Edmunds Answers

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  • MrShift@Edmunds 09/27/11 1:05 pm PST

    I wouldn't let it bother me. That's what warranties are for. Turbos are very precise devices and requiring precision machining. One little error in manufacture and at the speeds that turbo spins, it's toast. GM probably didn't make the thing anyway.

  • zaken1 09/27/11 2:27 pm PST

    The fact that one component on the car failed at a low mileage is not in itself a cause for concern. There are thousands of parts on cars, and every one of them is subject to manufacturing defects. A small percentage of these parts will fail during initial use. The manufacturer provides a warranty in order to cover this statistical risk. Ordinarily, after a defective part is replaced; the rest of the vehicle should be unaffected by the incident.

    However; in this particular situation; there is one potentially major consequence which could have been caused by the turbo failure. The turbocharger contains a fan like device called an impeller which rotates at extremely high speeds. This impeller is supported by roller bearings. It sounds like one of the bearings siezed, and stopped the impeller from turning. In this situation; if the bearing degraded sufficiently to allow the impeller shaft to wobble even a few thousandths of an inch, there is some possibility that a fragment of the impeller could have broken off and then was sucked into the engine through the air intake system. Even a tiny shard of metal that got into the engine could gouge a cylinder wall or damage a piston. And that would reduce the compression, cause a loss of power and rough running, and lead to increased oil consumption. There is no certainty that this happened or did not happen; but it is a significant possibility.

    If the damage was initially small enough; it would be likely to go unnoticed by the mechanics. But this type of problem will inevitably escalate over time. There is a very sensitive diagnostic test called a cylinder leak down test which would be capable of detecting such a problem. The dealership could run this relatively inexpensive test if they had the equipment and were sufficiently motivated. In my opinion; this would be a prudent and responsible thing to do here. But they may or may not be willing to do it.

    If you are concerned about this possibility and the dealership either does not have the equipment or refuses to perform this test; I would locate a reputable independent local shop which has a cylinder leak down tester, and pay them to perform the test. If the test indicates abnormal variation in cylinder pressure leakage; have the results documented by the shop in detail on their invoice. Then contact the regional GM Customer Service Center and demand that the engine be replaced under warranty.

    If you would like a recommendation for a qualified independent shop in your area, please click the "answer this question" button, type your city and state in the box that appears; and click the "submit answer" button. I will try to find such a shop in your area.

    For your information; vehicles equipped with turbos generate extreme heat on the turbo shaft bearings; and this unique characteristic requires a specific procedure when shutting the engine off, in order to avoid bearing damage. Vehicle manufacturers at one time posted advisory notices in turbo equipped vehicles warning the operator to always allow the motor to idle for two full minutes before shutting the motor off. This allows sufficient time for the turbo to cool and the bearings to receive proper lubrication. I don't know whether they still do this; or whether public relations people have now pressured manufacturers to hide this warning in the owners manual. But it is a real necessity on this type of vehicle. Furthermore; the adoption of energy conserving (read; diluted) motor oils in all new vehicles has degraded lubrication capability to the extent that turbo equipped vehicles are particularly prone to bearing problems when using this borderline suitable oil. I would look at the label on the oil which is being used in your car; and confirm that it says "turbo approved" on the can. If it does not say "turbo approved' that oil should not be used in a turbo motor. Some dealers do not bother to make such distinctions in the vehicles they service.

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