air compressor noise

[robertglines1]

60 series detroit.  Was standing next to engine. It has been started for 1 minute.  Was and still is building air normally.  A fairly loud and rattling noise started (doesn't sound like rod) and stays.  Function is not affected.   Takes the same amount of time to start noise each time.  The fuel pump is driven off back of the air compressor.  My first response was to change compressor but that doesn't give me a reason and might not cure the problem if it is one. help me think this thru.   Bob

[B_K]

Hmm, that sounds puzzling.
If it doesn't sound like a rod and still performs the same I'd have no clue!
If on the other hand it wasn't producing as much or any air I'd suggest checking out the safety pop-off valve on the compressor head.
But it doesn't sound like that's the problem with yours.
I wonder if maybe you have a stuck unloader valve or something?
Maybe YODA will chime in he always has an idea that is usually dead on!
  BK 

[Dave5Cs]

Bob if you are sure it is coming from the compressor get out the short piece of hose to ear thing and see exactly where on the compressor?.... unloaders should be on the top area. That's that only thing besides the rods or a broken gear tooth that it could be.....

[luvrbus]

Probably just carbon build up or the discharge hose has a restriction going to the drier but check the oil supply line to be safe

[robertglines1]

will ck oil supply. new delivery line from air compressor to dryer to wet tank.. Had  been working normal for 6 months.(no noise) the air supply  is thru intake manifold.  On gear option /would it not do it immediate at start up?  Sitting has been my biggest challenge even to new parts.  Thanks!  Bob     One thing/variable is I have shop air hooked up to aux air dryer in front steering compartment.