You will need
  • Level meter compression gauge pressure of the crankcase gases and other equipment for engine diagnostics.
You should first check how the engine starts in a cold condition. This is best done in the morning, so engine was cold. Serviceable diesel will start with a half-turn. If not start immediately - this is a bad sign (wear or piston rings). The cold will be significantly noisy, warm – much quieter. If you have a hot engine, on many models the heating of engage will not, and the start will occur due to the compression.
When you press on the gas pedal to warm the engine, check to see whether the smoke belching from the exhaust pipe. If the smoke is dark, so there is a wear oil ring problems or injector. White smoke means water in the fuel. Commonly used method: a white handkerchief or sheet of paper put under the exhaust. The presence of soot on the paper or fabric indicates increased consumption of oil or incomplete combustion. The turbo allowed the black smoke to power turbines, as well as when blipping. But it needs to be short and not thick. Should try the engine without the air filter. Maybe a clogged filter is the cause of increased opacity.
Irregular, tapping sound in engine performance indicates that the adjustment of the valves, and possibly, problems with the valves or piston. "Hard" sound in combination with the black smoke at high rpm means the early injection angle. Interruptions and grey smoke at idle in combination with shortages and black smoke at high – a late injection angle. A rough running diesel at idle in combination with the black smoke reveals the non-working injector. To test this, disable it. The engine will work gently.
Opening the oil cap, check no oil spray from the oil fill neck. Their presence is an indicator of blowby. The reasons for this can be many.
You should evaluate the General appearance of the engine compartment. If the nuts on the injectors and cylinder block are free of nicks, if traces of white or red sealant (black, from Japanese cars), so the engine has not been opened. You also need to check mounting bolts on all accessory devices. The condition of the ear is tested this way: to warm up the car, and immediately turn the ignition on. The oil pressure indicator should light up in 2-3 seconds. If before – liners should be changed.
At the station or in the garage equipped to measure compression. Compression should be at least 25. However, this value can be different for each engine size. The variation should not exceed 0.5 for a new car and 1-2 old. A large spread indicates a future overhaul. Low compression can be due to wear of the piston or worn valves. Wear of valve repair cheaper and easier.
The injector when the work needs to emit a characteristic sound and spraying the fuel in dusty condition. Spraying in the form of drops and jets is absolutely contraindicated the engine. With the injectors, you should evaluate the hoses for leaks fuel flow and reverse flow.
The color of the oil should be black, without impurities. Silver-grey shade of the color of oil indicates a recent use of molybdenum additives.
Cooling system
You should verify the absence of bubbles on a warm engine at medium and high rpm. Metal piping should be free of rust and red plaque (a sign that the engine was overheating).
The last step is the measurement of the pressure of crankcase gases. The high value of this indicator can only be due to worn piston or valves.