To carry out the initial diagnosis of the engine of a car that you like to buy, you do not need to have experience in the field of car mechanics or use sophisticated equipment. It is enough to know a few tricks, the use of which will save you trouble and, more importantly, big expenses later on.
One of the main things is to pay attention to the sounds made by the motor. The ideal time for this “listening” is when it is cold, because then some of the defects are much easier to detect. After starting a cold engine
there should be no noticeable knocking
of the hydraulic lifters, the replacement of which is complicated and expensive. If the impact of the pistons is heard well, this may mean severe wear of the parts and increased gaps between them.
If a rattling sound is heard from the gear chain, this is a signal of a damaged tensioner. A perfectly healthy engine should run quietly, steadily and evenly from cold, and the noise should gradually decrease as it warms up.
It is important to listen as well how the engine revs up after a sharp push on the gas pedal. Ideally, this happens quickly, without external noise and drops. If any sounds are heard during acceleration, it may even be due to knocking of the crankshaft bearings, which in turn means a serious engine defect.
Hissing air noise, may indicate a lack of tightness in the intake tract. It is important that all auxiliary drive components operate silently.
Often, used car sellers deliberately silence dangerous knocks in the engine with some simple malfunction, for example, loosening the fasteners of the exhaust system.
Apart from the sounds made by the bike, its condition can also be judged by its appearance. With the engine off, look through the hole in the valve cover into the cylinder head cavity. No black clots of oil should be visible. The lighter the color of the surfaces, the better. Well-maintained engines may have brownish surfaces, but without a thick layer of deposits. Sellers sometimes wipe the surfaces on top, so it’s best to use a flashlight and look at the details from an angle.
When checking the engine it is necessary
to check the oil plug
for the presence of black deposits on it. In winter, a whitish-yellowish emulsion may also form due to moisture condensation, but there should be no drops of antifreeze-like liquid (if antifreeze gets into the oil, it can lead to difficult and expensive engine repairs).
It should also be checked for oil leakage with the engine running and the filler neck open, as this could indicate a blow-by in the cylinder head. As a check, a cap or plug can be placed over the hole to see if it bounces around too much.
On the oil dipstick, its level should be closer to the upper mark, which indicates that the engine has been properly serviced. In doing so, the oil should not be too dark, although brand new oil may cause some concern as it may have been topped up to sell the car. If there is sediment on the dipstick, this could be a sign of a problem.
It is best
the engine should be covered with a thin layer of dry powder.
This indicates that there are no oil or antifreeze leaks. If working fluids tear, then noticeable traces are formed on the dust. Washed engines can, of course, hide traces of leaks. To make sure there aren’t any, you should use a mirror and a flashlight to check the back of the engine as well. Leaks around the cylinder head can be caused by increased crankcase pressure.
It is also important to check the cooling system for leaks. With a cold engine, look in the coolant (antifreeze) tank and make sure that engine oil does not get in there (if there is oil, it will float to the top in the antifreeze tank).
If the engine burns oil, then when starting cold from the exhaust
the first smoke will come out with a bluish tint.
To check for oil burn, warm up the engine and hold the engine at 3000 rpm. for ten seconds, then increase them sharply to 5000 rpm. If the engine is burning oil, a large ball of bluish smoke will come out of the exhaust. If, on the other hand, the oil consumption is high, then blue smoke will be seen at every sudden gas supply.
To determine if the engine is burning oil, one can also look at the end of the muffler. If there is a lot of black, velvety deposits there or it is greasy, this is not a good sign. Dealers, of course, know this and wiped the end of the exhaust pipe well. So it’s better to look inside with a flashlight.
These simple verification methods are well suited for initial evaluation. If after that you decide to buy the car, then it is recommended to carry out a more thorough diagnosis of the engine. It can include, for example, removing the spark plugs – their condition can tell a lot about the engine’s performance. Compression can then be checked and cylinder surfaces and valve seats inspected with an endoscope.
2023-05-02 07:03:54
#engine #bad #condition
