Loud engine noise at around 3k rpm...

[SilviaSR20DET]

YA i notice this loud noise coming from my engine and im wondering what that might be. So far the only thing that broke since i got my car was the AC condensor pipe (low pressure) and im not sure if that is the thing thats causing this noise. Its very noticeable everytime i rev my car from 3k to 3500 rpm (Its sounds like a really loud rattle inside the engine). I removed my heatshields from the header thinking that it will get rid of that sound but it didnt. Any help will be much appreciated, thanks.

[SilviaSR20DET]

oh yea by the way its a 96 240sx 5 sp

[JustinHallenbeck]

Does it sound like marbles in a can? :X

[CustomS14A]

:boink: "mabye" "exhaust" "gas"

[Hawd]

Did you try removing the heatshields on the second dummy cat? It would be on the driverside

[idlafie]

You check the bolts on your heat shield by the front cat? It's behind the front driver fender well right by the firewall. One of the bolt heads could have snapped causing your heat shield plate for the cat to vibrate. It's a thought...
Hope this helps...
ID

[aznpoopy]

most likely timing chain rattle. do a search for 'timing chain rattle'... look for a post by misnomer in the FAQ section. if you open up the hood and let someone rev it it should sound like its coming from the front right under the valve cover, right?

[SilviaSR20DET]

YA it is in the front of the valve cover i beleive so how would you fix the timing chain rattle? Do i have to buy a new timing chain? When i put my hand on the valve cover it vibrates alot so it maybe the timing chain

[ZenkiS14]

Open your valve cover and see how loose the chain is.. I just bought a 92 that I'm gonna rebuild for my chick, and the very top metal plate was completely broken off....

[mrmephistopheles]

if it's at the front of the valve cover, it's likely to be the upper timing chain guide. more often than not, they're the biggest cause of timing chain rattle. pull your valve cover and pull off that guide.. sometimes it breaks off and bounces around on the chain.. wooo not safe.

[SilviaSR20DET]

If you remove the upper chain guide will it be safe?

[aznpoopy]

why didn't you check out the information i referred you to? that would've answered all your questions.

there are two upper timing chain guides. the problem is they get loose or come off their mounting screws or whatever and they SIT on your timing chain as it turns, slowly grinding little metal bits into your engine. when you take your valve cover off to remove these, you should note 2 things. #1 have they gotten loose or are they still tight? #2 how is the slack on your chain? if they are loose and sitting on the chain u figured out your problem. take them out and that's it. if they are tight and the chain is hitting it then you can take it off now for a quick fix but you will need to fix your slack timing chain.

in other words, the answer to your question depends on what the problem really is.

a) loose chain guide -> removal of chain guides -> problem gone.

b) loose timing chain -> removal of chain guides-> timing chain will eventually start tapping against your valve cover (bad)

assuming your case is (a), then yes its perfectly safe; there is even a nissan technical bulletin about it. read about it in FAQ section by misnomer!

[SilviaSR20DET]

Hey thanks for the help it really made it alot more clearer for me.