Rattling noise when hitting 4,000 rpms

[locdogg]

Hey guy's, I have a problem maybe someone can help me out.I have a 92 240sx with the stock ka24de engine. I have been hearing a rattling noise coming from the front of the engine when the engine gets to 4,000 rpms. I have taken off the top timing chain guides and still the noise remains. And before i get flamed, i have used the search button and found nothing on this issue. I am thinking it can be something in the lower timing chain but, i want to get an opinion before i start taking things apart. someones help would be greatly apreciated. thanks

[mksue3240sx]

Wow, two of these in one night. check the stretch on that cam chain. Once the upper guide is gone if that chain is stretched alot it can make noise.

[locdogg]

the noise was there even before i took off the top timing chain guides. and there was no sign of the top chain rubbing against anything when i took off the top cover.

[scooz14]

probably a bad tensioner on the lower chain. i had wicked rattling coming from my kae, not only were the guides bad, the the chain was really stretched.

[mksue3240sx]

Tensioner runs on oil pressure. Put an oil pressure gauge on your engine and check the pressure when the noise occurs. If your oil pressure is ok, probably time to pull your cover and redo the chains and guides tensioner etc...

[Colbys240]

that's good to know, I'm gonna have to hook up an oil pressure gauge

[locdogg]

I have an oil pressure gauge installed and when the noise occurs the gauge reads 60 psi. I'm more in the line of thinking it my lower timing chain guides are loose.

Tensioner runs on oil pressure. Put an oil pressure gauge on your engine and check the pressure when the noise occurs. If your oil pressure is ok, probably time to pull your cover and redo the chains and guides tensioner etc...

[airman86]

what kind of rattling noise? is it harmonic? (as in, same/close pitch as what the engine is vibrating)

the reason i ask, is sometimes heatsheilds/other things can vibrate if their harmonic frequency is close to what the engine is vibrating at. i had an eclipse that did it only at ~2.5k rpm, and it was an exhaust heatshield. took the heatshield off, no more buzzing/rattling.

[locdogg]

Thanks for the info. I had time today to pin point exact where the noise was coming from. While driving the rattling noise is coming from the front of the car. But when i open the hood and rev the engine to find out where the noise is coming from. the noise is coming from the transmission. and just this morning my transmission was making a whining noise at cold start when i pushed in the clutch. First thing came to mind was the pilot bearing.

what kind of rattling noisly where? is it harmonic? (as in, same/close pitch as what the engine is vibrating)

the reason i ask, is sometimes heatsheilds/other things can vibrate if their harmonic frequency is close to what the engine is vibrating at. i had an eclipse that did it only at ~2.5k rpm, and it was an exhaust heatshield. took the heatshield off, no more buzzing/rattling.