What is Engine Knocking?

April 12th, 2013 by

Lovering Mitsubishi ServiceYou’re sitting, idling at a red light. Rather than the smooth, gentle purr your car used to make when you first got it, you hear this rough banging sound emanating from under the hood. It also probably feels like you’re sitting on an intermittent rumble seat.

There isn’t too creative of a name for what’s going on; it’s called knocking. It can happen for a number of reasons, but they typically all lead to the same result. Part of your fuel ignites when it’s not supposed to, jostling your cylinders. Clearly this is not ideal and can be fairly expensive for your mechanic to fix. First let’s talk about what exactly is going on inside your engine and where the knocking occurs.

Knocking: A Sure Way to Big Engine Problems

Most people understand the basic principle of how an engine works. Atomized fuel is injected into an engine cylinder and mixed with air. This air/gasoline mixture is at the perfect ratio to create proper combustion. As the piston in the cylinder rises, it creates greater pressure and thus greater heat.

Though the increased temperature creates a good environment for the fuel to combust, it’s not enough to ignite the mixture. This is where your spark plugs come in. As the piston reaches the top of the cylinder, the spark plug is timed to ignite the mixture. Combustion begins around the tip of the spark plug and quickly expands outward in a dome like fashion.

Not that we’ve gotten engine basics out of the way, here’s when knocking can happen. All the fuel doesn’t get ignited right away, so as the piston continues to rise, the increasing pressure causes the rest of the fuel mixture to combust. This creates a second reaction, also known as a “detonation.” This can happen for a number of reasons:

  • Bad spark plugs or the wrong spark plugs.
  • Build-up in your cylinders that create excess pressure.
  • Low quality fuel.

Letting this go can lead to cracks in the pistons and cylinders, meaning expensive repairs or total engine loss.

Lovering Mitsubishi Can Help

Like we said, ignoring engine knocking can lead to expensive vehicle repair problems. Taking care of it sooner than later is the best plan of action and our team is certainly happy to help. We offer fast, efficient service for competitive prices.

Lovering Mitsubishi is located at 93 Manchester Street, in Concord, a short drive from many towns in the central New Hampshire area. We service most vehicle makes, not just Mitsubishis. To make an appointment with our team, feel free to give us a call or use our online scheduler!

Posted in Mitsubishi Service