Subaru Outback Forester

Case Study: The TR690 Noise That Two Shops Blamed on Tires

By Dave at Gearbox Insider

2017 Subaru Outback 2.5L, TR690, 103,000 miles. Customer complaint: droning noise at 45–65 mph that had been present for about four months and was getting louder. Two previous shops had both recommended tire rotation and balance. One had also suggested an alignment. Neither had resolved the noise. The customer described the noise accurately: constant drone that changed with vehicle speed but not with engine RPM or steering input. That description alone rules out wheel bearings (which change with steering load) and tires (which produce more of a tread pattern hum that varies with road surface). A noise that is strictly speed-dependent, consistent across all steering inputs, and independent of engine RPM on a Subaru with a CVT has one likely source: the secondary pulley bearing.

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TR690 Secondary Pulley Needle Roller Bearing — OEM Spec Replacement

The primary mechanical failure item on high-mileage TR690 units — fine gray metallic particles in drained CVTF combined with a speed-dependent drone is the diagnostic signature.

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