Well something has went wrong some where. I have a 7fb12885 400hp cat jwac 3406b in a 84 Pete 359, that I just rebuilt myself. I’ve been turning wrenches since I was old enough to tell the difference between a wrench and a socket, so I felt pretty comfortable in rebuilding my engine. After completing rebuild truck fired and ran good sitting, except a little white smoke which I was throwing off as fuel problem do to fuel lines not seating. Got them seated up,and let the engine run til temp a couple of times, never at anything lower then 1200rpm, took it on a test run bobtail with about 30mins or so on the engine to start the ring break in and for a small test before putting a load on it. All was well plenty of power untill I get to the first hill a mile from the house and as soon as it starts the incline it fell on its face, barely made it to the top of the hill. As soon as it leveled out it stalled like out of fuel but started right back up like it ran out of fuel and was running smoothly again with what seemed like plenty of power going back down the hill and on level ground, but was now smoking white bad. Got it back to the house raised the hood still running very smoothly and coolant over flow tube was literally humming with air from coolant system. Hurried up and shut off truck. Oil level still good, coolant level a little low, and no leaks that I can see. Went to do research and the next day start to look it over and crank it up and cranked about half a crank and felt like hydro lock. With being upset I didn’t look at her for 3 days, decided to try again just for kicks and she cranked over fine for about 2 cranks like nothing was wrong and then seemed like it hydro locked again. Sorry for the long post just trying to give as much info as possible. Any ideals?
Oh forgot to mention that there was no coolant leaks or smoke before engine teardown, reason for rebuild was knocking and oil out exhaust, which ended up being #5 piston and rings, intake lifter on #6 was deformed, and bearings were showing there age, those were the major things the rest was just finding seals that had hardened. But like I said before engine teardown it never smoked white, just normal black when shifting and never lost a drip of coolant