Did you ever find out if this was fixed via replacing the timing belt tensioner? I have a similar issue on mine, I've replaced the belt but still get a noise from it (though not quite as bad). But mine used to make the same noise as yours when I would start it up.

 

That is so funny how you asked this right now. The noise kept getting worse and worse so i decided to re do the timing belt just today!

I got everything undone and put new tensioner on and everything.
The new tensioner was bad so i had to take it all back a part.

Check your tensioner this seems to be a common issue.
I will try and write back tomorrow evening when i replace the tensioner with another new one.

 

I had to take back the tensioner that came in the timing kit so i haven't had a chance to fix the tensioner and see if thats it 100%. I will fix it tonight and get back to you.

here is a symptoms tree that i got from my shopkey. Its where I am going next if the tensioner did not fix the noise.

I know yours may not be the 2002 like mine but if it has the 3.5 it should pretty much be the same.

I am however almost positive its the tensioner in my case.

 

Mine was in fact a defaulty timing belt tensioner so i bought the kit and re did the whole timing again.

 

From my experience when the hydraulic tensioners go bad they tap constantly, cold, hot, on fire... All the time. Do not buy the Chinese made replacements, buy only the German or American made ones. The cheaper ones don't last longer than 20,000 miles.