transmission chatter

'08 KW T660 Cummins ISX CM871 (I figger y'all know this truck by now, but still...LoL)

Started truck to let (4) brand new batteries charge today and went inside to watch television. Running at high idle, I knew it would get warm, so I turned the engine fan on and just let the engine run for a couple hours.

Went back outside to shut truck off and all I hear is a lot of clattering. Shut off fan and that didn't help any, so it's not the fan... Step on clutch and not much happens but when I engage the clutch brake all the clattering stops. Let clutch back out and noise resumes. Walk around and listen with hood open and it *sounds* like a lot of the noise is in the (recently replaced) head. Again, engaging the clutch brake quiets the racket.

It's the same EF tranny that doesn't like going into 4th, 10th or 11th and recent LOF service showed glitter on the trans magnetic plug. Trans has been on list of things to do, so it isn't catching me unawares.

My question is: do you think the clattering is transmission or valve train?

Let me know if more information is needed

 

Just fur for the time being. Bearing and seal is a plausible assumption, I think, as the flywheel housing has what resembles diarrhea pooled in it (that's new). Snap ring or sync also sounds about right. Have been babying those 3 gears for a while now. (Skipping 4th completely and trying to skip 10th when possible)

 

Im just hoping it holds together long enough to get from Tifton, GA to Columbus, NE. Will probably bounce rather than risk putting it under a load.

 

Can someone help decipher this tag? I know it's a "low inertia overdrive" , that it has an 1850 torque rating and 13 gears. What does the 9 represent and does the long number on the bottom mean anything? Lastly, would I benefit from having 5 more gears (just to get heavier loads moving)? If I'm changing boxes I might as do right by the engine....

 

I've driven an 18 before and, while I rarely split the low side, it was nice being able to maintain momentum on those heavy uphill starts.