I lost one of my copper washers awhile back and finally got around to ordering new washers and extra banjo bolts(to be safe).I pulled the part numbers from the "sticky" and got the parts from Cummins. The problem is the banjo bolts are no where near stock, not copper and much smaller holes. The washers were not copper either and had a rubber ring around the inside. Would this cause sealing issues?
Heres the numbers
P/N 3 ~ 4429 728 WASHER, Sealing (2 req).
P/N 4 ~ 4429 729 SCREW, Banjo Connector

 

Quite often the sealing washers on banjos are metal with a rubber lip. I've used these interchangeably with copper washers without any problem. Just be sure whatever you have fits properly. Make sure the rubber lip is actually contacting both surfaces that it has to seal, and that it feels snug around the bolt. be sure the length of the bolt is right, doesn't bottom out before making the fitting tight etc, proper diameter and threading, etc.

 

when I replaced my stock banjos with the larger id and tapped ones genos sells I found some copper washers at the local hardware store that have a closer tolerance id than the stock ones.

 

Good to know. I put a metal washer on my stock bolt and the rubber was snug enough but upon test driving it my boost gauge almost seemed to 'hang up'. Going 60km/h it read 0 psi but when I tapped my gauge the needle moved. What do you think is causing that?