Original diagnosis problems-Engine or part replacement

ENGINE OR COMPONENT REPLACEMENT…Original Diagnosis Problems

The installer’s nightmare….repeat failures. You have changed an engine, cylinder head, or crankshaft only to have the replacement fail for the same problem, or another problem, only a short time later.

vacuum guage
vacuum guage
leak down tester
leak down tester
timing light
timing light

The Solution…proper original diagnosis.

There are many situations that occur in today’s vehicles that cannot be fixed by the replacement of an engine, head, or crank. Damage to these parts is only the result, not the cause of the problem. One example of a sensor/system failure is a blown head gasket or failed piston. The engine, piston, or head is changed. Shortly the customer returns with a blown head gasket, or part of the piston burned away. During the original replacement, before the vehicle was released to the customer, the original problem was not found and corrected.

Before replacing any of these components, you must first find the real problem that caused the failure. The purpose of this Engine Portal Tech Talk is to inform you, in the strongest possible way, of the consequences of not diagnosing and checking the systems that make an engine operate.

Computer diagnosis
Computer diagnosis

It is important to remember that today’s vehicle is completely controlled by computers and sensors. There may be as many as 20 sensors feeding information to the vehicle “master control unit “ (MCU) or brain box. There are other sensors, while not directly attached to the MCU, that do affect the information the sensors feed to computers.

These sensors are part of systems that operate the vehicle properly. All of the systems must be in proper operating order for the engine to function properly and have normal combustion. Abnormal combustion will result in detonation.

Examples of systems that play an important role in the proper running of today’s engine are the exhaust system, cooling system, oiling system, fuel ignition system, EGR system, air temperature system, A.I.R. (thermactor) system, or RCV-CCV system.

 These systems are all controlled by the sensors that send signals to the MCU. The result of this information is a properly or improperly operating vehicle. Failure of any of the sensors which supply information on these systems, or failure of the system itself, can cause a major engine failure.

Just as with the original engine, under proper care and maintenance, it is reasonable to expect mileage from remanufactured engine of 100,000 miles and up if all conditions are the same. The difference then is in the changing over of an engine or part.

The sensors/systems that provide information to allow the engine to run properly also have 100,000 miles on them. They must be carefully checked before, and after, the engine or component is replaced.

We, as a remanufacturer, have little control over the conditions under which the engine or component is replaced. We are beginning to see more and more detonation, scoring, and premature failure problems that can be directly traced to failure on the part of the installer to properly diagnose the reason for the original failure, or faulty reinstallations relative to sensors and systems that control the engine.

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About Danny Bender 88 Articles
The premier engine troubleshooting resource site. DannysEnginePortal.com offers information on engine rebuilding, engine repair, machine operations, engine testing, and possible solutions.

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