Under Hood Clicking noise

[BIGJB27]

I have a 2001 Explorer sport and there is a clicking coming from under the plastic cover on my engine. Any ideas what this could be. It started several months ago and has gotten worse within the past couple of weeks. I haven't noticed any performance problems but it sounds awful. Thanks guys.

 

[TPLYNCH]

Is it a constant sound, like every second, or is it delayed (like your a/c compressor turning on) for 5-10 seconds?

 

[BIGJB27]

It is continuous. As soon as I start it up. It gets faster when I accelerate.

 

[BIGJB27]

I checked all of my plugs and they all seem to be firing correctly. Could this just be a carbon problem. I use 87 octane all of the time. If I use 92 octane I have problems with it stalling. Anyone else run into this problem?

 

[TPLYNCH]

Check for leaks in your vacuum and EGR lines. Also, if you have the SOHC engine, it could be the timing chain cassette or camshaft tensioners crapping out on you......