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Discussion Starter #1
It really sounds like it is coming from the back of the oil pan, but you can feel the whole motor vibrating.
Any ideas? It is not the A/C compressor bearing, doesn't make the noise unless it is in gear.
You see the rpms drop to just about 500 and it starts rattling. Touch the gas and it is gone, shift out of gear and it is gone.
I'm thinking it is related to the low RPMs?
Thanks for any help.
 

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Possible torque converter issue?
Just had mine replaced, but I wouldn't describe the sound mine was making how you describe yours so not sure..
 

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Discussion Starter #3
Not sure, one diagnosis was a broken flex plate. Checked it all around through the starter hole... looked great and all the nuts were tight. Seems it is not the a/c clutch or pulley bearing, that spins smooth by hand without the belt. And no noise when the a/c is running. Only when In gear AND a/c on, change either one and it is gone. Only at that very low rpm when the a/c and the trans. are putting a load on the engine. Really seems like it is lower engine. One idea was that it could have spun a crankshaft main bearing.. I don't know.
 

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Not sure, one diagnosis was a broken flex plate. Checked it all around through the starter hole... looked great and all the nuts were tight. Seems it is not the a/c clutch or pulley bearing, that spins smooth by hand without the belt. And no noise when the a/c is running. Only when In gear AND a/c on, change either one and it is gone. Only at that very low rpm when the a/c and the trans. are putting a load on the engine. Really seems like it is lower engine. One idea was that it could have spun a crankshaft main bearing.. I don't know.
If you spun a bearing your motor would sound horrible all the time. It is a very distinct sound that speeds up with rpm. You can rule out a spun bearing
 

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Discussion Starter #5
dd

Thanks for that, I am worried this thing will come apart.
For an update: I took it to the dealership and they swore it was the water pump. I changed it out and still there. Now it does it without the A/C running, just in gear. So, pointing me to the transmission internals or something.
When it is rattling and you tap the gas, it seems to rattle a bit faster as it revs up to 800rpm before it quickly goes away.

I took the belts off and ran it, still rattling, so not anything on the front of the motor..

Only other posts I have seen is maybe it is the camshaft synchronizers / phasers?
 

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Discussion Starter #7
Well finally got it fixed. It slowly got worse but never easily identified. Was something internal to the torque converter. Replaced rear main and front trans seal while in there, new flexplate, even though it looked fine $50. And torque converter, no more rattle!
 

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Good to hear. Thanks for the update!
 
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