QUOTE(HOUSECAT @ Apr 2 2008, 03:58 AM)
I know absolutely nothing about cars...but my moms car had the same exact problem and the Mechanic told us clicking sound is first sign your engine is about to blow up. Literally blow up so don't drive it. Until you get it fixed.
Think about it logically...
a clicking or tapping sound occurs when two hard part collide with each other.
and engine is designed so that no such collisions should occur, lots of things rub, but nothing collides
this mean that any clicking or tapping is caused by one of two things
1. a stuck component that due to build up in the engine doesn't move as smoothly as it should and separates from the near by components that it should have constant pressure on, like stuck lifters or valves
2. a warn out component that due to slack in the system (like a timing chain) is causing things to move out of sync with the rest of the system and causes components that normally avoid each other to start colliding (like a valve hitting the top of a piston)
Honestly.. the first thing you should do is any back maintenance... if the timing chain has never been replaced, start there and be sure to do it right... I'm not sure about your car but that might mean doing the water pump too.
Do a full flush of all fluids and if that doesn't work... well then you'll probably need a rebuild.
Engine's don't just "blow up" but when you start banging metal together at high speed heat and pressure you'll cause damage that can't be fixed without replacing the part, and you can't replace internal engine parts without tearing apart the engine, which is always expensive.
If it goes unchecked it's only going to get worse and will eventually reach a point where the collision is so forceful that something breaks and the engine will die completely. Sometimes it's a big enough collision to actually punch the broken part out of the engine right through the metal covers/block, other times the engine will lock up solid and it will be as if you slammed in your brakes.