You turn the key on a cold morning and there it is, that unsettling knocking sound from under the hood. But here's the weird part, after a few minutes of driving, it just disappears. What's going on? Cold engine knocking usually comes down to oil viscosity and clearances between moving parts. When your engine sits overnight, oil drains into the pan and thickens. During those first few minutes, that thick oil doesn't flow properly through tight spaces, causing metal-on-metal contact you hear as knocking. Once everything warms up, the oil thins out and flows normally again. If you're hearing this regularly, your engine might need attention from an Engine Rebuilding Service Edgewater FL before minor wear becomes major damage. Sometimes it's just worn bearings or piston slap that gets quieter as parts expand with heat. CHS Machine Shop : https://www.google.com/maps?cid=10045883614448735154 Find out more : https://vintfint.com/blogs/222986/Why-Your-Engine-Knocks-When-Cold-But-Stops-When-Warm