How to diagnose a used car in 3 minutes when buying, so that later it won’t be excruciatingly painful

Homemade cars 30 689 7

To avoid buying a used car with a damaged engine, you need to be able to check it. You can determine that the engine has exhausted its resource in several ways in literally 2-3 minutes.

Checking crankcase pressure using the cover

If you unscrew the oil filler cap while the engine is running and place it on top, it should not be pushed out. If it rises, then this indicates a breakthrough of gases from the combustion chamber into the crankcase, which does not happen in a working engine. When the cap lies quietly, or is even slightly sucked in, this means that everything is in order with the piston.

How to diagnose a used car in 3 minutes when buying it so that it won’t be excruciatingly painful later

Oil vapor check

After turning off the warm engine, you also need to open the oil filler cap and see what fumes come out of it. In a normal engine, a white oil mist rises from there without a burnt smell. Blue smoke with a burnt oil smell indicates wear.

In addition, you can look at the back of the lid. It should be in clean oil, not in carbon deposits.

Checking the dipstick

Be sure to pull out the dipstick and check the oil level.

You need to examine its color. It should be clear or amber, but not black. You can also rub a drop of oil between your fingers. The oil film must retain its sliding properties for a long time. Bad oil will become rough after just a few rubbings. If it is in this condition, then it is better not to buy the car.

Checking soot in the exhaust system

If you insert a finger, maybe wrapped in a handkerchief, into the outlet of the muffler and wipe the wall of the tube, it should remain almost clean. The presence of moisture due to the formation of condensation is normal, the main thing is that there is no soot in the form of loose carbon deposits and oil.

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Comments (7)

#1 Max Guests October 27, 2020 00:42
5

Nonsense, you’re not looking at a new car, even a one-year-old car will have soot or oil on the exhaust pipe, black oil indicates that it’s time to change it, just like a broken engine. If you take into account everything that is listed, then a new car at a car dealership will fit these parameters.
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#2 Sergey Guests October 27, 2020 02:00
4

If the engine oil remains as clean as when you fill it, this means only one thing: the oil you are pouring is not suitable for your engine. Oil simply doesn't clean your engine. all dirt and carbon deposits that necessarily form during engine operation must be washed out with oil and settled in the oil filter. The oil will gradually turn black. If this does not happen, then the oil does not wash!!! The oil can remain clean only on a canola engine, and only for the first 2-3 thousand mileage
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#3 Azat Makhmudovich Guests 29 October 2020 09:28
1

The only thing you can pay attention to is the crankcase gas pressure. If smoke comes out of the breather, then the piston valve needs to be looked at.
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1. #4 Yura Razborkin Guests 31 December 2020 19:54
  1
  
  And this is also nonsense. And it doesn’t apply to diesel engines at all. Since the vacuum pump pumps air into the crankcase)))
  
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#5 Almukhametov Rafik Guests 10 December 2020 16:05
3

GM oils tend to darken quickly, and when choosing Opel, Chevrolet, etc. cars that are part of the GM corporation, this should be taken into account, especially since Ecotec engines are high-speed.
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#6 Yura Razborkin Guests 31 December 2020 19:58
1

What nonsense and nonsense from the teapot, this article))). All you really need to pay attention to is that the butter is not the color of coffee with milk (water emulsion), and everything else described by the author of this stupid article is complete nonsense. Including the pressure of crankcase gases, especially for a diesel engine in which the vacuum pump pumps into the crankcase.
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#7 Sergey. Guests 3 January 2021 21:40
0

When purchasing usedauto, there will definitely be deficiencies in the engine's operation. But even from the photo you can determine that the engine needs to be overhauled - pay attention to the instrument panel. The engine is warmed up to operating speeds of more than 50 degrees, the odometer needle is 0., idle speed is about 800. On this engine After the purchase, you will still drive. Diagnostics will show you exactly. My advice for inexperienced drivers.
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