572,000 Sonata and Santa Fe Sport vehicles are being recalled because the Theta II engines can seize at any moment.
Hyundai says machining errors occurred when the engines were built and those errors can cause the engine bearings to wear out early. Those prematurely worn bearings will cause the engine to lock up, something a dealer will need to fix by replacing the engine short block.
Hyundai admits that two errors made during manufacturing are responsible for the problems:
- Metal debris left over during machining the engine crankshaft wasn’t completely removed during the cleaning process.
- Another machining error left uneven surfaces on the crankpins.
From there it’s only a matter of time before the debris is grabbed by oil → the oil starts to clog up → the reduced flow affects the connecting rod bearings → heat and friction rise → the bearings wear out prematurely → horrible knocking noise ensue.
Kia is recalling 618,000 vehicles for the same problem.