Strange engine sound?? Like a Marble bouncing around??

[Just a Six?]

I don't know exactly when this started?? Ray & I drove yesterday for an hour & can't say we heard it but it may still have been there? It only sounds really noticeable  at high idle. More RPM & it's still there but harder to hear? After the drive I changed my oil & I heard it while checking for leaks. It has great pressure as I just had it running at idle up to 1500 RPM for 30 mins. All I know for sure is I can pinpoint it to the lower of front cover area. Pretty sure it's not water pump but will run it with the belt off. Thinking maybe the double roller timing chain is slapping?? I don't know since I've never heard one before? I haven't been under the car yet but i doubt it's the balancer ring? Balancer looks to be running straight so I don't think it's loose but I'll check. Any other ideas?? 

[Forzfed]

Marble sounds like a bearing maybe?  I had a a loose timing chain that was hitting my cover, it sounded like a tick and would set off my knock detector, this was with the stock chain, don't know what a double roller would sound like.  Noise can resonate, that is a good idea to run it with out the belt and see if it goes away.

[Just a Six?]

Found it! Flywheel bolt is hitting! Glad it was something small! 

[Just a Six?]

Marble sounds like a bearing maybe?  I had a a loose timing chain that was hitting my cover, it sounded like a tick and would set off my knock detector, this was with the stock chain, don't know what a double roller would sound like.  Noise can resonate, that is a good idea to run it with out the belt and see if it goes away.

After the belt was off I stuck my head under the car & found it right away.
That trick works great! 

[Steve Wood]

what was it hitting?

[Just a Six?]

Actually Steve I was going to post this later. This AM I went under the car up on jackstands & checked everything & I can't pinpoint it exactly? On my way to have it put on a lift in 20 mins. The converter bolts are tight (which I thought it was) & I don't see any cracks in the flexplate but it's hard to have a good look laying on my back. I have a weird feeling it may be the converter?? It only happens above 1000 RPM but quiet in gear or low idle?
 Let you know what we find in a few hours. Also one oil pan bolt at the front of the pan is MIA??

[earlbrown]

is it the one on the passenger side that holds that PIA clip for the tranny lines?

If so, someone probably left it out on purpose.

[Just a Six?]

Earl I have flex lines but discovered a few things. On the hoist it's definately not flywheel or converter related. Now it sounds like something is rattling around under the tubo cover. Almost like a bolt that has come unscrewed & is hanging on by a thread & rattling against something metal or aluminum if that makes sense??
I'll take it apart in the next day or two. Also it seems that if I give it some throttle from 2K rpm - 3500 rpm while driving the noise doesn't increase at all & maybe even decreases? Altho its hard to say for sure with exhaust noise, road noise etc. It's dead quiet under 1K rpm?
I hope the turbo blade isn't chewed up or something like that. 

[Steve Wood]

it is almost impossible to see cracks between the flex plate bolt holes with the converter in the way and cracks there will make a similar sound.

Also, a bad converter can make a similar noise so unbolt the converter and push it back a little before starting the engine to see if you still have the noise

[Just a Six?]

I forgot about that trick. IOU a  Cold     
The converter I put back in last spring (as well as using it 5+ years ago) is a used 911 I got from Norbs about 10 years ago. Brad said in a post 1-2 years ago that some trash went thu it when Norbs grenaded his tranny. I found it a bit slow to spool for a 3400 LU but that's the only complaint I've ever had with it. There was no noise when I parked it for winter
But maybe the Norbs Curse is after me!!        

[Steve Wood]

It is very hard to see if there are any cranks between the bolt holes due to the small distance the converter will move back...if it is bad, sometimes you can grab the ringgear and push/pull the flex plate back and forth and see the cracks if you have a bright enuf light shined at the ring gear bolts

[Just a Six?]

CRAP!! I just typed up everything & it was deleted when I tried to add some pics with this new camera because it says they are too big? That's an issue for another day!
Anyways turbo is in great shape but had an exhaust leak between top 2 bolts to RJC downpipe. Puck ring is perfect. Cleaned it all up then a smear of silicone & that leak is all good now.
Just below turbo on front cover (where noise seems to be lately) the Precision Stock location intercooler has an aluminum mounting plate. The top bolt was quite loose & I think the washer was humming at higher RPM.
I snugged it up about 3 turns but there is still a noise that is a mystery? I only ran it 30 secs.
It does sound better without the leak but a definate noise.
Tomorrow I'll check the crank bolt for 200+ lbs torque then undo the converter & slide it back.
I will find it eventually but for now I'm still hunting.
In a way this is good as I have been losing interest in the car all winter but this has my curiousity peaked & in a strange way is probably good for me to get back at my hobby!
Altho, I wouln't complain if I could find the answer sooner than later! 

[Just a Six?]

INCREDIBLE!!! It was the Crank Sensor!! I tugged on it pretty hard after looking at the balancer etc & it moved just enuf that the higher RPM would make it vibrate againt the 3 rings. I set it with my trusty credit card trick & boom noise is gone!
Along with the Precision intercooler rattling & the exhaust leak I went thru every nut & bolt I could access and it's much quieter now. There was even a little rattle from the shroud hitting my oversize front swaybar that was in the mix at some RPM. Drained the rad for fresh water & RMI while I was under the car & dirty anyways.
I'm still Amazed how the sound traveled & seemed like it was above at turbo & behind the balancer at flywheel. The crank sensor was one of the fisrt things I checked but I never yanked on it hard enuf to see if it had movement.
Lesson learned!! 
On the bright side the car is quieter & amazingly my back is still holding up ok. 
The Flexeril help chased with a couple beers! 

[Steve Wood]

Good!