I am having the head rebuilt on my D2 3J. Of course the head shop wants to remove the precombustion chambers to plane the head, which of course is the proper way to do it. They are not leaking and you know the old saying "if it's not broken, don't touch it" comes to mind.

Does anyone have any helpful tips on removing these, and can it even be done without the proper tool??

Are you sure the head needs to be planed? This is a Cat after all, not a Chev. Straight edge it all directions.

Some shops will give you a long song about how they won't guarantee the work unless they can "do it right", which to them is everything you could possibly immagine in a machine shop. The final call is yours; be just a little skeptical this time.

There is a special puller for them and it drops down over the two studs that clamps the nozzle down in and the chamber has threads in it that the tool screws down in and then it is made to turn the top of the tool and it pulls the chamber out.Maybe if your Cat dealer has one he would lend it to you as I,m sure they would very seldom use it.

How early a 3J is it?
Late D3400 used a hex drive removal tool that could be duplicated by welding a couple of nuts on a bolt. Sorry. don't remember the size.

The early units needed a special tool for removal as seen in the attachment.

I would make darned sure it needed surfacing.

I have taken the threads out of the head or at least damaged them while removing some procombustion chambers on parts engines. There is a tool to replace the thread, but it gets expensive.

Other than surfacing the head, I would judge the importance of removing them by the condition of the cooling system. If it's in bad rusty shape, then it might be a good idea to have a look at the PC chambers anyway. Leakers usually will show a clean head surface on that cylinder, no carbon!