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Difficult start of the diesel engine

Here are some of the possible reasons of a problematic start of the diesel engine.
  1. The compression in the engine cylinders is low
  2. The plunger pairs of the fuel pump are worn down
  3. Thickening of diesel fuel at low temperature
  4. Pollution of the injector nozzles, malfunction of injectors, black exhaust smoke
  5. Malfunction of the starter or weak accumulator
  6. Malfunction of the glow plugs control system and breakdown of glow plugs
  7. Fuel filter pollution
Изображение проблематики


  1. In case of low compression warm start of the diesel engine is not very different from a cold start as in both cases it is rather difficult. Also the engine start is not harsh, explosive but rather backward. Low compression can also be explained by worn down cylinders, destruction of piston rings, sticking of the piston rings, gapping or failure of valves or piston top collapse.
    If there is sticking of the piston rings, it is recommended to use the Anticarbon product, which is an anti-carbon engine cleaner that penetrates into every cylinder through the glow plugs or openings of injection nozzles. It worth to be noted that before the change of motor oil it is highly recommended to use the Atomex TotalFlush product, an oil system cleaner. In case of slight wear of cylinders and piston rings it is recommended to carry out the full treatment of the engine oil system with the help of Revitalizant® for diesel engine or Atomic Metal Conditioner Maximum with 1 Stage Revitalizant® products.
  2. Another frequent reason of the difficult warm start of the diesel engine is wear of the plunger pairs of the fuel pump. In this case the cold fuel can be pumped with the plunger in high pressure fuel pumps but after the fuel warms up it becomes more fluid and cannot be pumped in the proper volume for the regular engine start.
    Slight wear of the plunger pairs of the high pressure fuel pump can be restored due to special cleaning agents and the following treatment of the diesel engine fuel system with Revitalizant for fuel equipment. Here you will find recommended fuel system cleaners for diesel engines:
    • VERYLUBE fuel system cleaner (Diesel)
    • Diesel-Lux - complex fuel treatment
    • Multi Cleaner (Diesel) – protection of diesel engine
    • F8 Complex Formula (Diesel) – protection of diesel engine
    Here are also recommended XADO gel revitalizing agents for renovation of worn plunger pairs of high pressure fuel pumps:
  3. The third reason of the difficult start of the diesel engine is thickening of diesel fuel at low temperatures. In this case it is recommended to add an Antigel, a superconcentrated diesel fuel treatment, which will help to decrease the temperature of the diesel fuel thickening by 7-12 °С. The product should be added regularly at the ambient temperature not higher than 5 °С.
  4. In case of severe pollution of injection nozzles it is recommended to conduct regular application of fuel system cleaners for diesel engine. If black exhaust smoke appears by engine operation, it indicates critical amount of contaminations in the diesel particulate filter (DPF). By malfunction, the injection nozzles should be checked and, if necessary, changed.
  5. If the starter fails to perform properly, it should be repaired. If there is a weak accumulator, it should be changed or replaced.
  6. In case of failure of the advance injection system, it should be checked and repaired by specialists.
  7. Failure of the glow plug control system and heating plugs may be eliminated with the help of functional check of the machinery or, if necessary, by their well-timed replacement.
  8. If there is clogging in the fuel filter, it should be replaced with the following cleaning of the fuel system with the help of the cleaning agents.