512DOGG

I have a 99 civic ex M/T and my car was running great till a couple days ago and im stumped on what it is. Car makes very loud hissing noise, sounds like a baby rattle with sand in it, starts @ 2k-5k gets so loud u can here it down the street while driving things i checked was, I thought mite be a clogged cat, o2 sensor loose,pcv valve unplugged, exhaust cracked or hole in it. car make noise rite under intake manifold. I do have a rear main seal leak but not sure if that could do it , any suggestion will be very help full. Would a intake manifold gasket leak be that loud? thankshttp://youtu.be/TyPtTkvR7sw

Galan

Check your hormanic Balancer...

512DOGG

added video link the hissing sound has got alot louder, just did timing belt,tensioner, fronk crank seal,ngk plugs,new plug wires cap& rotor,fuel filter

frankenghia

Kinda sound like a rocker arm. Hard to tell though without being there.... Did you double check and make sure your not off on the timing belt? Do you feel a lack of power at all? Does it run any differently than it did before all the repairs???

512DOGG

im going to double check my work this weekend, im pretty sure its not the rocker arm. even with the hood open and reving the motor i can hear it under the intake manifold, sounds like sand in a can

512DOGG

UPDATE: ok so i double checked the timing its spot on, but i got cell codes 45,67 system too lean,system too rich & catalyst system efficiency below threshold, my question is I checked the cat the front part and it looked good all honey combs no visual blockages im also getting flow from the tail pipe so could my cat still be bad or clogged?