Bang! Bang! Bang! Bang! Bang!

[lovehamr]

That's the sound that my 462" FE started making on my way home yesterday.  It started softly enough that I really couldn't hear it over the exhaust but it got gradually louder until I could also feel it in the floor and steering wheel.  The car is a fake Cobra with solid mounts so everything tends to get transmitted to the driver.  Once a realized that I wasn't hearing a blown header gasket or something like that I shut her down, coasted to a stop, had it started once with me outside the car to hear it for about 10 seconds the trailered her home with a huge pit in my stomach.  During this, I never lost any oil pressure, there was no overheating or anything like that.  Just the bang bang bang noise, it wasn't even missing or running weird.  So today I pulled the VCs thinking I had a rocker failure or something but nothing up top seems amiss.  So I pulled the Aviad RR pan which is a huge PITA and started pulling rod caps and checking the bearings.  The engine has just over 7k miles on it and you can tell that it's been run by looking at the bearings but there really aren't any problems there.  It’s certainly not enough to explain the horrid noise coming from the thing.  I took pics of all the rod cap bearings and journals and am posting a link to them on my photobucket page.

http://s266.photobucket.com/user/lovehamr/library/Noisy%20FE

All of the other surfaces that I can see all look almost brand new, i.e. the bottoms of the pistons are all perfect with no discoloration at all, the cam lobes and lifters all look great as well.  I'm turning the crank by hand to do all this and haven't felt any rough spots or heard any noise during the 1 revolution that I turned it. 

So, WTH guys?  Ya'll have any ideas before I hook up a starter switch and turn this thing over with me under to hear/see what's going on?

Thanks, Steve

[My427stang]

Are you sure its inside and not clutch or flywheel?

[cjshaker]

If you can't find any excess play or witness marks anywhere inside the engine, then like Ross said, start checking on either side. Check the clutch and flywheel veeeery carefully. Also, if you have a mechanical fuel pump, they can get real noisy, like rod knock noisy, if the pump arm spring is loose or busted. Maybe check the damper also as I've seen them start to come apart before.

[lovehamr]

Thanks for the suggestions guys.  With my hearing it very well could be in the clutch/flywheel.  No mech fuel pump to worry about though.  Guess I'll be yanking the trans today.

[cammerfe]

Wish you well! Had an intermittent noise such as you reference and ultimately found a small chunk of loose aluminum flash occasionally making contact with the converter. This was in a car with 20 K miles before anything was audible.

KS

[ScotiaFE]

I'd have been getting out the stethoscope and doing some probing.

[lovehamr]

OK got the drive train out and found no obvious problem.  One thing that stands out is the flywheel was loose on the crank after all the bolts were loosened.  I've installed and removed this Fidanza aluminum FW 3 times now and, up until now, getting it on or off has been quite an exercise.  Not today though as it practically fell off.  There are no obvious cracks that I can see but the way it fits the FW just isn't right.  Never had a broken FW, could this be it?

Scotia, with my hearing I'm a big user of a mechanic's stethoscope but the way this thing was banging it sounded like something catastrophic was going to happen any second so I shut it down.

[Woods]

I have been down this road, before I start pulling the engine (that's what I did the first time) I check my distributor cap for cross tracks.  Now I always carry a spare cap for those road trips.  No guarantee but worth a look.

[My427stang]

If it fit tight and now its loose, something changed.

Look close at the rear main cap and block, make sure your flywheel bolts weren't hitting.  Some bottom out lightly and you could have been pushing the crank back with the bolts and still had the flywheel only marginally tight.

If you do find they were hitting, I would replace the mains, actually only the thrust bearing if it is eaten up, and I would have the flywheel zyglo'd to check for cracks.  However, if there was no damage to the crank thrust area and the flywheel wasn't significantly damaged, I'd trim a set of bolts and run it

[lovehamr]

OK, finally had the time and motivation to get back out there and look at things closer.  First up I checked the dist cap and other than a worn center electrode I see no evidence of carbon tracking or anything else that would cause this problem.  That checks with me because it was running fine while it was making that noise.  Here's a pic of the cap:



Now the flywheel.  Having never cracked one before I wasn't sure what I was looking for so I took it outside and cleaned it.  Low and behold what did I find, but a crack that would at least explain why it's loose in the crank all of the sudden.  However the crack doesn't seem to all the way out the FW, it looks like it's only at the crank/bolt area.  For you guys who've seen this, does it look like this could be my noise problem?  Here are a couple of pics:

[jayb]

Don't know if that's the noise problem or not, but for SURE you need a new flywheel, Steve.  And if that crack was causing the flywheel to flex who knows what could be happening.  I had a pressure plate once where the bolts holding it to the flywheel were coming loose, and the bolts on the back of the pressure plate that held the release levers in place started hitting on the inside of the bellhousing.  Made a godawful racket.  You don't by chance see any witness marks inside the bellhousing do you?

[lovehamr]

Nope, I haven't seen any witness marks of anything in/on the motor.  But it was so freaking loud!  I thought I was about to lose a rod or something.

[machoneman]

Not sure either how that could be the cause of the noise but hey, it's not everyday one sees a cracked flywheel w/o a major blowup. Lucky, I guess.

Looks like the i.d. of flywheel crank flange was too tight (you mentioned it was a chore to take on and off) and the 'wheel wasn't seated 100% before the crank bolts were tightened. Could be a material flaw but I'll venture that when you had to draw-up the crank bolts with your torque wrench it clicked out before the 'wheel was fully seated. Would like to know the dimensions of flange i.d. versus the crank's o.d.  2X as well to closely checking both sides of the engine's thrust bearing for unusual wear.

A couple other things to look at include the ring gear pattern and the clutch disc hub. Rotate the 'wheel and see if the shiny wear marks from the starter gear move fore and aft (engine side to tranny side) as you rotate the wheel. Also, the disc's center splines may be messed up (loose on the input shaft) from not engaging 100% perpendicular to the crank pilot. The pilot bearing itself should also be closely inspected.   

Hope you have a blowproof bell as well. Checkout the holey sheetmetal in some of the streeters!

 http://www.google.com/search?q=flywheel+explosions&rls=com.microsoft:en-US:IE-Address&rlz=1I7GGHP_enUS533&tbm=isch&tbo=u&source=univ&sa=X&ei=c7jvUbq6LsGSyQG7vICYDA&ved=0CEkQsAQ&biw=1024&bih=566

[cjshaker]

Right about now, I'd say that noise was a blessing! That flywheel was major damage just waiting to happen! I'd be looking real close inside that bellhousing too. Things can get pretty tight in there.

Just out of curiousity, what brand flywheel was it?

[lovehamr]

The flywheel is a fidanza and the bell is a quicktime.  Other than that small visible crack there is nothing indicating a problem.  The pilot bearing is perfect and smooth in operation and both side of the thrust bearing are good.