DIY: Oil Cooler (scratch built install, lottsa pics).....>.

Billy830

I would not call them precise fittings, knicks or any imperfections can affect the seal, mostly under high pressure conditions, for which you would use stainless fittings. Aluminium is not considered high pressure and there for should be inspected for knicks or any imperfections(we drop things and aluminum is soft). Voishan seals are made for AN fittings and will compress and make a perfect seal but these are generally used for high pressure applications but will work for low pressure apps as well.
We are only working with a low presure system.
The leaking or weeping at the hose and braid says to me that the hose is not properly installed on the fitting (cut straight) piece of braid has overlapped the hose end or has a bend to close to the fitting that it has distorted the shape of the hose on the fitting and for me I think that that the latter is the main problem with hoses popping off. Aluminum fittings can be over torqued and strip the threads unlike stainless. Snug up the fitting and take 1/4 final turn.
On pipe threads always use teflon tape. Start 1/16-1/8" back from end start to wrap counter clockwise and only take 2 wraps, don't over do it. Becarefull that no tape over laps the end of the fitting as this will get cut off and get into the system. If you remove a pipe fitting with teflon tape on it use a soft wire brush (tape will become clear after use and you may not notice it )to remove excess teflon tape, do not just tape over the fitting. Inspect the other fitting end for left over teflon and remove any that has been left behind if not this stuff will make its way into the system when you reinstall the fittings.

Check your routing and clamping make sure that the bends are not severe.