The damage most frequently occurring on faulty turbochargers
While, according to what we know about the beginnings of the turbo period, hot shutdown and lack of oil were considered to be the main cause of the end of life of a turbocharger, today it is Today the overspeed and the failure of the VTG unit which are the triggers.
Due to chiptuning or leaks in areas carrying the boost pressure, the turbocharger rpm increases disproportionately. After a more or less long hissing noise, most turbochargers give up the ghost with a knocking noise due to worn bearings or even a broken shaft.
The information mentioned here serves to determine the damage and is year excerpt from our practice-oriented course "Damage analysis on turbochargers" for expert training, which we offer to interested persons at regular intervals.
Impact damage caused by foreign objects entering the turbine housing or compressor housing is clearly visible on the compressor wheel and turbine wheel. When installing a new turbocharger, the air intake channel and the exhaust manifold must be checked for the presence of foreign objects. Warning ! Turbochargers with such damage should not continue to be used under any circumstances.
Dirty oil causes damage to the turbocharger in the form of streaking on the bearing surfaces. Where does dirty oil come from?
Friction due to engine wear
Lower quality oil
Poor quality or clogged oil filter
Often after year engine repair due to insufficiently cleaned oil channels in the engine
Oil inlet incident
A repeated lack of oil and lasting a few seconds leads to significant traces of wear on the bearing surfaces, a bluish coloring and / or discoloration of the bearing on the shaft, yellow trace.
Installing the turbocharger without pre-filling the lubricant system
Insufficient oil and filter replacement/too long intervals
Oil Dilution by Fuel/Glycol
Excessive Reclined Operation
Loss of the damping properties of the lubricant due to overspeeding of the rotor shaft due to chiptuning or leaks
Failures due to excessive exhaust gas temperatures or frequent engine disconnection without a sufficient cooling phase lead to carbon deposits on the turbocharger and oil delivery line. The turbine side bearing and the piston ring seal are particularly taken into account in this case. The possible causes of this damage are:
Clogged/restricted air intake filter
Motor Hot Disconnect
Lower quality oil
Improper engine tuning
Damage caused by over-revving
Failures due to excessive turbocharger rpm on pushed vehicles or in the case of leaking pressure hoses between the turbocharger and the intake pipe. The high rpm causes year extremely high vacuum to form upstream of the compressor wheel, so that the starting disc and the axial bearing wear out quickly. When reaching over-critical speed ranges, the rotor shaft, excited by residual imbalances, tends to break.