5 Ways to Kill a Turbocharger

Turbochargers are very reliable: less than 1% of turbos fail due to a manufacturing fault with the turbo itself. 95% of turbo failures are because of problems with oil starvation, oil contamination or foreign object damage.

BEFORE YOU FIT A NEW TURBO, FIND OUT WHAT CAUSED THE FIRST UNIT TO FAIL OR YOU RISK THE REPLACEMENT FAILING TOO.

1. Foreign Object Damage
Anytime a turbocharger ingests something — be it dirt, dust, a shop rag or a bolt left in the intake — it can spell disaster. Unfortunately, outside debris making its way across the blades of a compressor wheel (the intake side) accounts for 80 percent of all turbo failures. When this failure occurs, the leading edge of the compressor wheel’s blades will indicate any impact from the object(s), and the inducer bore (what the compressor wheel sits in) may show signs of contact or scarring.

The most common cause of debris infiltrating a turbo? A dirty air filter. That’s right, lack of maintenance on one of the most basic components on your vehicle can cost you a four-digit figure (turbo) and potentially a five-digit one if any shrapnel makes its way into the engine. Fortunately, being that most modern turbocharged applications utilize an intercooler (a heat exchanger positioned between the turbo and engine) to cool intake temps, it often becomes the catchall for compressor wheel fragments.

SOLUTION:
Run a quality air filter with an outerwear, keep it clean if it’s reusable or install a new one at the proper interval if it’s replaceable.

2. Overspeeding
Once a turbo is pushed out of its compressor map, it may not always produce more boost, but it will almost always create excess drive pressure, causing the shaft to see more speed than it was designed to handle. When overspeeding occurs, the turbine (exhaust) wheel is usually the first component to give way, and we’ve even seen a few come apart and exit the tailpipe at the speed of light. 

When overspeeding occurred, the thrust bearing checked out, which led to excessive shaft play followed by the compressor wheel making contact with the housing and effectively wedging itself sideways in the inducer bore.

SOLUTION:
Keep your turbo’s boost-to-drive pressure ratio as close to 1:1 as possible (1:1.5 is OK in most cases), which may entail running a wastegate to bleed off excess drive pressure or opening up the exhaust flow via a larger turbine housing.

3. Oiling Issues
Lack of proper lubrication (oil supply) will kill the bearings in a journal bearing turbocharger in short order. When subjected to a lack of oil supply for extended periods of time, the journal bearings will eventually begin to allow shaft play, followed by the compressor and/or turbine wheel making contact with its respective housing. Inadequate oil supply can also score the thrust bearing, as well as introduce excessive heat for the center section to deal with.

Oil contamination — be it from lack of maintenance, coolant or fuel in the engine oil or debris from an internal engine component breaking down — can wreak havoc on a turbocharger as well. Corrupt motor oil can lead to all of the problems mentioned above (worn journal bearings, a damaged thrust bearing, or scoring of the shaft), less the super-heating of the turbocharger’s bearings. 

SOLUTION:
Always use fresh oil and new oil filters as recommended by the engine manufacturer when fitting a new turbo. Ensure the oil is the correct grade for the engine, make sure your engine oil is changed regularly and is always free of contaminants. Clean or replace oil inlet pipes to eliminate any carbon deposits or sludge that could enter the turbo or restrict oil flow to the bearings.

4. Seal Leaks
Most modern turbochargers make use of dynamic seals (vs. carbon seals), which keep the oil being supplied to the center section from making its way into the intake (compressor) or exhaust side (turbine) of the turbo. However, things like excessive crankcase pressure in high horsepower engines, operational wear on the seals or an improperly routed (or undersized) oil return line can lead to oil leaks. Once the center section becomes overly pressurized, it can push oil into the intake and/or exhaust side of the turbo.

SOLUTION:
If you’re running excessive crankcase pressure or oil pressure due to a high horsepower application, a better crankcase ventilation system or a dry sump oiling system should be looked into. If you’re pushing oil from an old turbocharger, it may be time for an overhaul.

5.Electronic Actuator Malfunction
The VNT (Variable Nozzle Turbine) turbocharger is designed to match the size of the turbine to suit the maximum rated power of the engine, without compromising on low speed response. Latest VNT models use full electronic control of the vanes.

Movement of the vanes is controlled by the REA (Rotary Electronic Actuator) or SREA (Simple Rotary Electronic Actuator). Failure (or apparent failure) of the actuator is also a killer of the turbocharger.

SOLUTION:
Replace the electronic actuator or complete turbocharger.