how do i replace the injector seals on a D7E 47a

It won't be the rubber dirt seals causing a leak but one of the three metal to metal joints between the pipe and injector holder, the holder and injector and the pre-chamber and injector. Undo the pipe, then the top nut then lift out the injector and holder, make sure all three sealing areas are clean, use a piece of wood carved to the shape of the injector to clean the seat in the chamber and only use an abrasive just coarse enough to clean the surfaces, screw the injector onto the holder finger tight only and torque the big nut back down to 100 to 110 lbs ft. If I am a little out here, I'm sure OM has the correct figure.
If the injector is deformed where the holder screws in, change it, you will never stop the leak, if you have to change injectors they come as a 'valve service group' in a blister pack complete with seals and the instruction on how to change them.

Take it apart, inspect and clean, reassemble and then consider ordering new parts along with the seals that keep dirt out of the cracks.

I have seen the end of the injector lines be damaged and no amount of tightening would stop the leak, so inspect everything carefully.

Have also seen one that for some reason could not be tightened properly with the rubber seal under the line nut. Took the seal off and it tightened up perfectly and stopped leaking.........not sure what that is about, but it was a simple fix.

If by taking off the top dirt seal which has a steel reinforcement in it the leak stops, it means that the top nut has been previously overtightened and squashed the nozzle. The injector line ends leak when they are scratched because they have been pulled sideways off the threads after the nut has been undone, as with everything, a little care goes a long way in reducing future problems,.

Hi catsilver,
Close enough on the retainer nut torque......105 ft-lb.

Line nuts 25-35 ft-lb.

Severe over torquing results in distortion.

thanks all for the info & to old magnet for the pic. Is good to see where the seals are. The seals should be here today & i will do it on saturday. The dozer was near a flowing artesian bore so i was able to get the heads squeaky clean with the hot water. The pipe to injector connection on all 4 are ok.

Again, the seals are to keep dirt and water out, won't do a thing to prevent leaking. Fuel tight depends on mechanical sealing.

i pulled out the leaky injector yesterday. I didn't think that the holding nut was 105 pounds tight. I noticed that the injector screws apart & was quite loose. How tight should it be before i put it back into the precombustion chamber?

The injector nozzle screws on finger tight only.