DDAMAGE AND FAULT CAUSES IN A TURBOCHARGER
Understanding why a turbocharger has been damaged before replacing it.
A damaged turbocharger is not always the initial cause of the failure. It may be the result dof a problem originating in the engine, the lubrication system, the air intake d, the exhaust or the turbocharging system.
Replacing the turbocharger without identifying the cause of its damage may lead to a further breakdown, sometimes very soon after fitting.
It is essential to investigate the cause of the previous failure and to check the oil d, air dand exhaust dsystems, as well as the engine’s peripheral components.
1 — Damage caused by a foreign object
A foreign object entering the compressor side or the turbine side may strike the turbocharger’s impellers at very high speed.
The vanes may then become scored, bent or broken. The resulting imbalance can then very rapidly cause damage to the shaft and the bearing system.
Possible causes
- debris present in the intake circuit d;
- a damaged or incorrectly fitted air filter;
- a fragment from d’a hose or d’a component of the d’air system;
- ddebris from the engine or the turbine-side exhaust manifold;
- system not sufficiently cleaned following a previous fault.
To be checked before replacement
Carefully inspect the air filter, the intake ducts d, the hoses, the intercooler, the intake manifold dand the exhaust system d. No debris must remain in the system before fitting the new turbocharger.
A turbocharger whose turbine blades have been damaged by a foreign object must not continue to operate.
2 — Contaminated or dirty oil
Engine oil lubricates the turbocharger’s bearing system. The presence of particles, deposits or contaminants in the oil can cause scoring, accelerated wear of the bearings and damage to the shaft.
Possible causes
- heavily worn or contaminated oil;
- oil change intervals that are too long;
- a clogged, faulty or unsuitable oil filter;
- metal particles resulting from wear or dengine failure;
- residue remaining in the system following an engine repair;
- oil contaminated by fuel or coolant.
To be checked before replacement
The oil and filter must be replaced when required by the installation procedure. The lubrication system must be checked and kept perfectly clean. Following engine failure or the presence of metal filings, a thorough cleaning of the system is essential.
3 — Insufficient lubrication or a fault din the oil dsupply
The turbocharger rotates at very high speed and is directly dependent don a correct oil supply. Even a brief interruption in lubrication can rapidly damage the bearing system and the shaft.
Typical signs may include significant wear on the bearing surfaces, scuff marks, material transfer or discolouration caused by excessive temperature.
Possible causes
- d’ oil supply line blocked or damaged;
- d’ oil pressure is insufficient;
- clogged or unsuitable oil filter;
- a seal or assembly restricting oil flow;
- failure to pre-lubricate the turbocharger before the first start-up;
- degraded oil or oil unsuitable for the engine’s specifications;
- dly low oil level;
- contamination or dilution of the oil.
The new turbocharger must be lubricated in accordance with the installation procedure. It is also essential to ensure that oil is flowing correctly to the turbocharger before running the engine.
4 — Overheating and excessive temperatures
Excessive temperatures can degrade the oil, promote the formation of deposits and affect the internal components of the turbocharger.
An abnormally high temperature on the exhaust side may also result dfrom an engine fault, which must be identified before replacing the turbocharger.
Possible causes
- dexcessive exhaust gas temperature;
- dinjection or combustion problem;
- incorrect engine settings;
- the engine operating outside its specified parameters;
- severely degraded oil;
- turbocharger lubrication problem.
To be checked
d’ injection system, the intake, the exhaust, the lubrication system and the engine’s operating parameters must be checked to identify the cause of the excessive temperature.
5 — Turbocharger overspeed
Over-speed occurs when the turbocharger is forced to operate beyond its normal operating conditions.
The stresses placed on the compressor wheel, turbine wheel, shaft and bearings then increase significantly. Significant or repeated overspeed can cause accelerated wear, deformation or failure of the rotating components.
Possible causes
- a leak in the boost system;
- a punctured, cracked or incorrectly connected hose;
- a leaking intercooler;
- pressure control or variable geometry system operating incorrectly;
- significant restriction in the intake d;
- inappropriate engine settings or mapping;
- a power increase causing the turbo to operate beyond its specified limits.
To be checked before replacement
Check for leaks in the turbocharging system and inspect the hoses, the intercooler, the intake, the turbo control system and the boost pressure settings. If the vehicle has been remapped, its settings must also be taken into account during diagnosis.
A failed turbocharger may be the result dof another problem
When a turbocharger is damaged, simply replacing the part without investigating the underlying cause may lead to the new turbocharger failing.
Before any replacement, it is therefore important to check the engine and its associated systems, in particular the lubrication, air dintake, the boost system, the exhaust and the dinjection system.
Before ordering a new part, identify the fault and check the part number of the turbocharger fitted to your vehicle.
NEED SOME HEL D?
Check our troubleshooting guide or contact ALFI TURBO for to identify your turbocharger.
IDENTIFYING A TURBO FAULT CONTACT ALFI TURBO