Hey guys...

I have a question for you all. This is concerning an industrial Cummins out of a late 80's Frieghtliner striaght/grain truck.

We have a small maybe 3/8 line running from some sort of junction box above the air compressor......to the fan shroud. Odd as this sounds, it runs through the fan shroud via a 3/8 45 deg elbow, and comes out on the inside of the fan shroud as a reduced nipple.

The problem here is that the truck has been weeping air out via this nipple and were not sure why. If the truck is shut down for a period of time longer than 8-10 mins...we lose a significant amount of air out of both service and supply tanks.

For the time being we have been able to plug this nipple....but this is probably not the best fix.....lol.

Thanks for any help.

 

Two things come to mind. The first is that it goes into the front of the fan clutch to operate it. They still use air operated fan clutches on new trucks. On my 2004 International worktruck, air pressure is present to the clutch when it's not locked up.

The other thing is that it was used to operate wind shutters in front of the radiator. You'd be able to see the shutters in front of the radiator either in front or just behind the grill if this was the case.

 

I believe that it is the air line that actuates your fan clutch. Many were and still are air actuated with an electrical sensor that tells them when to turn on or off

 

either the air line for the clutch, the m11 series engines(6 cylinder) use this arrangement.

if that isnt it, does it go through a set of coils and then to a reservoir? it could be a cooler for the air after being compressed.