I have a 89 240sx with 77,000 original miles on it. When I start up the car when its cold and been sitting awhile it makes a noise for about 30 seconds and then goes away. When i rev it at a certain rpm itll stay consistent and then go away. It never happens when im driving it or hesitates. It just makes that noise when the car has been sitting there awhile cold. Does anyone know what the noise could be coming from. Its sort of a light clinking noise, but its not coming from under the valve cover.

 

Is it your heat shield? Those always made the most noise during the winter seasons for me. I mean, I have no idea what to say to this since I can't hear the noise personally.

Good luck with getting any help from this.

 

Is it like a slight rod knock, If so it goes away when the oil warms up and fills up the gap, or is it like a rattling? Then I would agree with the headshield solution.

 

WAIT I CHANGE MY ANSWER!!! LOL

I was on the net and I came across this page:

http://garage.projectraine.com/

On the left side of the home page click on:
"My 240sx Garage Guides"

Then click on:
"Fix the Timing Chain Rattle"

What he shows how to fix, sounds ALOT like what you may be describing, either way its worth a look!!! Hope this helps!!!

 

12aine's site...

 

hmm could it be that???, the dohc are infamous for the chain guide tap, my sohc was fine with 200xxx miles on it. my dohc rattled at 72000 untill i took the guides out and stomped on them

 

But kids he's got an 89, and didn't mention a swap, so = SOHC. It happens on SOHC's too though FYI.

First of all, where is the noise coming from? do you know if it's actually coming from under the hood? Or under the car near the center? Narrow down the possibilities.