Damage Caused to the Turbocharger
Most Common Damages Occurring on Faulty Turbochargers
While, from what is known about the early days of the turbo era, hot shut-off and lack of oil were considered the main causes of a turbocharger’s lifespan, today it is over-revving and failure of the VTG unit that trigger these issues.
Due to chip tuning or sealing defects in areas carrying boost pressure, the turbocharger’s speed increases disproportionately. After a whistling noise that lasts for a more or less extended period, most turbochargers fail with a rattling sound due to worn bearings or even a broken shaft.
The information provided here helps to identify the damage and is an excerpt from our practical training course "Analysis of Turbocharger Damage," which is offered at regular intervals for those interested in perfecting their expertise.
Damage Caused by Shock
Damage caused by shock and the penetration of foreign objects into the turbine housing or compressor housing is clearly visible on the compressor wheel and turbine wheel. When installing a new turbocharger, the air intake duct and exhaust manifold must be checked for the presence of foreign objects. Attention! Turbochargers with such damage must never be used.
Contaminated Oil
Contaminated oil causes damage to the turbocharger in the form of scoring on the bearing surfaces. Where does the contaminated oil come from?
- Friction caused by engine wear
- Poor-quality oil
- Poor quality or clogging of the oil filter
- Often after engine repair due to insufficiently cleaned oil channels within the engine
Oil Supply Incident
A repeated oil shortage lasting a few seconds results in significant wear traces on the bearing surfaces, a bluish coloration, and/or discoloration of the bearing on the shaft, leaving a yellow mark.
- Turbocharger installation without pre-filling the lubrication system
- Insufficient oil and filter replacement/intervals that are too long
- Oil dilution by fuel/glycol
- Prolonged downtime
- Operation in excessive inclined positions
- Loss of damping properties of the lubricant due to over-revving of the rotor shaft caused by chip tuning or sealing defects
Overheating
Failures caused by excessive exhaust gas temperatures or frequent engine disconnection without sufficient cooling time result in carbon deposits on the turbocharger and the oil supply line. The turbine side bearing and piston ring seal are particularly affected in this case. Possible causes of these damages include:
- Clogging/shrinking of the air intake filter
- Hot disconnection of the engine
- Poor-quality oil
- Incorrect engine tuning
Damage Caused by Over-Revving
Failures due to excessive turbocharger speed on tuned vehicles or in the case of non-sealed pressure hoses between the turbocharger and the intake pipe. Elevated speeds lead to the formation of an extremely high vacuum upstream of the compressor wheel, causing the starting disk and axial bearing to wear quickly. When critical speed ranges are reached, the rotor shaft, excited by residual imbalances, tends to break.