What could cause an engine to 'tick'?

The "tick" of the engine is caused by the pre-ignition in the chamber before it reaches the spark plug. Because the gas is combusting before it reaches the spark plugs, this is causing the "tick" noise. Recommend using a higher grade of fuel "mid-grade" Have you checked your oil lately? If not check it and if it is low add more and the ticking should go away. are you sure you are not hearing the normal noise of the fuel injectos doing their job? a properly-working fuel injector will make a clicking noise. Some times you can hear it while driving in a quiet place, or when the engine is running and you are under the hood. THAT is a normal sound. http://www.autozone.com/servlet/UiBroker?UseCase=S001&UserAction=viewSimpleDiagInfo&Parameters=info answer not pre-ignition. ticking sound is more likely to be a small exhaust manifold leak. or a sticky hydraulic lifter, an engine flush and oil change will fix it ANSWER FROM DAN

the ticking noise may be your lifters if you put new oil in and the ticking does not go away try tightening your lifters. you may want to take the car to a garage because you could wreck more than help if you over tighten. or don't fit gasket correctly.