1.6td Cracked prechambers dilema

[rumbling_caddy]

I have a cutom 1980 vw caddy that I swapped in a hydraulic 1.6D then turboed it with an mk1 oem setup.  It also have a Giles pump and TT 2.25" dowpipe.  Anyways it ran great up to 25 psi  for a few years before the head gasket blew late last year. That happened suddenly on the freeway and blowing out a lot of white smoke so I guess I had coolant when it blew.
 
 So I'm finally got around to fixing it this weekend.  When I examined the head gasket it didn't looked obvious to me what the problem was. I also had ARP head studs and I'm pretty sure that was torqued down well.  The only obvious flaws I saw was in the head.  Yes there are typical cracks between valves but it was like that when I bolt the head on years ago.  New to me are all the prechambers are cracked.  Two have small cracks and two have big cracks.  One looked kinda long like 1cm and the other is about 0.7 cm.  Could this be my problem?  Shouldn't the head gasket seal ok since it not only go around each cylinder but also around each prechamber?

I'll attached a few picture if someone have more experience with how bad prechambers have to be before somthing needs to be done about it.  I have another head that I pounded out two uncracked prechambers for parts.  I put an old head bolt though the injector hole and used a big hammer to get those out.  That worked but I messed up the injector threads.  Good thing that was on a bad head I didn't care about

Anyways I like a few options to choose before putting my engine back together.   Are my two cracked prechamber really that bad?

1) Do nothing about the two cracked prechambers and hope the new head gaskets seals ok
2) Replace the two large cracked prechambers with the good ones I pulled from the bad head.  A couple risky issue with this option.  I could crack the area around an injector since who knows how stuck the 1 or 2 injectors I need to remove are.  I could mess up an injector thread if I'm not careful pounding out the two bad prechambers.  How do people put back the prechambers to make sure it's flush or sligthly below the head deck?  Is a hammer and a block of wood enough or  do I need to figure how to press them in?
3) Look for a different good used 1.6D head
4) Get my current head professionally checked out and let the shop deal with the two  cracked prechambers.  I could give them the two good used prechambers I pulled.

I would like to get some opinions from IDI diesel gurus before I take a course of action to get my caddy back on the road...









I pulled these two prechambers from my 1.6D bad head


 

[libbydiesel]

You should replace all of the cracked pre-chambers.  The cracks can grow very quickly.  This is what happens when the cracks reach the edge of the pre-chamber insert:





Your inserts from your NA head probably aren't the same diameter.  A little bit ago I got some new inserts.  Details in this thread:  http://vwdiesel.net/forum/index.php/topic,36096.msg340064.html#msg340064

[rumbling_caddy]

Thanks for the reply.  I'll double check  to make sure the prechambers I pulled from the bad head is the same diameter as what I need.   Oh I don't have a real 1.6td since I added the turbo setup.   I other weird thing i noticed from the pictures I posted is that the two prechambers I pulled don't have a little dimple next to the big hole.  What does that dimple mean anyways?

[libbydiesel]

All of the dimpled inserts I've seen were from turbo heads and were the smaller diameter.  You should buff the other inserts to a shine.  That's the only way to see if they are cracked.

[rumbling_caddy]

Thanks libbydiesel.  I guess I do have a 1.6td head then...

Anyways my problem is more than just those cracked prechamber inserts.  I decided to test the head by putting everything back together with a new headgasket.   Sure enough it runs...but exhaust is coming out of the coolant flange...So I need a while new head then I guess