Why Did the Diesel Engine Fail?

Sometimes people overhaul a diesel engine, and they just change parts without addressing the reason for the failure. This creates a real problem for the fleet or owner-operator because if those underlying issues are not resolved, the truck or equipment will soon be back in the shop needing another overhaul. 

The Cause of Engine Failure 

To successfully overhaul a diesel engine, you must not only replace the damaged parts, but you must address every system of the engine and diagnose what caused the failure. 

There are five main systems that need to be inspected thoroughly: 

  • Cooling System 
  • Lubrication System 
  • Valvetrain System 
  • Combustion System 
  • Air Intake System 

Replacing the damaged parts inside the diesel engine without addressing the cause of the engine failure will lead to another engine failure, so make sure that every system is thoroughly checked before putting the truck or equipment back into service.  

WATCH: Why Did the Diesel Engine Fail?

Asking the Right Questions 

The very first question that needs to be asked is why is the engine being rebuilt? If the engine has a lot of miles or hours on it and it simply is time to rebuild the engine as a proactive measure that is one thing, but if the engine has experienced a premature failure that is a totally different scenario.  

If there was a failure, what components are being replaced along with the engine rebuild? This is very important because the answer can directly affect the warranty on the engine rebuild. Addressing the engine while failing to identify the cause of failure can be catastrophic. 

The Systems are the Solution 

The nature of the engine failure will point you in the correct direction.  

For example, if the engine overheated, the first system to look at would be the cooling system. Perhaps the water pump failed, and the thermostats are needing to be replaced. Failure to address these issues can lead to the rebuilt engine overheating again.  

If the engine experienced bearing failure, the oil pump, connecting rods, and oil cooler should be inspected. All of these could be contaminated with metal pieces that will damage the rebuilt engine and cause premature failure once again.  

Hiding in Plain Sight 

Another issue that you must be very careful about is symptoms that mask the causes of failure.  

For example, it may appear that the engine has excessive oil consumption which will naturally cause you to look at the valve seals, piston rings or liners. If the engine has many miles on it these components will no doubt show signs of wear and be required to be replaced.  

But is that the actual cause of the engine failure?   

The turbocharger can be the cause and will look like excessive oil consumption. Replacing the turbocharger along with any other parts in the engine that need to be changed will result in a successful repair. 

But wait, there’s more.  

The air compressor can suck oil up into the cylinder head and look like excessive oil consumption as well. So is the cause of the oil consumption the valve seals, piston rings or liners, the turbocharger, or the air compressor?  

Therefore, it is so important to ask the correct questions when the truck or equipment comes in with various symptoms of engine failure. In our next article we are going to focus on the steps required to successfully overhaul a diesel engine. If you'd like to learn more about the engine parts manufactured by AFA Industries, or if you would like assistance in diagnosing why a diesel engine has failed.

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