1991 7.3 overhauled a year ago. IP started having to be watered to get it to start hot. At the same time it started to really rattling at idle. Replaced IP and problem idle noise is still there. Come off idle it sounds good runs good. Oil pressure is good temp is good. Seems to be noisier underneath and and in the torque converter area. TC nuts are tight it is a c6. Any ideas folks

 

Cracked flexplate maybe, although those tend to sound like a can of rocks off idle.

 

Try pressing the mechanical advance lever on the driver's side of the IP at idle. If you press on the bottom side or pull on the top side, it will retard the timing by a few degrees.
If the noise goes away, it's timing related.

 

Will give that a try

 

That didn't change anything

 

Did the tone of the engine change? If not, you're doing something wrong.
It might not change your clatter, but it should change the engine tone.

Make sure you are pushing on the bottom of the lever, or pulling on the top.
Not sure about the lever? If you push the throttle lever towards full throttle(or have someone step on the gas), you'll see the lever on the side move in and out.

 

i agree with Jared on the cracked flex plate. makes noise at idle but goes away under power.

 

It is the flex plate. where can you buy just the tin flex plate.

 

here is one on evilbay with the outer anticrack ring. not sure if it is for the C-6 though:
http://www.ebay.com/itm/1987-1991-FORD-6-9-7-3-IDI-DIESEL-FLEX-PLATE-ASSEMBLY-FOR-AUTO-TRANSMISSION-/221844712848?hash=item33a6f9ad90&vxp=mtr
here is another one, but like the one above they do not say if it came off a C-6 or an E4OD.
and i don't know if there is a difference or not.
http://www.ebay.com/itm/88-89-90-95-96-97-FORD-F350-FLYWHEEL-FLEX-PLATE-A-T-8-445-7-3L-DIESEL-48463-/252027445483?hash=item3aae01a0eb&vxp=mtr

 

Those are e4od I didn't find any on ebay

 

as per www.car-part,com in Oklahoma:

<table width="100%" border="1" cellpadding="4" cellspacing="0"><tbody><tr><td>1984
Flywheel/Flexplate
Ford Truck 250</td><td>AUTO,RING GEAR</td><td align="center">C</td><td>980208</td><td align="center">$45</td><td>Bud's Salvage USA-OK(Aline) E-mail 1-800-375-2837 1-580-463-2424</td></tr><tr><td>1986
Flywheel/Flexplate
</td><td>FLY W-O FLEX PLATE</td><td align="center"> </td><td>KS793</td><td align="center">$45</td><td>Bud's Salvage USA-OK(Aline) E-mail 1-800-375-2837 1-580-463-2424</td></tr><tr><td>1987
Flywheel/Flexplate
Ford Truck F250</td><td>FLEX PLATE ONLY</td><td align="center"> </td><td>NOF</td><td align="center">$Call</td><td>Lawton Auto Parts USA-OK(Lawton) E-mail 888-355-7758 / 580-355-7757</td></tr></tbody></table>

 

Got it fixed. I realized the parts truck had one setting in the back seat. thanks for the all the help