Turbocharger Failure Fact Sheet

2.0 Contaminated Oil Supply

A turbocharger that receives lubricating oil from an engine oil supply that is contaminated with abrasive material will experience accelerated wear of bearing surfaces that will eventually lead to rotating assembly contact with the housings and ultimately turbocharger failure. Sources of lubricating oil contamination include engine bearing material from failed engine bearings, dirt introduced into the engine during major engine maintenance or even blast material (i.e., glass beads and/or sand) that was introduced into the engine/ cylinder head assembly during the rebuild process that was not properly removed during the cleaning process. Many people rely on the engine oil filter to remove these contaminants after they are introduced in the system. However, the engine oil filter is designed to bypass the filter element under certain conditions (i.e., cold start or high RPM/high oil pressure conditions) to ensure that the engine receives lubrication. Under these conditions, unfiltered oil is circulated throughout the engine lubrication system including the turbocharger.

2.1 Turbocharger Damage from Contaminated Oil Supply

A turbocharger that has received lubricating oil contaminated with abrasive foreign material typically exhibits considerable grooving and wear of all bearings surfaces as shown in the figures below.

Another source of engine oil contamination is engine coolant (i.e., antifreeze) that will ultimately result in failure of the turbocharger and engine bearings. Lubricating oil that is contaminated with engine antifreeze produces considerable wear of turbocharger bearing surfaces and a distinct discoloration of the bronze bearing components as shown below.

2.2 Contaminated Lubrication System Considerations

Once contaminated, the engine lubricating system must be thoroughly cleaned to prevent future engine and/or turbocharger damage. A lubricating system component that is commonly overlooked is the chassis mounted engine oil cooler if the vehicle is so equipped. For example, if an engine rod bearing fails, the bearing material, or “babbet”, is circulated throughout the engine lubrication system and turbocharger. Often, the engine and turbocharger are rebuilt or replaced but the chassis mounted oil cooler is never serviced resulting in premature failure of the rebuilt/replacement turbocharger and damage to the engine bearings depending upon the severity of the contamination.