View Full Version : AN ORB Fittings - Fuel Leak
cv2065
04-13-2025, 04:30 PM
Had a couple of fuel leaks today when I first tested the system. When I installed my AN ORB fittings a while back, I was able to screw them into the fuel filter by hand until they bottomed out. Thought there would be some resistance. I believe there is a chamfer where the o ring seats. Not sure why I’m still getting leakage but I thought that I might when I was installing them initially.
These are Aeromotive fittings. I’m assuming that these type of fittings are all made to the same standards. I thought about using fittings from the fuel filter manufacturer (Redhorse) but not sure that would make a difference. Anyone use high temp thread sealant on the straight side of these fittings? I wouldn’t think it would be necessary.
rich grsc
04-13-2025, 05:30 PM
Are you sue it's ORB, and NPT?
cv2065
04-13-2025, 07:05 PM
Are you sue it's ORB, and NPT?
Yes, the fittings and filter both are ORB. Here’s the filter:
https://www.redhorseperformance.com/fuel-injection-filter-inlet-outlet-08an-female-black/
PNWTim
04-14-2025, 08:42 AM
If the filter came with fittings I would use those. May be an O-ring issue or something else. You should not need to use sealant.
tnt_motorsports
04-14-2025, 08:47 AM
are the o-rings fuel compatible? Did you get fittings with o-rings installed or did you buy them separately?
cv2065
04-14-2025, 08:57 AM
are the o-rings fuel compatible? Did you get fittings with o-rings installed or did you buy them separately?
Yes, they were included with the fittings and I believe are nitrile rubber.
Edit: Just spoke with Redhorse and we compared o-ring thickness between theirs and Aeromotive. Aeromotive o-ring thickness was .07". The o-rings from Redhorse are .083", or a 15% difference in thickness. I thought all of these fittings were made the same, but apparently, they can differ with the o-ring sizes.
I found that the thread depth of ORB ports is not strictly defined in the spec. The Aeromotive pump I used had very shallow threads, and the fittings I purchased would not seal. I swapped them out with the fittings Aeromotive recommended, and no leaks.
Its Bruce
04-17-2025, 02:23 PM
I recommend oiling/greasing the o-rings with a compliant lube before sending them home. This will increase the chance of proper seating and not clipping or tearing upon install.