We are about to purchase a used BMW 328i. Everything looks ok, except part of rear tires has very bad rusty. Is that ok? The rusty part looks like: https://www.pelicanparts.com/BMW/techarticles/E36-Brake_Pads/pic14.jpg
Pay an independent mechanic to inspect the car prior to purchase. Beemers are expensive to repair.
The picture showed what APPEARS to be normal surface rust.
Rust on brake rotors can happen overnight. Not a big deal. Make sure you have the budget to keep this thing repaired. It’s gonna be a lot more expensive than a normal car.
Why anyone would buy a 2016 MY BMW and not get a certified pre-owned one is a mystery to me. The upside is huge and the premium is not that much, particularly given this is a “premium” vehicle. That said, rust on rotors is no big deal. I’m guessing the full MFG warranty is just recently up on the vehicle, but it may not be. Worth a close look.
GorehamJ, thank you for the comment. It is BMW certified pre-owned, but that rust on rotors (hubs) are not covered in warranty. I just wonder will there be any safety issue? Will the situation get worst and becomes a problem.
Not before you need to replace the rotors because they’re worn out anyway. Rotors are made of cast iron. Ever put a cast iron pan in the dishwasher? It rusts instantly because the dishwasher strips the protective layer of polymerized oils off of the pan. Unprotected cast iron rusts very quickly. It’s not unusual to wander through a new car lot and see rust on the brand new rotors.
There isn’t much point to protecting the cast iron on a brake rotor - the protection would flake off sooner than later, and surface rust on a rotor doesn’t hurt anything anyway so why bother?
It’s completely normal, most of it will scrub off when you first use the brakes. As long as the rotors don’t get pitted you’re fine. Carbon Ceramic rotors get around the issue but at a huge premium.