A friend recently had to check-in his Diesel Turbo AUV(Asian Utility Vehicle) in a service shop. He complained about the lack of acceleration and the excessive black smoke that it spewed. The diagnosis was later served with figures that were off the charts - a busted turbo.
In my article a few months back entitled “Turbocareâ€, I enumerated essential tips to maintaining a turbo engine. In this article, I will stick to the usual suspects to premature turbo failure.
Proper Lubrication
The biggest area of concern in the turbo is the oil supply. Insufficient oil or dirty oil may wear out the turbo bearings, causing wear and shaft play in the turbo. The high degree of temperatures that the turbo operates on will cause the oil to break down faster than a comparable non turbo car. Synthetic oil is highly recommended for turbo cars because it doesn’t break down as quickly as conventional oil. Diesel engines inherently are grimy fuel burners, the meaning of which is defined in the way it produces black smoke. The residuum of this combustion , which remains in the engine, is then picked up by the oil. This explains why oil in diesel engines degrade faster than in gasoline engines.
Shutdown Procedure
Since the turbo gets hot when running, an engine idling period of 10 seconds before every engine shutdown is enough to let fresh oil circulate to the turbo bearings. If you were driving in traffic for long periods or you had a hard journey up the mountains, a 1 minute idling period (engine running stationary) should be enough to let the turbo cool down and receive fresh oil. If the turbo is too hot and does not receive cooler oil upon shutdown, the oil could become burnt and “cooked†in between bearings causing clogging in the lubrication paths.
Some people install a turbo timer to keep the engine idling so they can walk away from their car during a cool down procedure. This is a convenient way of automating engine shut down procedure although it is not necessarily needed. The downside is that a turbo timer requires purchasing a timer, cutting wires and introducing an unnecessary failure point.
Cooling System Maintenance
Lastly, excessive heat is a deadly foe that kills engine internal parts. Turbos are designed with oil and/or water jackets for lubrication. The oil jacket is where oil passes through not only to lubricate shafts and bearings but also to cool down the parts. The use of fully synthetic diesel grade oil is a must as it is more resistant to heat.
Some turbos have water cooling jackets that draw water from the engine’s cooling system. The problem arises when the cooling parts of the engine are corroded like the radiator. Rust particles will find their way to the turbo water jackets, clogging the system with rust particles. This will cause the turbo to overheat and eventually fail. It is best to do a periodic flush of engine coolants every 10,000 kilometers. The use of radiator coolants will also aid cooling as it acts as an anti-boil/anti corrosion additive.
Leaks to both oil and water cooling systems will decrease pressure and jeopardize the efficient flow of coolants, not to mention oil/water starvation resulting to, most likely, a very expensive turbo fix.