Originally Posted by Opiate
don't know if it's the same thing or not, but I have a '97 Civic and mine always knocks in the winter time while warming up. After it's been running for 2 or 3 minutes the knock goes completely away and it's quiet again. It's done that for the last 4 or 5 years.
What is happening with yours is called piston slap. Pistons are slightly smaller then the cylinder they are in . This allows them to expand when they heat up.They are also not perfectly round but are cam ground(i think that is the term) This also allows for expansion when they get warm. That is why the sound goes away when the engine heats up.