Spent 11 hours chasing a leak on a 300 HP firetube only to find a pinhole in a $4 gasket
Pulled the rear head twice, re-rolled two tubes, and swapped the sight glass before I finally pressure tested the gasket seat and watched it bubble at 5 psi, so now I want to know if you guys soap test fittings before you tear a whole unit down or do you go straight to the tubes like I did.
Been there man, except I once spent a whole shift on a boiler that turned out to just need the gas valve cracked open a hair more. That was a fun one to explain to the boss. Soap test is cheap and fast, why not start there.