89 Renix 4.0 auto metallic from what sounds like the bellhousing area

Been chasing this a bit on another board, now I'm a bit further in thought I'd ask here. Background was playing in a mud pit killed my alternator. Replaced that but got this horrible metallic grating after everything dried out. Cliff notes:

• Oil level looks fine
• Alternator is new
• Starter is very nearly new - pulled it again and inspected, seems fine
• Removed the serpentine, didn't change the noise. Replaced it anyway. Pulleys seemed OK. Harmonic balancer not hitting anything
• Fans not hitting anything
• Got worse -- I think -- after taking off the inspection plate and hosing out the dried mud
• Flex plate doesn't look cracked
• Flex plate bolts are tight
• Rear main seal (and several others) replaced later September 2013

Looking at other folks' problem videos this doesn't sound like rod bearings. Engine starts and runs fine, but haven't been driving it until I figure it out, so I don't know if/how the noise varies with speed.

Dropping the transmission for a good look might make sense, but it'll take time I don't really have, and skills I'll need to learn as I go. I'm not too into paying a shop for a value-of-vehicle fishing expedition if I can avoid it. Any thoughts?

Videos of sound when engine running, and one of it sat cold with me turning the crank.

http://www.youtube.com/watch?v=VpSN00751QA

http://www.youtube.com/watch?v=A2PpcLbqbXI

could you have gotten mud and / or rocks into the bell area? depending on how hard you were on it, maybe a broken converter bolt?

CompleteCherokee said:

could you have gotten mud and / or rocks into the bell area? depending on how hard you were on it, maybe a broken converter bolt?

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There was mud in there alright. The inspection plate was in place and not deformed, so there was a small gap for muddy water to get in. Looks like plenty did and when it dried out left a fine, dusty mud. Hosed that out. When you say torque converter bolt, which ones are you talking about (I checked the outer bolts on the flex plate, not sure what others are up there.)

The bolts that hold the converter to the flexplate, which are on the perimeter. If those are all tight / good, then either you still have debris stuck inside the bell or it could be something else. Sounds like its time to use a long screwdriver and narrow down where the sound is coming from. Also, check the trans fluid and oil to make sure they are in good condition / no metal shavings.

i've seen flex plates crack in a circle around the crank flange. it will still transfer the power because the 2 pieces are together like a puzzle. it just rattles alot.
do you get any new noise of any kind when you start it?
it's hard to troubleshoot without pulling the trans.

sidriptide said:

i've seen flex plates crack in a circle around the crank flange. it will still transfer the power because the 2 pieces are together like a puzzle. it just rattles alot.
do you get any new noise of any kind when you start it?
it's hard to troubleshoot without pulling the trans.

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