MDEP Highlights

January 9, 2009 

Before

After

This weeks MDEP Highlights demonstrate how important it is to diagnose diesel combustion problems early. The MDEP engine baseline evaluation result indicates that the engine fuel injectors are not atomizing the diesel fuel correctly.  The diesel fuel that is injected is hitting the cylinder walls and causing a dilution of the wall and ring lubrication.  This is seen by above normal Carbon Monoxide and Hydrocarbon readings. This phenomena is known as “cylinder wall wash down” which leads to an increase in friction and which can cause broken piston rings and scored cylinder walls.

By evaluating the five gas and DPM results for the 1994 Cat 3306 engine with over 13,000 hours, it is possible to diagnose that the engine needs fuel injectors replaced. The engine during acceleration will be emitting white smoke as seen in the five-gas which has an above normal Hydrocarbon reading. The engine Carbon Monoxide reading is above normal which can be seen by the human eye during acceleration as blue smoke. The blue smoke is due to the engine cylinder wall lubrication burning with the oil diluted diesel fuel which is due to the bad injectors.

Once the engine fuel injectors were replaced, the Hydrocarbon readings returned to normal. However, the Carbon Monoxide readings remained above normal. This is an indication that the engine fuel injector problem most likely caused permanent ring and cylinder wall damage. If in fact that is the case, the engine is significantly closer to an expensive engine overhaul. During the next evaluation, the five gas Carbon Monoxide readings will determine if the engine does in fact have premature engine damage which is due to the fuel injector problem or if the problem was caught in time.

Let’s look at the above problem in laymen’s terms.  A person who experiences a cancer diagnoses asks the question, “Will I live?”   In almost every cancer case, the doctor will explain that the earlier that cancer is diagnosed the better the chance you have. However, if you don’t find the cancer in time, the doctor will tell you what no one wants to hear “Get your affairs in order”. This is the same as saying “If you find the engine problems early, you won’t have to replace the dead engine!” 

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