O'Fallon Auto Repair

When it comes to car maintenance, some components hog the spotlight—oil changes, brake pads, spark plugs—while others quietly do their job behind the scenes. One such unsung hero? The PCV (Positive Crankcase Ventilation) valve. This little gadget plays a crucial role in your engine’s health, and if it fails, it can cause some surprisingly expensive problems. What Does a PCV Valve Do? Your engine produces blow-by gases—a mix of unburned fuel, oil vapors, and exhaust—that can build up inside the crankcase. Too much pressure can lead to oil leaks, sludge buildup, and even engine damage. The PCV valve’s job is to redirect these harmful gases back into the combustion chamber to be burned off, reducing emissions and keeping your engine running smoothly. Why Is It So Important? A failing PCV valve can cause: Sludge buildup – Clogged oil passage ... read more

Your car’s battery is like the heart of its electrical system—it powers everything from your headlights to your infotainment system. But when something goes wrong, that heart can get drained fast, leaving you stranded in the O’Fallon Walmart parking lot with a dead battery and a bad mood. At Hillside Auto Repair, we’ve diagnosed more parasitic drains than we can count—and we know exactly how to track down the culprit before it leaves you calling for a jump start. How Your Car’s Electrical System Works (And Why It Drains Batteries) Your car’s electrical system is a complex network of wires, fuses, relays, and modules that all rely on your battery and alternator. Here’s the basic flow: 🔋 Battery – Provides power to start the car and runs electronics when the engine is off. ⚡ Alternator – Recharges the battery while driving and powers systems ... read more

If you're a car enthusiast in O'Fallon, Missouri, or just someone who loves a little extra power under the hood, you've probably heard the terms turbocharger and supercharger. Both are forced induction systems designed to boost engine performance, but they work in very different ways. At Hillside Auto Repair, we see plenty of vehicles with these systems, and we know how to keep them running at peak performance. What Is a Turbocharger? A turbocharger uses exhaust gases to spin a turbine, which then forces more air into the engine’s combustion chamber. More air means more fuel can be burned, resulting in increased horsepower. Key Components:Turbine & Compressor Wheels – Spins from exhaust gases to compress intake air. Intercooler – Cools compressed air for better efficiency. Wastegate – Controls boost pressure to prevent en ... read more

Electric vehicles (EVs) are seen all over O’Fallon’s roads—from the school drop-off line to the commute to St. Louis. But one question keeps popping up: "How long will my EV battery actually last?" Unlike gas engines that wear out over time, EV batteries degrade slowly—but they don’t just die overnight. Let’s break down how they work, what wears them out, and how you can maximize your battery’s life so you’re not left stranded on I-64. And when your EV needs expert care, Hillside Auto Repair has you covered with dealership-grade tools, certified technicians, and a 3-year/36,000-mile warranty on all services. How Do EV Batteries Work (And Why Do They Degrade?) EV batteries are lithium-ion powerhouses, storing energy to propel your car without a drop of gasoline. Unlike your phone battery (which might quit after two years), EV batteries are built to last—most a ... read more

The Lowdown on Serpentine Belt Replacement If your car were a person, the serpentine belt would be the unsung hero keeping everything running smoothly—like a personal trainer for your engine. No, it’s not a fashion accessory (despite the name), but when it fails, your car will throw a fit. Let’s unravel the mystery of serpentine belts—what they do, why they matter, and when it’s time for a replacement. What Does a Serpentine Belt Actually Do? This single, snaking belt powers almost every critical accessory in your engine: Alternator (keeps the battery charged) Power steering pump (so you don’t turn like a truck driver) Air conditioning compressor (because Missouri summers are brutal) Water pump (prevents your engine from melting into a puddle) If it snaps? Say goodbye to power steering, AC, and eventually, your engi ... read more