By: Mike Bumbeck/autoMedia.com

The first big wave of automotive turbocharging came to auto showrooms during the Eighties. Everything from grocery getting Chrysler K-car station wagons to high-end Porsche sports cars packed a turbocharger under the hood.

 

Back in those days, it seemed a requirement that turbocharged cars could not leave the factory without the word TURBO emblazoned somewhere, if not all over the car. The fact is that a turbocharger can add performance on demand to an otherwise economy minded engine. Turbochargers are again becoming more common as consumers demand more horsepower along with better fuel economy.

 

With this ever-increasing number of cars and trucks using turbochargers as part of their power equation comes a equal number of turbochargers that will wear out and require replacement.

 

Simple in Theory

The turbocharger sits in between the engine and exhaust and takes advantage of energy that usually runs out the tail pipe and puts it to better use. Inside the turbocharger are two finned wheels that spin together on a common shaft. The hot side turbine wheel captures the power of exhaust. The cold side compressor wheel takes the energy captured by the turbine wheel and uses it to force air back into the engine. The air is then mixed with fuel and presto - the puny four-cylinder Chihuahua of an engine suddenly makes like a Doberman V8. Since the compressed air forced into the combustion chambers contains more oxygen, the engine can make more power than it could by breathing without the turbo. When the additional power isnt needed the turbo simply spins along for the ride and lets the engine take it easy and realize economy.

 

Care and Feeding

While the turbocharger itself is a relatively simple device, replacement can be an expensive reality. A new replacement turbocharger can run into the multiple thousands of dollars not even counting installation and labor. The way to avoid premature turbo failure is to follow manufacturers motor oil and service recommendations to the letter.

 

Turbochargers can be brutally tough on motor oil. The same exhaust that spins the turbine wheel gives the hot side its name. The hot side housing can literally get red hot. Since the shaft can spin in the 100,000 revolutions per minute range oil is key to turbocharger survival. Advances in both motor oil and water-cooled turbocharger housings have made turbocharged engines more consumer friendly than ever, but neglecting motor oil can still spell the end of a turbocharger before its time.

 

In the Balance

The price of a new replacement turbocharger can be staggering. If the turbocharger failure isof the normal wear and not the exploded in a screeching underhood grenade variety then rebuilding may be an option. The bad news is that rebuilding a turbocharger is beyond the scope of most home do-it-yourselfers.

Disassembly and inspection might be possible but any machining and balancing requires both specialized machinery and experience. The good news is that there are professionals to handle the job. A turbocharger rebuilt with fresh bearings and seals can live on to serve for many miles at considerably less cost than a new replacement unit.

 

Step One: The turbocharger is disassembled. Oil can become so hot inside a turbocharger that it cooks and leaves carbon behind. The carbon then clogs oil passages and restricts oil flow. Restricted oil flow is very bad news to the turbocharger.

 

Step Two: Parts are cleaned and inspected. Measuring of inside housing diameters and outside shaft diameters will determine which parts can be reused and which need replacement. Cracked exhaust housings are an item that will require replacement.

 

Step Three: Balance is everything. Even the slightest bit of imbalance can cause a turbocharger assembly to come apart - or grenade. The compressor and turbine wheels are balanced individually and then the entire assembly is balanced.

 

Step Four: The turbocharger cartridge is assembled with new bearings and seals. The shaft spins on a thin layer of oil just like the crankshaft in an engine. Worn bearings cause excessive shaft play. Oil can escape past the seals. Clouds of blue smoke on boost could explain where all that oil is going.

 

Step Five: The turbocharger cartridge is put back in between the hot and cold side housings. With assembly complete the wastegate actuator is pressure checked to see if it opens the internal wastegate at the correct pressure.