Turbochargers were once a cool new unexplored technology. The addition of a turbocharger to an early Porsche 911 transformed your dentist’s car into an infamous snap-oversteer death machine. Mitsubishi was so proud of the Starion ESI-R that the interior was covered in now-outdated TURBO logos. The Ford Mustang SVO ditched the iconic “five-liter” V8 in favor of a 2.3L four-cylinder from the Pinto with a Garrett turbo, and it was faster. This was simply a preview of the 2015 Mustang EcoBoost, which has more power than a V8-powered 2010 Mustang GT.
Turbocharger Boost Adds Horsepower
Decades later, the technology has matured to the point where it can be found in everything from sports cars to diesel trucks to any compact sedan or family SUV. When Chevrolet first introduced the compact Cruze sedan in 2011, the optional 1.4L turbocharged engine produced roughly the same amount of power as the base non-turbo 1.8, but it improved in torque and MPG. The Ford F-150 pickup’s V8 engine has been largely replaced by a twin-turbo V6. Turbo failures are becoming more common as this technology makes its way into more mainstream vehicles with higher mileage and possibly more lax maintenance routines. But just because it’s new technology doesn’t mean it has to be difficult.
Disconnecting the battery is only for safety, but if your turbo has an electronic actuator or bypass valve, it will be beneficial for the computer to reset with the new part connected. An oil change is recommended because disconnecting the oil return line that drains into the pan could cause a mess. Remove the intake piping and clean out any residual oil that may have leaked from the center section of your old turbo.
Cleaning the intake on your diesel vehicle is critical to avoiding “runaway diesel.” While gas vehicles have a throttle body to limit the amount of air that enters the engine, diesels do not. If you start your diesel engine and the air going into it is contaminated with used oil, the engine will burn the oil as if it were fuel, and you won’t be able to turn it off unless you can cut off the engine’s air supply. Although residual oil is less important in gas vehicles, it can still cause smoke from the exhaust, which can damage your oxygen sensors and catalytic converter, and any metallic debris from your old turbo can damage the new one or your engine’s cylinder head.
Oil lines should be disconnected and cleaned/replaced. The most common cause of turbo failure is insufficient oiling. If you skip oil changes or use the incorrect viscosity, the oil lines can become clogged with sludge or baked-in carbon, starving the center bearing of your turbo. You can clean your oil lines with a carburetor cleaner and compressed air, but it’s better (and not too expensive) to replace at least the oil feed line, if not the return line.
Disconnect all vacuum lines and electrical connectors. Label everything with tape and take a picture of your turbo setup before disassembly to make it easier to reconnect everything when you’re putting the car back together!
Remove the old turbo from the exhaust manifold and downpipe by unbolting it. This is usually the most difficult aspect of the job. Some of these bolts are difficult to reach, and after years of heat cycling, they may be difficult to free or fragile enough to break off if you are not careful. If your new turbo has an integrated exhaust manifold, you’ll most likely need to replace the exhaust studs because the originals are a one-time-use item. To ensure a clean seal for the new part, clean all mating surfaces and remove any leftover gasket material. This is an easy place to cut corners, but a boost or exhaust leak will cause drivability issues, so doing it right the first time is preferable. Add a few drops of oil to the new turbo’s line ports and spin the turbine wheel to ensure the new turbo bearing is primed and lubricated before starting the vehicle.
It is critical to ensure that the center bearing of your new turbocharger is completely coated in oil before the first startup. Even at startup, this bearing spins at thousands of RPM. To be extra safe, after reassembling everything, pull the EFI relay and turn the key a few times to turn the engine over without starting it, and activate the mechanical oil pump for a few rotations. Install new gaskets and connect the turbo’s exhaust side to the manifold and downpipe. Check your factory service manual to see if any torque specifications must be followed.
As needed, reclock the compressor side of the turbo. This is usually required for turbos that are designed to fit multiple vehicle applications. Once the exhaust side of the turbo is fully bolted in place, loosen the band or snap ring that secures the compressor housing to the center section and rotate it until the compressor outlet is facing the correct direction to connect to the charge pipe. Most turbos can be re-clocked in this manner, though some require multiple bolts to hold the compressor housing in place.
All oil lines, vacuum lines, electrical connectors, and intake piping should be reconnected. Reconnect the battery, restart the vehicle, and fine-tune the wastegate actuator as needed to meet factory specifications.