I've looked through other posts but I have not found a similar problem.
MY01 has 169,xxx miles. Just swapped out the third trans with 60,xxx miles last weekend. Original trans made a similar grinding noise but was only audible from 2500rpm-3000rpm while in neutral, clutch in and in or out of gear, and accel and decel.
I replaced the trans (66k mi on it) and clutch (aftermarket) along with the pilot bearing, PP, resurfaced the flywheel, torqued all bolts to spec. The noise still was only audible as described above.
1000 mi later the noise worsened after I opened it up on an on ramp and came to a stop. The guy I bought the trans from sent me another. I installed it last weekend and still the noise exists as you can hear in the video. Replaced trans fluid, engine oil, and diff oil when I got it.

Valves have been adjusted and I don't know if the TCT has been changed or even the timing chain for that matter. I took it to a local shop and they wanted to pull everything apart but I don't have the money to pay for all that labor. They pulled plugs and took the load off of each cylinder but the sound still persisted. They suggested a wrist pin making noise but I don't know. I have access to a shop, lift and tools; plus I'm mechanically inclined and have done my fair share of auto work. This has me stumped!
I'd appreciate any suggestions.
Thanks

http://s1371.photobucket.com/user/os...7627b.mp4.html

 

Check the header support bracket at the lower end of the header. Sounds like something is cracked.

 

Billman250 thanks for the response! I remember that bracket bolt missing after the first transmission swap... I'll replace the missing bolt tomorrow and let you know. Also I forgot to write in the first post that there is a vibration that can be felt in the clutch pedal and shifter when the car is idle (subtle and never existed) and virbration can be felt coming from the intake manifold when the engine is revved.

 

As my luck would have it, Honda does not have the bolt and washer in stock and won't until Monday December 2! Guess I'll have to try not to let it bug me all weekend long. Happy Thanksgiving everyone.

 

Billman250,

So I replaced that missing bolt with the correct washer and the noise still exists. The sound can be best heard from the passenger side of the car with ones ear to the cylinder head nearest the firewall..
http://s1371.photobucket.com/user/os...?sort=3&page=1

Many thanks,
Orlando

 

Ask yourself, why was that bolt missing? Someone was in there messing with things at some point. So maybe there is something else there that isn't right besides just the missing bolt.

Get under there and have another look around. Try getting the car in the air and see if you can have someone recreate noise while you are under (careful!). Probe around to see just where its coming from, and see what is lose.

 

Thanks for the reply,

I've been the only one working on the car since I bought it. I replaced the trans twice because the OE trans was bad and this noise started about 1000mi after I installed the used trans. I got another replacement trans under warranty and installed the current one. sound still persist.

I had an auto shop put it in the air and listen with a sound probe but they insist on tearing it apart to find the noise but I don't want to pay the labor for that. The ran it and pulled one coil plug at a time to see if the sound would stop but it didn't.

I know I torqued down all the bolts connecting the flywheel, pressure plate, and all the bolts for the transmission to spec. The flange bolt that was missing is the only one I missed. I'm going to pull the valve cover off this weekend to see what I can find because the sound is prominent in the head above cylinder 4. I'll post what I find.

 

Uninstalled the valve cover and the only thing I found was the coil gasket o-rings are bad and plug #1, 2, and 3 plugs have oil inside the area where the plugs screw in. the car idles fine and runs well otherwise but those will definitely get replaced.
I was thinking about unplugging one coil plug at a time to see if the sound goes away. After digging around in there I don't believe the shop I took it too last week pulled the plugs like they said they did.
Any solutions or ideas would be most helpful!

 

After much deliberation and taking as much apart as possible I've come to conclusion that I'll have to take the head off and further inspect the whole engine. Since I'll have everything apart I'm going to be rebuilding the block with 87.5mm CP pistons, 98mm crank and ACL race bearings. Looking to run 11:5:1 cr.
Peace.

 

so you've decided to rebuild the entire motor to alleviate a noise that you cant even pinpoint?