More car owners have been using turbochargers in their cars in recent years. They’ve been placed in a variety of vehicles such as factory Ford Mustangs, diesel pickups, and big-block streetcars. Inevitably though, turbochargers can have some failures. In some of the most extreme operating environments, insurance items such as blow-off valves, 360-degree thrust bearing assemblies, and ball-bearing center cartridges may not be able to protect turbochargers from reaching their breaking point. Here are seven common causes of turbocharger damage that you need to avoid.
1. Damage by foreign objects
If your turbocharger ingests things such as a bolt left in the intake, dust, dirt, or shop rags, it can be disastrous. A majority of all turbo failures occur when debris makes its way across the blades of a compressor wheel. The leading edge of your compressor wheel’s blades will indicate some impact from the object or objects. The inducer bore, where the compressor wheel sits in, can show signs of scarring or contact. The cause of debris entering a turbo is usually the result of a dirty air filter. Make sure you’re running a quality air filter that has outerwear. Keep the filter clean if it’s reusable. If it’s not, install a new one that’s at the proper interval.
2. Overspeeding
When a turbo is pushed out of its compressor map, it will create excess drive pressure. That will cause the shaft to see more speed than it’s designed to handle. When you overspeed, the turbine wheel will usually be the first to give way to the pressure. They may even come apart and exit the tailpipe. Overspeed scenarios tend to be most common on high-performance diesel. Modern diesel pickups can get 30 psi of boost or more. At this level, it won’t take much in terms of power-adders to exceed the limits of the OEM charger. You can avoid overspeeding by keeping your turbocharger’s boost-to-drive pressure ratio as close to 1:1 as possible. You might have to run a wastegate to bleed off excess drive pressure. An additional thing you’ll have to consider is opening up the exhaust flow through a larger turbine housing.
3. Issues with oiling
If your journal bearing turbocharger isn’t properly lubricated, the bearings will be killed. At extended periods of time with a lack of oil supply, the journal bearings eventually begin allowing shaft play, and then the compressor or turbine wheel makes contact with its respective housing. Inadequate oil supply can also score the thrust bearing and introduce excessive heat for the center section to withstand. It’s recommended that you use a -6 AN oil supply line on larger-frame turbos, so appropriate oil flow is consistently on tap. Oil contamination can also cause all of the problems mentioned above, and less the superheating of your turbocharger’s bearings. For that reason, you need to regularly change the oil and make sure it’s free from any containments. Always run no smaller than a -6 AN oil supply line.
4. Seal leaks
Dynamic seals are more common in modern turbochargers than carbon seals. They keep the oil that’s supplied to the center section from getting into the exhaust side of the turbo or the intake. Nonetheless, operational wear on the seals, improperly routed oil return lines, and excessive crankcase pressure in high horsepower engines can lead to oil leaks. When the center section becomes too pressurized, oil gets pushed into the exhaust side of the turbo or into the intake. If you’re running excessive oil pressure or crankcase pressure because of a high horsepower application, you should look into a dry-sump oiling system or a better crankcase ventilation system. If the oil is being pushed from an old turbocharger, it might be time for an overhaul.
5. Failure with thrust bearing
You’ll find the thrust bearing located near the compressor wheel. It’s designed to limit end play, which should be between 0.0002 to 0.0004 inches. It rides on a thin film of oil between it and the shaft, and because of that, it’s necessary to make sure the bearing has no contact with the shaft. When contact occurs, thrust bearing failure will usually be imminent. Once your thrust bearing is gone, wheel-to-housing contact will soon follow. Anytime turbos are fitted with aftermarket compressor wheels, a thrust bearing’s lifespan can be considerably shortened. Among the best ways you can improve your turbocharger’s durability is by adding a 360-degree thrust bearing. It will provide a full circle of oil lubrication around the shaft. If you’re purchasing a new unit, you can specify that it has a 360-degree thrust option.
6. Surging
Surging is also sometimes referred to as turbo bark or chirp. Compressor surge happens when intake air reverts out of your compressor. It’s often experienced when an elevated boost is produced and cut off abruptly, such as when you suddenly lift off the throttle. The noise you’re hearing is the compressed air trapped in your intake and having nowhere else to go, but back out the way that it entered the turbo. Surging can be very difficult on the compressor end of your turbo. If surging is done for a prolonged period of time, it will eventually beat your thrust bearing to death. Typically, blow-off valves are used in high-surge applications. If the surging is violent enough, you risk the compressor wheel exploding. The way to prevent this problem is to make sure your engine has a properly sized turbo. Avoid using one that’s too big to ensure that at low rpm, you’re staying above the surge line.
7. Extreme
Turbochargers exposed to 2,000 degrees Fahrenheit of heat can take a toll on the turbine side of the turbo. It can cause the turbine inlet volutes to have eroded edges and the turbine inlet to have stress cracks. Restricted exhaust systems, clogged air filters, high performance, and cracked intercoolers are usually the cause of excess heat being generated. You can install a pyrometer gauge to monitor exhaust gas temperature and stay within your particular engine’s recommended heat threshold.
Turbochargers are an exciting addition to have in any vehicle. Proper maintenance and careful use are key in preventing all of these common causes of turbocharger failure. You can learn more information about turbochargers at this link: https://goldfarbinc.com/.
