no.7 cyclinder blows o-rings on injectors
 

2003 Ford F-450 S.D. Truck has had all injectors replaced in last 3 months. FICM is new,oil just changed. This is the three set of o-rings on no.7 injector. with bore scope sleeve looks good, all pressures on scanner ok. Drive truck on road runs good untill drop the hammer. Then it will stumble and blow black smoke, let off and it will run fine. Give it about 2 weeks and its towed back into shop hydro locked again. Check coolant ok, check oil over full alittle. pull glow plugs and fine fuel in n0.7 cyclinder has fuel in again. Need help please

Is the injector getting torqued down properly? Make sure the bolt hole is free of oil and clean. Usually they only burn up orings if they arent torqued down good. #7 is in a bad place easy for someone to get lazy and not get it tight enough.

Odd that it's the same cylinder multiple times. Black smoke means you're getting fuel, how's the turbo? Any idea what boost you're pushing? Turbo may just need a cleaning. Why on earth is it hydrolocking? From fuel?

Who's doing all this work to it? Ford dealer? Have they tried swapping two of the injectors around? For instance, put injector 7 in hole number 1 and injector 1 in hole number 7? It really wouldn't be any more work to do this if you're already in there pulling the injector for o-rings. Also most guys doing injectors will go past Ford's torque spec on them, because I've seen/heard of a LOT of cases where they torque to Ford's spec and then they loosen up.

Is the truck hydrolocking while it's sitting? I'd assume so cause if it was doing this running it would be catastrophic...

once the orings burn up itll either hydrolock after sitting and be a no start or some will start with a slight hiccup and white smoke heavily. Im thinking being so close to the hvac case #7 isnt getting torqued by whoever is doing the job. Usually I see #5 and/or #7 burnt up and loose.

Makes sense. I wonder if the injector could be the culprit too. You'd think if you were a tech working on this truck and saw it come back 3 times on the same cylinder you'd take extra care to have that injector torqued down, but who knows.

I wonder if it has a crack in the nozzle or something...

need more info here.

I would have to put a scope down the injector hole to make sure the old crush washer wasn't still in there, and also to see if anything wasn't messed up in the head

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Oh yeah, make sure to replace that sleeve cup no matter what, something has to be causing this, stock torque is not quite enough for the clamps as stated by others, tighten to stock torque then add a little uumph.