weird sound from the timing chain

[persianboi]

hello all, I have a 1993 LE coupe.
I bought the car about a year ago and when I first bought it it would intermittently make a really weird noise. think of a muffled sound of a diesel engine, I have a hard time describing it but it would go away as soon as the RPM would go over 1000.
ever since about 3 months ago the noise has become constant but still does go away after the RPM goes over 1000.
I showed it to a mechanic and he told me that it might be a little plastic thing inside the engine bay that sits on top of the timing chains. he said he thinks that piece is broken and just rubbing on the chain. Im going to take the head off nd see what the hell is going on but I wanted to know if anyone else has had this experience and what it is if anyone knows.
I thought its probly time to do the timing chain since my cars at 150000 and i dont think its ever been done.
thanks.

[zachattack_5491]

Pretty much one of the most common problem in 240s. See that big red flashing SEARCH button? Learn it, use it, love it.

http://www.nicoclub.com/archives/fix-yo ... attle.html

[Biggins240sx]

Most Common noise. Remove valve cover. Unbolt upper timing chain guide, an/or remove broken pieces.