my car makes a chain noise at 3000rpm and only at 3000rpm can someone help me

[green240sx]

Yo. i just bought a 240sx coupe 93. My problem is that my car makes noise at 3000rpm a chain noise. it only makes that sound at that rpm. i have a friend who has the same problem and was fix by changing his transmition fluid so i am asking if thats the problem or do i need to change my time belt?

[i2ice4m3]

if your car is stock engine you don't have a timing belt. You have a timing CHAIN and that might be what's making that noise. If you search around for chain/rattling noises you will find a common problem with 240s is the timing chain guides wear or break. If that is the case, which I believe it is, you need to pop off your timing chain cover and replace the chain and related parts. They sell kits for this, but for the DOHC i've heard it's a pita. good luck man and the SEARCH button is your friend. Located at the top right corner, in red. flashing.

[nuts510]

if your chains making the noise you need to replace it along with guidance there's a couple of service bulletins you need to check and I'm not trying to scare you but the shop I work at we charge almost 15 hours for this job it's a bit of a challenge I would almost recommend somebody trying this at their house to just pull the motor it would abuse you much less and also get it out so you can get to everything easily.if the chain goes it will destroy your motor I have actually poured the valves out of the exhaust system after this is happened