Don’t ignore these engine noises
No matter how hard engineers work and assembly-line employees toil to perfect the engines in our rides, they make noise.
When they’re done right and the hood is closed, they emit a silky smooth hum and only growl politely — unless designed otherwise — through the exhaust when the pedal is punched.
If you think your engine might be suffering, keep reading — and listen for these hints and clues.
Heavy knocking on acceleration: Most crankshaft bearing failures start off with a deep and loud knock at the same speed as the crankshaft itself, while you’re accelerating. Leave a failing bearing to its own devices long enough, and the connecting rod to the piston will likely break, bringing you and your car to a grinding halt.
The number of shops doing major engine repairs, such as crankshaft and piston work, is decreasing. If you own a mainstream vehicle with a common four- or six-cylinder engine, don’t be shocked if your shop suggests a used or remanufactured assembly — assuming you’re out of warranty — instead of tearing down your engine and rebuilding it. Even some V8s aren’t worth repairing when compared to the cost of replacement. The best bet to avoid this is to keep to a solid oil-change regimen, get annual checkups, and don’t push the engine past its limits. Light ticking that goes away in a few seconds: This is often a sign of a hydraulic valve lifter that’s losing its oil charge overnight. These small but critical devices use engine oil under pressure to do their job, and they can develop small leaks. The noise comes from the fact they can’t keep up to the movement of the valves and camshafts until they’re recharged with oil — but this only takes a few seconds. Leaving them in this condition can lead to premature wear on other components, and of course, bigger repair bills.
Light ticking that goes away when the engine warms up: This is usually a sign of a leaking exhaust manifold, and often occurs only on larger engines with longer manifolds. While everything else under your hood has evolved, exhaust manifolds mostly remain dinosaurs made of cast iron.
Their constant heat-andcool cycles put stress on studs and bolts that secure them to the cylinder heads. When they first start to leak, they’re usually noisy only when cold; when the engine warms up, the manifold metal expands, sealing off the leak.
It won’t get better on its own, though, and will eventually develop into a leak large enough to spew out untreated emissions — possibly into the cabin, via the HVAC system. As well, exhaust leaks that reduce back pressure can cause head valves to overheat and sometimes fail.