Repeat Engine Failures – Not Properly Diagnosing The Original Problem

Repeat Engine Failures - Not Properly Diagnosing The Original Problem
Repeat Engine Failures - Not Properly Diagnosing The Original Problem

The installer’s worst nightmare, repeat engine failures; from a lack of proper diagnosis.

So, you have replaced an engine, cylinder head, or crankshaft in your vehicle. But, a short time later; you have repeat engine failures, for the same problem.

Consequently, not finding the original problem, can cause repeat engine failures; costing a ton of money and inconvenience.

So, repeat engine failures, are nothing new. And, there are many problems that occur in today’s vehicles; that cannot be fixed by replacement alone. For instance, a failure of an engine, cylinder head, or crankshaft; is only the end result and not the cause, of the original problem. Computers and sensors control, almost all of today’s vehicles. So, any one of them failing, can actually cause, repeat engine failures.

Blown Head Gasket
Blown Head Gasket

So, the engine, piston, or cylinder head is replaced. But, shortly after, the customer returns with the same or a new problem. Because, finding and correcting the original problem, never did happen. And, quite often its a leaking or blown head gasket.

So, before replacing any of these components, you must first find the original problem, that caused the original failure.

Diagnostic Steps, To Avoid Repeat Engine Failures:


Verify the Problem

Before one minute is spent on diagnosis; be certain that a problem actually exists. Because, if the problem cannot be verified; the problem cannot be solved or tested; to verify that the repair was complete.


Perform a Thorough Visual Inspection and Basic Tests

The visual inspection is the most important aspect of diagnosis! Most experts agree, that most engine problems, can be found; simply by performing a visual inspection.


Retrieve the Diagnostic Trouble Codes

If a diagnostic trouble code (DTC) is present in the computer memory; it is pointed out by illuminating a malfunction indicator lamp (MIL); commonly labelled “check engine” or “service engine soon.”


Check for Technical Service Bulletins (TSBs)

Check for corrections in bulletins, that match the symptoms. NOTE: (DTCs must be known, before searching for service bulletins. Because, bulletins often include information on solving problems; that involve a stored diagnostic trouble code.) Therefore, causing, repeat engine failures.


Look at Scan Tool Data

The best way to look at scan data, is in a definite sequence; that can tell the most about the operation of the engine.


Narrow the Problem to a System or Cylinder

Consequently, narrowing the focus to a system or individual cylinder; is the hardest part of the entire diagnostic process.


Repair the Problem and Determine the Root Cause

The repair or part replacement, must be performed; by following vehicle manufacturer’s recommendations. Also, follow manufacturers’ recommended repair procedures and methods.


Verify the Repair and Clear Any Stored DTCs

So, the purpose of this post, is to inform you in the strongest possible way; of the consequences of not diagnosing and checking the systems; that make an engine operate properly.

Another common mistake in diagnostics is; falsely condemning a part, that is really just out of adjustment. Consequently, adding to, repeat engine failures.

So, computers and sensors control today’s vehicles. Consequently, there may be as many as, 20 sensors; feeding information to the vehicle computer.

Computers and sensors control today's vehicles
Computers and sensors control today’s vehicles

And, there are also other sensors; while not directly attached to the computer; that do affect the information, the sensors feed to the computer. Furthermore, these sensors are part of other systems, that allow the vehicle to operate properly. So, all of these systems, must be in proper operating order; for the engine to function properly and have normal combustion. As a result, you risk, repeat engine failures.

Systems That Play An Important Role, In The Proper Running Of Today’s Engines Are:

Sensors send signals to the (MCU)
Sensors send signals to the (MCU)

These systems are all controlled, by the sensors that send signals to the computer. So, the result of this information is, a properly or improperly operating engine. Consequently, failure of any of the sensors, which supply information to these systems; or failure of the system itself, can cause major engine failure.

So, just as with the original engine, under proper care and maintenance; it is reasonable to expect mileage from remanufactured engines 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.


So, the sensors/systems that provide information; to allow the engine to run properly, also have 100,000 miles on them.

Therefore, if you have not found the original problem, keep looking. Otherwise, you could end up with the installer’s nightmare….repeat engine failures.

Thank You !