Cooper1320

Got a noise coming from the engine bay passenger side. it is a rattling noise almost sound a pully bearing going out or like the fluid in the radiator expansion tank is boiling. Its a rattle or clanking type of noise this sound happens normally on cold starts after a few miles of driving it goes away.
Ive searched forms, googled & youtube'd but cant find the same problem I'm having. The sound does not speed up or get louder when driving and the sound happens in all gear including park and neutral. I've looked as best as i could trying to
track down the rattle sound but have not been able to find it. Ive had the car for about 8 mothing and this rattle has just recently started. the car is a 99 Integra ls sedan automatic transmission with no "Performance mods". the only thing i have done is remove the air silencer (because it was already cracked and braking) but I'm not sure if the sound happen immediately after doing so. the car does not smoke, not CELs, mpg hasn't been effected. All mounts are old but none of them are blown out or have failed completely. The sound could possibly be coming from the transmission. the car shift fine no banging into any gears or anything. i have already check the header heat shield and it is not cracked. Like stated the sound goes away after warming up and the sound can be heard from inside and outside the car. All fluid levels are good. I even bled the coolant system. exhaust hangers are good. cant think of what else else to try or look for.

Thank in advance for the input/help

Cooper1320

The sound appears to be coming from the transmission possibly, How would you be able to tell if the flexplate is broken or bad??

wunfstgsr

Try using a stethoscope and probe the transmission casing and see if the sound is coming from there. Those tools are pretty cheap.