Common Turbo Faults and How to Spot Them
The turbochargers bearings depend on a constant flow of clean oil to function properly. Several factors can lead to the break down of the oiling system, lack of maintenance, improper oil or filter, severe driving conditions, or in most cases simply the age of the vehicle can contribute to degradation of the turbochargers supply of oil. We recommend changing your oil and filter any time the oil starts to change from its original golden brown to a darker brown colour regular oil and filter changes is critical to the life of the turbo.
Today’s newer engines run very high water and oil temperatures to help with emissions and fuel economy. This heat is very hard on the oil, causing it to break down on a molecular level resulting in having a reduced ability to provide lubrication and viscosity. The increased heat is also compounded when you shut down your engine and the car is allowed to heat soak. Along with frequent oil changes it is also advisable to allow the car about one to one and a half minutes of idle time before the engine is turned off if you have been driving at higher speeds.
Foreign objects entering either the compressor inlet from the air filter system, or through the turbine inlet coming out of the engines combustion chamber. Any time you service your air filter, be sure to thoroughly inspect all of the system for loose connections or any small amounts of dirt, leaves or other debris that might accidentally enter the air filter housing. The compressor wheel in every turbocharger is very delicate, and any trash left inside the housing will be immediately detrimental to the turbochargers operation. On the turbine side of the turbocharger the only user serviceable items that could be potentially harmful will be the spark plugs and possibly any pre turbocharger oxygen sensors.
If there is a leak between the compressor and the engine, proper pressure will be harder for the turbocharger to obtain; the waste gate will remain in the closed position until the turbocharger overcomes the leak and provides pressure within the intake manifold. Even a small leak can cause the turbo to work 20% harder than normal to reach its desired pressure, so great care should be given to the plumbing system on the pressure side of the turbocharger. Inspect all hoses and fittings for fitments and tightness, looking closely for piping that could rub and wear holes that could cause leaks. Also inspect the inter cooler core and compressor, bypass valve, if equipped for proper function.
The exhaust system after the turbocharger needs regular inspection. Increased back pressure due to clogged or damaged catalytic converters, resonators or mufflers will decrease the flow out of the engine and also raise the temperature inside the turbochargers exhaust housing, which contributes to the oil coking and also raises the risk of gasket failures or cracks in the exhaust manifold and turbine housing area. Usually this only occurs in older cars, or with higher mileage cars. 10 years or 100,000 miles is an average life span of most modern exhaust systems.
Also, oil leaks in a turbocharger may be the result of the crankcase breather system. Either atmospheric or positive ventilation systems may not be large enough to handle the somewhat higher blow by which exists in turbocharged engines. It is recommended that the engines breather capacity be increased when a turbocharger is added. Even when the systems capacity is adequate, the elements in the systems breather will become partially clogged through use. Also, the breather may become clogged with mud or sludge in winter or under snowy and icy conditions. These conditions will cause positive pressure to build up in the crankcase. If this occurs, it will restrict the oil from flowing down the drain hose and into the crankcase, causing it to back up to the bearing housing.
Some naturally aspirated engines have internal positive crankcase ventilation between the crankcase and the intake manifold. These vents must be plugged when a turbocharger is added, otherwise the crankcase will become supercharged and oil leakage will result. Another source of crankcase breather must be provided when these vents are plugged. Some engines have this extra breather, while others may not. In either case, make certain that the breather’s capacity is adequate.
In addition to the causes listed above, excessive exhaust gas temps (EGT’s), moisture ingress, wear and tear, fuel intake systems, the waste gate and the exhaust system can also cause damage to your turbocharger.
The warning signs
There are several ways that your vehicle will let you know that its turbo is in need of maintenance or repairs:
On most modern cars, the computer diagnostics will pick up turbo faults and the check engine light will come on. Of course, the check engine light doesn’t just cover turbo failure, and you will need to do some further checks to see what kind of engine problem you have.
Some turbocharged vehicles are fitted with a boost gauge, which lets you how much boost your turbo is producing (you can also fit one to your car if desired). If your boost gauge isn’t going up as much as it used to, then there is a good chance your turbo is in need of repair.
If you notice that your turbocharged vehicle is accelerating more slowly than usual, or isn’t capable of reaching the speeds it once could, this may be a sign that your turbo is failing.
If the turbo housing has cracked, or the internal seals have blown, oil will start to leak into your exhaust system. As this burns off, it produces a distinctive blue/grey smoke, which will probably become more apparent as the engine revs increase just following an idle situation.
Often, a failing turbocharger will make a loud, distinctive noise when under boost. If you start to hear this noise from your engine, it’s definitely time to have it checked out!
The next steps - checking your turbo
If you notice any of the warning signs, then get your turbo checked as soon as possible. Your turbocharger is not going to repair itself, and the longer you leave it, the worse (and more expensive) the problem will get!
To help minimize the risk of turbo failure, here are some helpful tips you can follow:
- Change the oil in your vehicle at least every 3000 miles.
- Always use oil that is recommended by the manufacturer of the engine.
- Do not use cleaning additives, these may loosen particles and other debris.
- Always let the engine warm up when you start. A recommended time is 30-60 seconds in warmer weather, and longer as the temperature drops.
- Remember, cold oil is thick, and doesn't flow as freely as warm oil.
- Do not rev your engine during the warm up, the turbo may not have had enough time to receive a full supply of oil.
- When stopping, let the engine idle for a period. The faster you were driving, the longer your idle down time should be.
- Remember, the turbo is free spinning at high RPMs, and when the engine is shut off, so is the oil supply. If the engine is not properly idled down, the turbo may experience bearing damage.
- When you do change the oil, remember to prime the filter and crank the engine without starting until full oil pressure is observed.