O'Fallon Auto Repair

As temperatures rise, your car’s cooling system faces its toughest challenge—preventing overheating under the scorching summer sun. Many drivers assume that water is enough to keep their engine cool, but the truth is far more complex. Using plain water instead of proper coolant (antifreeze) can lead to costly repairs, reduced engine life, and even sudden breakdowns. At Hillside Auto Repair, we’ve seen firsthand how neglecting cooling system maintenance can turn a summer road trip into a roadside disaster. In this guide, we’ll break down why coolant is superior to water, how your cooling system works in extreme heat, and the warning signs that your vehicle needs immediate attention. Why Water Alone Isn’t Enough for Your Engine Water might seem like a simple, cost-effective coolant, but it has major drawbacks: Water Boils Too Easily - Engines operate at 190–220°F, and in summer, under-hood temps can soar eve ... read more

When it comes to your vehicle’s drivetrain, few components are as crucial—and as misunderstood—as the differential. Whether you're a car enthusiast or just a conscientious driver, understanding how your differential works, how to maintain it, and what warning signs to look for can save you from costly repairs down the road. At Hillside Auto Repair, we specialize in diagnosing and servicing differentials to keep your vehicle running smoothly. Plus, with our nationwide 3-year/36,000-mile warranty on parts and labor, you can trust that your repair is built to last. What Is a Differential and What Does It Do? The differential is a gearbox located between the drive wheels (or axles, in 4WD/AWD vehicles) that allows the wheels to rotate at different speeds while delivering power from the engine. This is especially important when turning—since the outside wheel must travel farther than the inside wheel, the differential ensures smooth handling ... read more

When the summer heat hits, there’s nothing worse than turning on your car’s air conditioning only to be greeted by warm, stale air. Your vehicle’s A/C system is a complex network of components working together to keep you cool—but how does it actually work? In this guide, we’ll break down the key parts of your car’s A/C system, explain their roles, and highlight what can go wrong. And if you’re experiencing A/C troubles, Hillside Auto Repair has you covered—we offer expert diagnostics, top-notch maintenance, and a nationwide 3-year/36,000-mile warranty on parts and labor for all services we provide. The A/C Compressor: The Heart of the System Function: The compressor is essentially the "pump" of your A/C system. It pressurizes the refrigerant (usually R-134a or the newer R-1234yf) and circulates it through the system. How It Can Fail: Leaking seals can cause refrigerant loss. Electrical f ... read more

Your engine is a symphony of moving parts—but if the camshaft caps fail, it’ll sound more like a death metal band. These unassuming little components are the unsung heroes (or villains) of your valvetrain, and when they crack, your engine’s performance—and your wallet—pay the price. Let’s break down what camshaft caps do, why they self-destruct, and how to keep yours alive before they take your engine down with them. What Are Camshaft Caps? (And Why Should You Care?) Camshaft caps (a.k.a. cam bearing caps) are the metal brackets that hold your camshaft in place inside the engine block. Think of them as the bouncers at a club—they keep the camshaft aligned and spinning smoothly so your valves open and close at the right time. No camshaft caps? No valve timing. No valve timing? No combustion. No combustion? Well, you get the idea. These caps are bolted down over the camshaft bearings, ensuring everything stays where it sho ... read more

If your car’s air conditioning isn’t blowing as cold as it used to, one of the first culprits that comes to mind is low refrigerant. But here’s the thing—your car’s AC system is a sealed, closed-loop system, meaning refrigerant isn’t something that just *disappears* over time like engine oil or windshield washer fluid. So, if your refrigerant level is low… you almost certainly have a leak. Why Can’t You Just “Top Off” the Refrigerant? You might see DIY refrigerant recharge kits at auto parts stores and think, “Why not just add more and call it a day?” Here’s the problem: - Refrigerant doesn’t get “used up”—it circulates indefinitely in a properly functioning system. - Adding more without fixing the leak is like pouring water into a bucket with a hole—it’ll just leak out again. - Overcharging the system can cause damage to the compressor, leading t ... read more