The Most Common Causes of Oil Leaks from Turbocharger

Oil leaks from the turbocharger are among the most common problems. However, an oil leak does not always indicate a turbocharger failure.

There are several causes related to other elements of the engine unit, such as a clogged oil return line, a reduction in the diameter of the oil return due to an improperly fitted gasket (using silicone instead of/along with a gasket), excessive oil level in the engine preventing free flow to the sump (especially common in engines equipped with a diesel particulate filter), or overpressure in the engine crankcase, which can be caused by poor engine condition, resulting in blow-by gases.

Leaks That Qualify the Turbo for Repair

Oil leaks caused by factors outside the turbocharger, meaning they do not result directly from a turbocharger failure, do not require turbocharger repair, provided that the causes are eliminated. For example, when oil enters the compressor wheel along with the intake air, simply replacing the crankcase breather is enough without the need for turbocharger intervention. However, it is important to note that prolonged oil leaks from the breather can eventually damage the turbocharger. Oil sticks to the compressor wheel blades, gradually causing imbalance.

On the other hand, if mechanical damage to the rotating system components or increased shaft play is found, oil leaks qualify the turbocharger for repair or replacement.

The Impact of Engine Oil Deficiency on Turbocharger Component Wear

To understand the nature of the problem, it’s important to recognize how precise a turbocharger’s construction is. The bearing system is designed so that the bushings are positioned between the stationary turbocharger core housing and the rapidly rotating turbine shaft. The design prevents any contact between cooperating elements throughout the turbocharger's operating range. In addition to lubrication and cooling, the oil film also ensures the stability of the shaft and turbine wheel operation while maintaining critical clearance tolerances of a few microns.

Modern turbochargers reach rotational speeds of up to 300,000 RPM. It is easy to imagine the consequences of insufficient oil. Within a short time, elements burn out and wear down (often the bearings wear into the shaft surface), leading to excessive play in the rotating system.

Examples of Failure Causes:

• low engine oil level (insufficient turbocharger lubrication and cooling)

• low-quality oil that is not resistant to high temperatures

• blockage, often due to carbon build-up, of the oil supply line and internal oil channels in the turbocharger (blocking oil flow)

• abrupt engine shutdown

• low oil pump efficiency

• worn, clogged, or low-quality oil filter

• oil dilution with fuel due to frequent diesel particulate filter regeneration (short-distance driving)

• extended intervals between maintenance

• oil dilution with water due to leaks from the head gasket

Adhering to Certain Key Principles Can Prevent Turbocharger Damage:

• use high-quality engine oil and oil filters, following the vehicle manufacturer’s recommendations

• follow recommended maintenance intervals

• replace both the oil supply and return lines with new ones

• always use new oil seals

• the engine should be cooled down after high-speed driving and warmed up before reaching high speed

• avoid driving only short distances

Most turbocharger failures are related to oil system problems.

A properly maintained turbocharger should operate faultlessly as long as the engine does, which is why following the principles of proper turbocharged engine maintenance is crucial.