However Diesel engines are more noisy)

Look at the instrument panel

All the warning lights for low oil pressure, check engine, low oil level, overheating, etc, should go off after the engine is started.
I receive lot of questions about "check engine"or "service engine soon" light. If it goes on while driving it means electronic system of your engine has some defect. Usually it refers to emission control system. For example some sensor could be disconnected. The mechanic can find the exact reason by scanning the fault codes from the vehicle computer with special diagnostic equipment.

Check the engine performance

While test driving try to accelerate the car, there should be no delays, no hesitation if the engine is fully warmed up. The idle should be stable during a stop.

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