real nasty knock/rattle.... help please

we finished up cleaning out the garage today and i just went to put the mustang back in it, and when i pulled it in it was making a really bad rattling noise. its very spuratic, and it doesnt change a lot with engine rpm. my dad says that it doesnt sound like a rod knock, but i've never heard one so i dont really know. i havent had a chance to try to pinpoint it with a stethoscope, but it sounds like its coming from the rear of the engine, possibly the bellhousing. but whatever it is, its LOUD. its a very audible "clack" sound, that sometimes changes pitch a bit.

oil pressure is normal, oil looks fine, coolant looks fine, its not overheating.

any ideas what to check next?

jesserose17 said:

Sounds like torque converter may be going bad.....

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sorry, should have specified that its a standard. if i find a torque converter in there i would bet its presence is the problem.

i'm not quite sure what you're refering to with the bendix? i'm guessing that this is part of the starter that is getting hung up on the flywheel ring gear? i have had troubles with the starter gear kinda lagging and rattleing against the flywheel before, but it normally went away after 5-10 seconds. you think that maybe this has just gotten really bad?

it makes me shudder to think about pulling the starter and possibly the trans yet again.

SuperDave said:

You will best learn the source of your "noise" by thinking from the present to the past. The car did NOT develop this noise mysteriously on it's own. Rather than tell you an answer, YOU should discover it from thinking through the sequence of events between the last time that you lastdrove the car and the discovery of the "noise".

-Have you actually looked under the hood?
-Has any "work" been done to the car? If so, what and by whom?
-Are you sure the CAT didn't get trapped under the hood?
-When does the noise begin? On startup or when moving?
-etc

As is so often the case, how well and how campletely the story is told is CRITICAL to success in solving the problem.

Merry Christmas,

SuperDave

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Well the whole story is that on monday i fired her up after sitting for most of the winter so far, backed down the driveway, went around the block, drove back up the driveway and parked her beside the garage where she sat covered up til yesterday evening. Yesterday i started her up and again backed down the driveway, then started back up the driveway, stalled it once, and finally drove back into the garage where i noticed the noise.

I've looked around under the hood and havent been able to determine where its coming from, no cats, no balls, just clacking. Its there when the engine is just idling and when you rev it, it doesnt change when the clutch is pressed or the car is shifted through the gears. It also doesnt seem to change with engine speed.

The last work i did on the car was a transmission swap. The car has only been driven about 100 miles since then, but no such noise until this week. I did not replace the clutch when i did the trans. As far as i know it is still the original flywheel and clutch.

Occasionally i've noticed a noisy valve when its cold, but nothing this extreme.

Its a mostly stock 4 barrel 289.