O'Fallon Auto Repair

Your engine is a symphony of controlled explosions—but when the timing is off, it can sound more like a chaotic drum solo. Pre-detonation (engine knock) is one of the most destructive issues an engine can face, and if left unchecked, it can lead to costly repairs. What Is Pre-Detonation? Pre-detonation (also called engine knock or spark knock) occurs when the air-fuel mixture in the combustion chamber ignites too early—before the spark plug fires. Normally, combustion happens in a controlled burn, but pre-detonation creates multiple flame fronts, leading to violent pressure spikes that hammer your engine’s internals. Think of it like trying to push a swing at the wrong time—instead of smooth motion, you get a jarring clash of forces.   What Causes Pre-Detonation? Several factors can trigger knock, including: 1. Low-Octane Fuel Using regular (87 octane) gas in a high-compression ... read more

Imagine your car’s engine is like a human body—and oil is its blood. Now, picture driving with a massive oil leak like trying to run a marathon with a slit wrist. Sure, you might make it a few more steps, but eventually, you’re going to collapse. Recently, a customer called us wanting to drive her car in despite it hemorrhaging oil. She figured, "It’s still running, so how bad could it be?" The answer? Catastrophic engine failure bad. In this post, we’ll break down: ✔ Why oil is your engine’s lifeline (it’s not just about lubrication) ✔ What happens when you run out of oil (spoiler: it’s expensive) ✔ Why you should NEVER drive with a severe leak (tow it instead!) ✔ The risks of DIY oil leak repairs (and why pros do it better)   Oil Is Your Engine’s Lifeblood—Here’s Why Oil isn’t just there to keep parts sl ... read more

If you drive a manual transmission, your clutch is one of the most critical components in your vehicle. But even if you’re an automatic driver (don’t worry, we won’t judge), understanding how clutches function can help you recognize problems before they leave you stranded. Let’s dive into what clutches do, how they work, when they need replacing, and why you should always trust a professional for the job.   What Does a Clutch Do? The clutch is the middleman between your engine and transmission. Its job? To smoothly engage and disengage power from the engine to the wheels, allowing you to shift gears without grinding metal or stalling. Without a clutch, every gear change would be a violent, teeth-gritting experience—no thanks!   How Does a Clutch Work? A clutch consists of several key parts: Flywheel – Attached to the engine, it spins with it. Clutch Disc – Sandwiched between the flywheel and p ... read more

Your car’s engine oil is like its lifeblood—without it, your engine would seize up, overheat, and fail catastrophically. Yet, despite its critical role, many drivers still wonder: How often should I really change my oil? The answer isn’t as simple as the old "every 3,000 miles" rule. Modern engines and advanced synthetic oils have changed the game. Let’s break it all down. The Vital Functions of Engine Oil Engine oil isn’t just there to keep things slippery—it performs several crucial jobs: Lubrication: Reduces friction between moving parts, preventing wear and tear. Cooling: Helps dissipate heat from the combustion process. Cleaning: Carries away dirt, metal particles, and sludge. Sealing: Helps piston rings maintain compression. Corrosion Protection: Coats components to prevent rust and oxidation ... read more

There’s a unique kind of panic that strikes when your car suddenly refuses to move in traffic—and it often starts with a dying clutch. Whether you're driving a spirited manual coupe or a trusty workhorse pickup, your clutch plays a crucial role in how power from the engine reaches the wheels. Like any other wear-and-tear part, the clutch doesn’t last forever. But how do you know it’s on its way out before it strands you at the worst possible time? At Hillside Auto Repair, we believe in keeping you one step ahead of unexpected breakdowns. Our experienced technicians work with dealership-grade tools and diagnostics to provide top-tier repairs and maintenance, including comprehensive clutch service. Let’s break down the tell-tale signs your clutch is waving the white flag—and what you should do next. 1. Slipping Gears While Accelerating If you're accelerating and notice the engine revs but the car doesn’t gain speed as e ... read more