Herman Rohowsky owns Cherry Turbos in St. Thomas Ontario. He’s been rebuilding turbochargers for decades, and offers a very important tip for mechanically-inclined shoppers considering a turbo car.
“The key to accepting or rejecting an older turbo is to grasp the lock-nut that holds the impeller to the shaft, and make sure the blades don’t contact the housings when rotating the assembly by hand, or moving it to one side, or in and out”.
What Rohowsky refers to is often called checking for 'shaft play'. A touch of movement in the turbine and shaft assembly may be acceptable-- but if things are 'loose' enough for the impeller blades to contact the housing they sit within, the turbo in question is toast.
Another check for turbo issues involves removing and inspecting the compressed air or ‘charge’ pipe that connects the outlet of the turbocharger to the intercooler. A thin film of oil lining this pipe can be normal, though a pool of dirty oil or signs of soot are bad news.
Note that the two above checks require some time, tools, and the removal of a few minor parts. Be careful: a turbocharger will be extremely hot after a drive, so let it cool unless you like the smell of cinged arm hair. If you're uncomfortable spinning a wrench, visit a mechanic for help.
Other warning signs of turbo problems are easier to see. For instance, worn internal turbo seals may cause thick, oily-smelling blue or white smoke to spew from the tailpipe while idling after a test drive. If the oil seals are failing, a turbo rebuild or replacement usually isn't far behind.
Poor performance and sluggish acceleration may be other indicators of trouble.
Of course, newer, unmodified, and well-maintained turbo cars leave shoppers far less to worry about. Håkan Björnsson is a Technical Expert involved with engine development at Volvo. He comments “back in the 80's when turbochargers were not water-cooled, durability was sometimes a field problem. Nowadays, turbochargers are cooled by engine coolant, so this problem doesn’t exist anymore”.
“The turbo system used today on our engines lasts as long as the engine and vehicle, and our normally-aspirated and turbocharged engines require the same level of maintenance”.
Put another way, if your potential used turbo car has all maintenance up to date and hasn't been modified, you can probably buy with confidence.
Want to keep your turbo in tip-top shape for years to come? Rohowsky recommends keeping engine oil fresh and allowing a cool-down period after driving, just to be safe. The cool-down period involves letting the engine idle a moment or two after a hard drive to help minimize turbo wear.
Rohowsky explains the importance of turbocharger cool-down. “Oil stops supporting the rotating assembly at engine shut-off while the turbo still spins for a few seconds, resulting in slight wear every time this occurs. Also, the oil "cooks" and turns into a deposit which can machine away some material or build up and seize the turbo”.
Turbocharger cool down is a common practice in some circles—though many manufacturers, Volvo included, don’t require it.
photo:Justin Pritchard, Jupiter Images
“The key to accepting or rejecting an older turbo is to grasp the lock-nut that holds the impeller to the shaft, and make sure the blades don’t contact the housings when rotating the assembly by hand, or moving it to one side, or in and out”.
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What Rohowsky refers to is often called checking for 'shaft play'. A touch of movement in the turbine and shaft assembly may be acceptable-- but if things are 'loose' enough for the impeller blades to contact the housing they sit within, the turbo in question is toast.
Another check for turbo issues involves removing and inspecting the compressed air or ‘charge’ pipe that connects the outlet of the turbocharger to the intercooler. A thin film of oil lining this pipe can be normal, though a pool of dirty oil or signs of soot are bad news.
Note that the two above checks require some time, tools, and the removal of a few minor parts. Be careful: a turbocharger will be extremely hot after a drive, so let it cool unless you like the smell of cinged arm hair. If you're uncomfortable spinning a wrench, visit a mechanic for help.
Other warning signs of turbo problems are easier to see. For instance, worn internal turbo seals may cause thick, oily-smelling blue or white smoke to spew from the tailpipe while idling after a test drive. If the oil seals are failing, a turbo rebuild or replacement usually isn't far behind.
Poor performance and sluggish acceleration may be other indicators of trouble.
Of course, newer, unmodified, and well-maintained turbo cars leave shoppers far less to worry about. Håkan Björnsson is a Technical Expert involved with engine development at Volvo. He comments “back in the 80's when turbochargers were not water-cooled, durability was sometimes a field problem. Nowadays, turbochargers are cooled by engine coolant, so this problem doesn’t exist anymore”.
“The turbo system used today on our engines lasts as long as the engine and vehicle, and our normally-aspirated and turbocharged engines require the same level of maintenance”.
Put another way, if your potential used turbo car has all maintenance up to date and hasn't been modified, you can probably buy with confidence.
Want to keep your turbo in tip-top shape for years to come? Rohowsky recommends keeping engine oil fresh and allowing a cool-down period after driving, just to be safe. The cool-down period involves letting the engine idle a moment or two after a hard drive to help minimize turbo wear.
Rohowsky explains the importance of turbocharger cool-down. “Oil stops supporting the rotating assembly at engine shut-off while the turbo still spins for a few seconds, resulting in slight wear every time this occurs. Also, the oil "cooks" and turns into a deposit which can machine away some material or build up and seize the turbo”.
Turbocharger cool down is a common practice in some circles—though many manufacturers, Volvo included, don’t require it.
photo:Justin Pritchard, Jupiter Images