Ask Professor Diesel 04/28/2014 – Engine Noise


This week’s question comes from Ibrahim in Indonesia about engine noise

Dear Professor Diesel:

We installed your MD170 engines two years ago, and they have been working great. However, recently, they seem to be very noisy. Is this normal? Are there ways to correct the problem?


Engines can get noisier over time, especially with heavy use. The reasons why can come from a variety of sources:

  1. Vibration over time loosens bolts, fasteners, and belts
  2. Fuel and oil filters have not been changed according to the schedule listed in your manual, or you have been operating with dirty fuel
  3. The engines are using the wrong fuel
  4. Oil has not been changed
  5. The engine timing is off
  6. The injectors are dirty

With the limited information you provided, it sounds as if your engine is ready for overhaul. How long has it been since this was done? If the engine was recently overhauled and mechanical causes can be eliminated, a variety of noise reducing methods are available, such as:

  1. Insulating the exhaust.
  2. Adding silencers.
  3. Changing the exhaust configuration.


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