As someone who puts extreme mileage on vehicles, often exceeding 100,000 miles annually and sometimes 20,000 miles in a single month, my experience with car parts differs significantly from the average driver. Parts on my vehicles tend to wear out from use rather than age. This means I often see much higher mileage from components compared to what manufacturers might expect under normal driving conditions.
I own two 2017 Kia Niro FE models. My red Niro, which has clocked an impressive 423,000 miles, was still running with its original tensioners in good condition until recently. I did replace the serpentine belt at 378,000 miles, along with the spark plugs, which were worn but still functioning. Interestingly, the hybrid battery gave way at this point, and finding a used replacement with 171,000 miles proved to be a more cost-effective solution than the dealership’s quote for a new battery – a strange situation where the replacement battery itself cost less than the quoted labor.
My black Niro, with 244,000 miles in just seven months, recently started exhibiting a squealing noise. This wasn’t a constant squeal, but rather two quick chirps that occurred when the engine shut down during its normal hybrid cycling. The noise had been present for about 20,000 miles before I finally had the chance to investigate and replace the belt.
Upon inspection and removal, I discovered the lower tensioner shock had completely failed. It essentially fell apart in my hands. I plan to share some images soon to illustrate the extent of the damage to this component.
The failure seems to stem from a small shaft on the upper part of the shock that guides into the lower piece. This shaft had become dislodged from its guide, causing misalignment between the upper and lower sections. I believe this misalignment led to the tensioner shock locking up, ultimately snapping the lower attachment bolt and leaving a fragment embedded in the tensioner arm. This also resulted in the shock rubbing against the arm instead of pivoting correctly on the bolt.
Since Kia doesn’t sell the shock assembly separately, requiring the purchase of the entire arm and shock assembly, there was no need to attempt extracting the broken bolt piece. Despite the 20,000 miles of squealing, the old serpentine belt itself was still in surprisingly good condition. However, having a spare belt on hand, I proceeded with a replacement anyway. The new tensioner assembly is on order and expected to arrive in a few days.
I am genuinely interested in understanding the potential causes of this tensioner failure, especially given the high mileage context. Has anyone else encountered a similar failure with their Kia Niro or other vehicles? Any insights or experiences you can share would be greatly appreciated.
