Engine Problems Explained: Detonation Or Engine Knock

Modern engines offer a perfect mix of smoothness, tractability, performance, and efficiency.  Is your vehicle exhibiting strange noises from under the hood, feels underpowered or runs rough? It may be suffering from engine knock.

In this blog, we discuss detonation or engine knock, what it can do to your engine, and what can be done to resolve it.

What is Engine Knock?

The terms engine knock and detonation are used interchangeably. But in essence, detonation (also called pre-detonation) causes engine knock. Detonation is caused by early combustion in the cylinders.

What Causes Unwanted Detonation?

In a gas engine, the pistons undergo four distinct strokes: intake, compression, power, and exhaust. This process is completed thousands of times a minute. When detonation occurs, the fuel/air mixture is ignited early, before the piston has risen to the correct position. This means that the explosion of fuel is trying to push the piston the wrong way. Power from other pistons keeps the engine running. But the power stroke won’t make full power, and the engine starts to run rough.

Causes of unwanted detonation:

• Engine running too lean
• Compression levels too high
• Carbon build-up – carbon particles can ignite
• Exhaust system clogged up
• Ignition timing is too advanced
• Poor fuel
• Cooling system issues – overheating engine can pre-detonate

In the video below, we discuss the causes of detonation and show what happened to a small block Ford Windsor motor with a bad engine knock.

What Kind of Damage Can Detonation Cause?

To see just how much damage unwanted detonation can cause in an engine, take a look at this video below, which shows the damaged pistons and block of a GM L92 6.2-liter V8. In this case, it damaged the pistons, rings, and bearings.

Knock sensors are used in most modern engines to pull back the timing and hopefully prevent detonation. But some engine damage can still occur. This will not resolve the cause of the detonation problem. Potential issues caused by detonation:

• Bent pushrods
• Scored and worn pistons
• Damaged rings
• Damaged bearings

How Do We Address Detonation Issues?

Driving with an engine knock will result in a failed engine. If your vehicle is fitted with knock sensors, the damage from detonation can be minimized. But the cause of the engine knock will still be there. If you notice a reduction in power, increased fuel consumption, and general rough running, have your engine inspected.

At PPI we take a holistic approach to engine detonation issues. We strip the engine to assess the damage and replace any components that are damaged or faulty. We also rectify any known manufacturing issues, some of which may have been the cause of the detonation in the first place.

Choose Powertrain Products For Quality Remanufactured Engines

Whether your engine knock means you need a replacement motor or just a rebuild, Powertrain Products is ready to help. We stock over 3000 rebuilt and used engines.

All our remanufactured engines are fully assembled and updated to correct any factory faults. We offer a 3-year standard warranty on all of our engines. That standard warranty can be upgraded to 5 or 7 years or 1 million miles, whichever comes first.

For the ultimate protection – purchase our no-fault Pure Care™ Warranty. Need a few more parts for your vehicle? We’re also the nation’s leading supplier of differentials, transmissions, and transfer cases.

Call us at 888-842-0023 or contact us online. Our friendly staff will help you find the perfect replacement part in no time.