Downsized, force-fed engines are often used to replace larger naturally aspirated units, a strategy that on paper tends to be more economical. But oftentimes these powerplants are more complicated than the ones they’re substituting, with intercoolers, extra oil lines, convoluted plumbing and more potential headaches down the road.
Should you worry about owning a car or truck that’s turbocharged as more and more vehicles make this powertrain switch? For answers we reached out to some folks that closely monitor vehicle quality to find out what’s really going on out there.
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Putting major fears to bed, Michael Karesh, developer of TrueDelta.com said, “I’m not seeing many turbocharger failures, at least not yet.” His quarterly quality survey includes responses from nearly 100,000 participants.
“A typical failure rate for a turbocharger is probably around one or two percent,” he said. According to Karesh, many of his participants’ vehicles typically have fewer than 100,000 miles on their odometers. He doesn’t have much data for cars that have gone farther than that. Still he said, “I would of expected [the failure rate] to be higher.”
In the TrueDelta survey turbocharged engines are generally pretty reliable but there are a few exceptions. “The main case [that] stuck out as being much higher than others was the 2008 BMW 535i,” said Karesh. This was the “first year of the turbocharged engine in the 5 Series.” Karesh said about one in six of these 535i models has had turbo-related issues over the past two years, though he cautioned that his sample size is small. Still, “It’s not a fluke, either,” he said. Curiously he said the failure rate in the 335i, which for the same year featured an identical engine, only has about a two percent failure rate.
Given their reputation for outstanding quality and reliability it was surprising that a couple turbocharged Japanese vehicles popped up in Karesh’s survey. Compared to the abovementioned 5 Series he said, “At about half that we have the Mazda CX7 [from] 2007, which everyone knows is a really bad engine … It’s a known horror story.”
But Mazda isn’t alone. “The other one that stuck out was the 2004 Subaru Forester XT, which is the first year for the turbocharged Forester,” said Karesh. “Unlike other vehicles in the survey they have a lot more miles on them.”
According to Karesh the issue with these cars is a small filter in the oil line that runs to the turbo. If it ever gets plugged with sludge or other detritus the blower can be starved of lubricant and fail. “A lot of people go and remove the filter preemptively,” said Karesh, preventing this issue. Fortunately Subaru appears to have corrected it in subsequent years.
The final sore thumb in TrueDelta’s survey is a Volkswagen. Karesh said, “And then the fourth car is the 2012 and 2013 Passat TDI.” He has reports of multiple turbo failures, three for one year and five for another. Again, the sample sizes are small but he said this indicates there is an issue with these models.
Ford has been a major player in the downsizing, turbocharging movement with their EcoBoost line of engines. When asked about these powerplants Karesh said, “I don’t think I’ve had any reported turbo failures in those yet,” but he cautioned that these vehicles aren’t that old yet ...