What Does “Throwing a Rod” Mean, and What Causes It?

The inner workings of cars are mysteries to many people—men and women alike. Technicians often use terms like “throwing a rod” to explain engine failure, and while car owners may nod in agreement, they may not have any idea what that means. Let us explain…

Definition: Throwing a Rod

A combustion engine is a complex machine with pistons that move up, allowing air and fuel into the piston chamber, and then move down to compress both, creating a controlled explosion that powers your car. The energy from that explosion turns a rod that connects the piston to a crankshaft, which transfers energy into forward motion. The connecting rod is the component at issue in the phrase “throwing a rod,” a term used to describe a broken rod that compromises your engine’s performance.

What Causes a Thrown Rod?

The most common contributors to a thrown rod include:

  • Loosely attached bolts that do not securely hold the rod in place

Symptoms include a metallic noises (clanking) from your engine (admittedly, they may be hard to hear over regular engine noise…and the stereo)

  • Overheating/poor lubrication, which increases the friction between the rod, piston and crankshaft

Increased heat and friction weaken the metal rod, making breaking more likely

  • Broken intake or exhaust valve that disintegrates into the engine piston

A big enough piece can interfere with normal piston/rod/crankshaft movement. While the rod may be the component most likely to give, it may not be the only component damaged—the piston head may be affected, too.

Many of the causes of thrown rod can be prevented with routine maintenance and careful inspection. If you’re not sure if your engine is heading for disaster or not, bring your car to Quanz Auto Body just to be on the safe side.