The most common symptoms related to lack of turbocharger performance are lack of engine power, excessive exhaust smoke from excessive oil consumption, and (if applicable) the ingestion of coolant from a water-cooled bearing housing.

When dealing with a lack of engine power, first determine if the engine is operating correctly before blaming the turbo for causing the issue. If the engine runs well, then there is an excellent chance that the cause of the lost power or excessive exhaust smoke is in the turbocharger system.

When setting out to determine what’s making the turbochanger perform badly, always conduct a physical examination of the component. Check all inlet connections for a tight fit from the turbocharger to the engine. Loose hose clamps or compromised hoses will let boost escape.

During your examination, look for telltale signs of an exhaust leak upstream from the turbine housing back to the engine.

Exhaust leaks limit turbo performance since not all the exhaust gas is flowing to the turbocharger’s turbine. This, in turn, greatly affects its ability to compress combustion air.

When looking at the system, be sure to check the integrity of the turbocharger’s intercooler (CAC). It’s possible for it to get a crack in a tank or a small pin hole in a tube (particularly a problem in over-the-road vehicles). It may be necessary to remove the CAC and pressure-check it as you would a radiator.

If an oil seal on a turbo’s compressor does go bad, it will force lubricant into the CAC. Wash that lubricant out since it not only causes excessive exhaust smoke but also limits the thermal conductivity of the unit.