freightliner fuel cap leak tip

Actually? If DOT gets in a tizzy? They can get you for having a fuel cap defect. Most fuel caps must be non-sparking, hence why your tank and cap are aluminum. When I say sparking, if you strike steel you can get a spark from it. Granted DOT wont know anything about that unless they have been told.

Gas lids/caps are supposed to be made of plastic, aluminum or brass. Just a heads up.

 

Th reason a Freightliner fuel cap leaks is the seal is in the tank, top lip and if you can not hit the hole, with the fuel nozzle you will damage it.
Many fuel tanks on Class 6&7 are steel with steel chains and clips, the cap may be brass but the rest is steel.

 

Sorry, wasn't trying to be a hater. Just making a wise crack. It's just for grins. I'll try to refrain in the future.

 

How would I know if the tank is vented?

 

I did this to mine and no leaks, used
1 5/8" plug from Amazon. If you take the plug apart and trim about a third of the rubber off, your caps won't bind. The trouble is the plug goes into the cap too deep and prevents normal operation. Do this fix and get your tanks polished!