Noise from under the valve cover

[David Aamidor]

I have 93 DOHC 240sx.  At idle you can hear and feel a knocking from inside the valve cover.  I am not sure what it is because when i took off the cover there were no real obivious signs of wear.  However i suspect it may be a bad upper tensioner.  However it might be a warped cam or a bad lifter or bearing.  How could i confirm what my problem is?  What signs should i look for in the tensioner to see if it is what is wrong and also what should i look for in the valve train.
Thanks

[silviase]

hey david listen to this bing,bong,bang that the sound of ignorance. there is'nt a mechanic that can tell you what is
wrong with it unless they actually hear the noise. and it takes
a trained seasoned mechanic to do that. I don't think you going to get an educated answer to that question unless some
can actually hear the noise.

[sykikchimp]

just remove the upper chain guide (on the upper chain). It is the L-bracket you see sitting directly over the chain when you take off the valve cover. it has no real purpose anymore. Nissan has removed it from their parts list completely. If you still have the noise after that, it may be the also now obsolete lower chain guide (on the upper chain). This one is quite a bit harder to get to. From the questions you've been asking it doesn't sound like your ready to tackle anything more than the top guide. I would recommend having a mechanic check it out asap if removing the top guide doesn't help.

remember the KA is an interference type engine which means if the chain Does break.. your valves are screwed

[S13Grl]

It's most probably your timing chain, as you've already figured.

However, are you sure that there are no knocks in your comb. chamber? You may be confusing the two sounds. Timing chain rattle is quite obvious, you'd know that it's the chain by hearing it.