Head gaskets have a tough job sealing combustion pressures in diesel engines because of their high compression ratios and boost pressures. Diesel engines are typically low revving, high torque motors that are designed to last several hundred thousand miles.
According to my experience, I estimate that replacing the alternator solves 95% of all charging system failures. If that's true, what happens in the remaining 5% of charging system failures that results in customer comebacks?
The prices of rotors seem to be dropping the past few years. Call just about any parts supplier and they can quote you a vast range of prices for the same application. And when you compare the rotors side-by-side, they may look the same, but the difference between a comeback and a satisfied customer is often at the microscopic level.
Air filters are normal wear items that require regular checks and replacement. Their role is to trap dirt particles that can cause damage to engine cylinders, walls, pistons and piston rings. In fuel-injected vehicles, the air filter also plays a role in keeping contaminants off the airflow sensor.
If a Kia comes in with a grinding problem, the next step is to look for uneven wear. If one wheel is showing more wear than the other on that axle, it's time to do some investigating. The most likely cause of unexpected wear is a caliper or hardware issue, and the key to a successful job is figuring out the true culprit.