Symptoms and causes of error of the turbocharger
Damages to the turbocharger can make themselves be felt in many ways, at the most frequent however by a power loss, whistling noises or production of smoke. The respective failure already then allows to draw first conclusions on possible error causes.
Power loss and boost pressure
A power loss of the engine can be frequently explained with a too high boost pressure near the turbocharger. If, for example, the pressure transducers or the boost pressure control valves fail, the boost control of the turbocharger isn't controlled correctly.
Another cause for a too high boost pressure are soot or adhesions of the guide vane, e.g. because of oil which reaches the turbine and burns there. The residues that are created in this process are the reason that the guide vanes cannot open any more. This then leads to the increase boost pressure in the turbocharger.
That the increased boost pressure makes itself felt with a reduced engine power is unpleasantly, but still makes sense. In this case, the power loss can be traced back to a mechanism which is supposed to protect the engine from damages at a too high boost pressure and therefore amongst other things drives the fuel supply back.
Other possible causes for the power loss
In case of a power loss, it makes sense to first check all filters, tubes and pipes for damages or blockage near the turbocharger. If all these components are in faultless condition, the damage might also be found in the exhaust systems or in the catalyst.
A problem with the fuel injection system is just as conceivable. If it isn't damaged itself, the settings of the fuel injection system might be the reason for the power loss.
"Whistling turbo" and other sounds
If the power loss occurs together with a whistling noise of the turbocharger, a leakage between the engine and the compressor outlet leaving of the turbocharger is a possible cause. In this case, it is necessary to check all pipe and tube systems in this area.
If there is only a whistling without a simultaneous power loss, a leak is a not quite improbable reason in the charge air cooler. The wave should also be checked, especially if the whistling sound becomes louder with increasing rotational speed: If the wave is damaged or even knocked out, mechanical friction is created together with corresponding noises that increases with increasing load.
If there occur less specific noises than the "whistling turbo" which is known in the garage, several causes can be considered: For example a too high dynamic pressure in the exhaust system, a damaged compressor or turbine wheel or a leakage at the manifold or elsewhere in front of the turbine.
Smoke development
If it smokes, one is normally shocked at first. One should nevertheless look a little more closely at the arising smoke because his color allows to draw conclusions on possible causes of the smokes development.
Blue smoke can be usually explained with oil that reaches the exhaust and burns there. Therefore, the complete oil circulation of the vehicle and thus also the turbocharger should be checked for a possible oil leakage, especially when an increased oil consumption can be noticed.
If the leakage is found near the turbocharger, the oil intended for the storage and cooling of the wave flows out. The causes for such an oil leakage are various, however, but of course should be examined nevertheless. a knocked-out wave is an example for such a cause.
Black smoke can have many causes, among other things a too low air supply while the burning. The fresh air supply and the air filter should be checked. Where a such one is available, the soot particle filter also should be checked in detail: If it is blocked, the turbocharger also can be seriously damaged in the consequence.
