Not sure where this noise is coming from. 12.7 detroit . Century

Its apparent when going above 60. It seems like it's coming from under the shift boot ( tranny) . Changed bearing in the rear end 6 months ago and u joints and hanger bearing 4 months . The noise goes away when I coast . If the drive line was off , I know I will have a grind or chatter . I checked ride height and it's fine. Even if the ride height valve was leaking it shouldn't do that , unless the leak was excessive and causing the bags to sit low . My question is, the grease fitting on these Eaton fuller transmissions. I know where one is, but not the other . The pilot bearing grease fitting is right inside an opening with a quarter inch hose . Where is the other grease fitting on the tranny ? . I am thinking it could also be a warped intake manifold sucking in air .

 

Clutch fork bushings on both sides , besides the one under . Gotcha. Then I will check the intake . Sometimes it sounds like a hissing noise

 

I just had the rad. welded and they found a leaking cac. The noise was there before I changed the radio and had them weld the cac . Time to check every hose from the cooler to intake . Wish I had a smoke test .

 

The noise was there before the weld. I will pop the hood and check all the intake hoses. With a warped intake , I wouldn't be able to tell , unless I take it off . Then I will work my way to greasing the tranny

 

Definitely an air leak . I bumped up the idle at 1300rpm, and found a leak on a plug / bolt that runs into the air intake manifold/ tube. I plugged it up with a better bolt and continued spraying the soapy bottle . I still hear the hissing sound. just dont know where it could be coming from. Wish I had a smoke tester , but that seal to be expensive