Trying to put in new plunger/head seal(?) on the IP.

[lyeinyoureye]

My IP is leaking a fair bit from the head, or whatever the part that the injector lines plug into is called. I'm trying to swap out the seal via the in-car method I've seen mentioned on this and other forums, where I loosen the torx bits holding the head on, cut off the old seal, and then stretch the new seal over the pump head and slide it into place first on the bottom and then on the top by removing and tightening the screw sets in pairs after I slide the seal into place.

My problem is that the head doesn't seem to want to budge. I've loosened all five of the torx bolts, the bolt that holds the cold start bracket on, and even the bolt in the center, and the head won't budge. Do I need to loosen the injector line ports/bolts too, or do I just need to give the head a good thump with a rubber mallet? I'm also wondering which seal I need in my Bosch kit. I'm 99% sure it's the largest circular seal, but the kit seal seems to be light colored while the seals I've seen in pictures are all darker. Does the difference in color mean anything?

[745 turbogreasel]

You may also want to hold tension on the plunger.

with the 4 perimeter bolts out, you should be free exc. external bracketry which may be in the way.
I'd try  for rotation before  whack to free it up..

[Smokey Eddy]

You are correct in assuming the larger circular seal is the one you need. I've done this before. It's a very tight stretch to get the new on over there and I would suggest cleaning that whole area very carfeully and thoroughly before doing so. You only need to undo the hex bolts holding the end on. The bolt in the middle is just a plug covering something used for setting the timing. Keep it in there. The outlets don't hold anything together except for the inner workings of those valves. Do not loosen them, you don't need to.
The issue here is materials of two kinds mating together and oxidizing beside each other. The end is iron and the pump body is steel. (i think) anyways, you've got some crap in there holding it together. I would spray some penetrating oil on there (like WD40) since you are going to clean it afterwards and replace the seal anyways and just keep working away at getting it to budge. if you have one, you could put an enormous pipe wrench on the pump end (as it is square) and try wraping the wrench with a hammer to break free any junk thats giving you the issue. Be careful though, the pump is easily the most sensitive (and expensive) piece of equipment on the car. I would use heat as an absolute last resort as there will be diesel everywhere and you generally dont want to get precision machined bits too hot otherwise they will warp and no longer work.
I'm confident you just need to turn a little more red and fight with it a little more...

[libbydiesel]

Don't leave the center bolt in place.  You need to remove it and install a spacer to keep pressure on the plunger in order to keep the shim at the base of the plunger from falling out of place.  Tighten the center bolt down on the spacer a little, loosen the outer bolts a little, tighten the inner one a little, etc...  Some people have had success without keeping pressure on the plunger due to the surface tension of the diesel fuel keeping the shim in place.  Others have not been so lucky and have turned their pump into a pile of shrapnel because of not keeping pressure on the plunger.

[lyeinyoureye]

Thanks for the tips! I found a howto on it using some of the keywords in this post and it mentions rotating the engine to 90 degrees after TDC. Do I need to do this prior to replacement?

1.5. EDIT: Rotate the engine by hand so that the injection pump plunger is not being pushed by the camplate (90° crank after TDC). You can remove the timing hole bolt from the center of the pump head and measure using a dial indicator to find when the pump plunger is not moving.

[Smokey Eddy]

Don't leave the center bolt in place.  You need to remove it and install a spacer to keep pressure on the plunger in order to keep the shim at the base of the plunger from falling out of place.  Tighten the center bolt down on the spacer a little, loosen the outer bolts a little, tighten the inner one a little, etc...  Some people have had success without keeping pressure on the plunger due to the surface tension of the diesel fuel keeping the shim in place.  Others have not been so lucky and have turned their pump into a pile of shrapnel because of not keeping pressure on the plunger.

Holy smokes, i consider my self one of the lucky ones then. Sheesh.

[745 turbogreasel]

If the washer between the plunger and roller ring falls, your day is done, and nothing really holds it in place.

[lyeinyoureye]

I read through the thread and it looks like moving the engine to 90 degrees after TDC is a secondary precaution based on potentially screwing up the longer bolt or bolt/spacer that keeps the plunger under tension.

The potential problem I see is that the cam roller shafts are less than the 1/4". If the plunger is at the bottom of the injection stroke, then when the head is removed the necessary 1/4" for o-ring access, then there is the possibility of one or both of the upper cam rollers flopping toward the head and the shaft falling toward the plunger shaft enough to cause problems while reassembling. On reasssembly, the cam roller shaft could then remain lodged between the cam plate center circle and the cam roller housing and cause the plunger to remain at the top of the injection stroke at all times. Not good.

If the pump/engine is rotated so that the plunger is at the top of the injection stroke, then when the head is loosened there is not enough space for the cam roller shafts to move and cause any problems. Another possibility would be to get a bolt with threads of the same size/pitch as the timing hole plug bolt, but considerably longer. The bolt could then be placed in the timing hole and tightened down onto the plunger as the pump head bolts are loosened to keep the plunger and cam firmly pressed againt the cam rollers. Then when assembling the pump, the bolt would need to be loosened while the torx bolts were tightened. The bolt in the timing hole would be more successful and easier if done correcly, but would carry slightly more risk of damaging the plunger if tightened too much or not loosened enough while tightening the torx bolt.