A few years ago the fitment of turbochargers was only seen on high-performance vehicles and in motorsport applications, these days they are fitted on anything from your small city runabout to a double-cab bakkie.
The fitment of turbochargers became popular as a solution to reducing the carbon footprint of motor manufacturers by downsizing the capacity of the engines fitted to their product range and ensuring similar performance with forced induction systems. But these high tech components come with their own set of rules to ensure optimum running and a long life.
Normally, when an engine fails the entire engine is disassembled and checked in order to find the cause of the failure. This failure mechanism is resolved or replaced and then the engine is reassembled. Most engine rebuilds include at a minimum a new oil pump as this is one of the main causes of engine failure besides wear components like rings, pistons, valve seats or valve stem seals and the replacement of these components is relatively affordable.
When a turbocharger fails, because it is situated outside of the engine, it is normally treated as you would an alternator or starter motor and removed, replaced or repaired and re-installed. The vehicle owner thinks that the newly replaced turbocharger has had its life renewed and expects to see another 150 000 to 200 000kms of service from the new turbo. But this is not always the case.
Even though the turbocharger is physically installed outside of the engine, when it fails, it is imperative to treat it as if you were treating an engine rebuild. In order to ensure a renewed service life it is imperative to find the cause of failure, correct this cause and then repair or replace the turbocharger and re-install according to the turbo manufacturers procedures and guidelines.
During normal operating conditions a turbocharger operates at enormous rotational speeds, often in excess of 120 000rpm and at temperatures above 650 degrees celcius. The latest Euro 5 and 6 turbocharged engines are manufactured with exotic materials that allow them to safely operate at temperatures as high as 850 degrees Celsius.
“Turbochargers are critical components to an engine’s reliable operation, correct emission production and under bonnet thermal management. The turbocharger, although situated outside the engine, is fed the same oil as the engine from the very engines oil pump. The oil is fed through an oil feed line, which is the main artery feeding the lifeblood to the turbocharger, “said Chris Kambouris founder, owner and MD of TurboDirect SA.
Why do turbochargers fail?
A turbocharger is generally an extremely reliable component that will normally last as long as your vehicle’s engine, however many turbochargers don’t see this kind of mileage due to engine maintenance related issues. Lack of maintenance, late maintenance and incomplete maintenance will shorten the life a turbocharger.
The four main killers of turbochargers
Lack of lubrication is simply oil starvation to the turbocharger and normally caused by a blocked oil feed line. Over time the line that is routed very close to the extremely hot turbine side of the turbocharger, will experience high thermal loads when the engine is switched off. While the engine is off, there is no longer oil flow through the turbocharger and the stagnant oil inside the thin oil feed line will burn up and cake up inside the pipe. Over time this will start to restrict the flow of oil to the turbocharger.
Oil contamination is not just related to dirty oil, but also includes water, fuel, debris and total dissolved solids. The presence of water or fuel will compromise the oils ability to lubricate properly, resulting in gradual wear of the bearing parts and over time can result in catastrophic failure
Foreign object damage happens when foreign debris is ingested through the air intake tract and makes contact with the compressor wheel. A worn air filter is usually the cause of the damage but damage can also be caused by debris such as a broken valve seat, valve guide or piston, which is forced in its melted form out of the exhaust and into the turbocharger’s turbine stage.
Exceptional operating conditions are usually where the turbocharger operates outside of the manufacturer’s specifications, like where the turbo is forced to do so through a burst intercooler pipe or it can often be related to intentional upgrades to the vehicle. These upgrades could force the turbocharger to operate at much higher speeds and temperatures, increasing the boost or adding more fuel as a means of increasing the power output will drastically shorten the life of the turbocharger.
Turbocharger maintenance tips
- Service your vehicle on time, every time
- Use only genuine parts including oil filters, air filters and the correct grade of oil
- Allow the engine to idle for a short while to stabilize temperatures before shutting off the engine or drive the last few km’s of your journey slowly.
- Replace the oil feed line at specific intervals depending on vehicle make and application
- When replacing a turbocharger always replace the oil feed line, oil, oil filter and air filter regardless of the mileage or oil condition.
- Regularly check the operation of the PCV valve and DPF as well as the EGR valve in your car as these have a direct effect on the reliable operation of the turbocharger.
- Make sure the engines breathers are not blocked, a blocked breather will cause a turbocharger to leak oil and smoke.
TurboDirect are SA’s largest turbocharger and performance product importer and manufacturer, representing brands like Garrett, Borg Warner and Mitsubishi. They supply brand new genuine turbochargers at unbeatable prices direct to the end user, dealer and turbo repair sector.
Text: Reuben van Niekerk