The Theta II's rod bearing failure is one of the most documented engine defects of the decade — and many cars qualify for extended warranty coverage. We confirm your eligibility first. If you're outside coverage, we replace the short block at your home.
The Theta II 2.4 in the Sonata and Santa Fe Sport has a factory defect, not a maintenance problem: machining debris left in the crankshaft oil passages during manufacturing restricts oil flow to the connecting rod bearings. Starved of oil, the bearings wear their soft overlay away, the clearance opens up, and the rod starts hammering the crank journal — that's the knock you hear under acceleration, when cylinder pressure loads the bearing hardest.
Once a rod bearing starts knocking, the countdown is short and the failure is total. The bearing material breaks up and circulates as metal in the oil — visible as glitter on the dipstick or in the filter. The end state is a spun bearing or a seized engine, sometimes with a rod exiting the block. This defect is why Hyundai faced a class-action settlement, extended warranties on qualifying VINs, and rolled out the knock-detection software (KSDS) that puts cars into reduced-power mode when it hears bearing knock.
Here's the part most shops skip: because of the settlement, a knocking Theta II might be Hyundai's bill, not yours. Coverage depends on the VIN, the documented symptoms and the car's history — and it's worth checking properly before anyone charges you for an engine. We do that check first, every time. If your car genuinely falls outside coverage, the fix is a replacement short block, and we do that at your home rather than a shop holding your car for weeks.
If your Hyundai is doing any of these, this is the likely cause:
A knocking rod bearing is days-to-weeks from total failure, not months. Driving on it grinds bearing metal through the entire oil system and risks the rod letting go through the block — which can take the car from repairable to scrap. If your Theta II is knocking: stop driving it, get the warranty check done, and decide from real information. The knock never gets quieter.
Yes — with the right preparation. We need a level paved surface and space to work an engine crane beside the car, and the job spans two days. Everything else — the block, fluids, tooling — arrives with us. It's a major job, but nothing about it requires a building.
An engine replacement is days of book labour plus a factory short block at dealer pricing — the numbers compound fast. But on this specific engine, the first question isn't price, it's coverage: the settlement and extended warranty exist precisely because of this defect. We check your VIN's eligibility first, and if you do have to pay, we quote one flat price for the complete job before any work starts.
Coverage ties to the VIN, the documented failure and the car's history — the class-action settlement extended rod-bearing coverage on qualifying vehicles well past the original warranty. We run that check as step one and tell you honestly what we find. If Hyundai should be paying for your engine, you'll hear it from us before you spend a dollar.
Possibly, and we confirm before quoting: rod knock has a distinct character under load, and an oil filter inspection for metal settles it quickly. If your noise turns out to be a pulley or shield, you'll get that diagnosis and a much smaller repair — not an engine you didn't need.
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