It's a hard call for sure. If the combustion chambers seal how can the water get into them from the area outside the cyl. seals? I don't see any indication of leakage to the cylinders in your photo. The leak, if it occurs, will be to the side of the block. A water leak to the cylinders will happen when the head gasket blows around the combustion chamber seal. Then it will blow compression into the cooling system and when the engine is off and pressure builds in the cooling system the water will follow the path back into the cylinder.

That condition can only happen if the head gasket blows at the cylinder seal ring on the head gasket.

It would have been better to see a photo with the head gasket and then without to analyze what happened. How many places were cracked in your block?

According to Carl Walck half the blocks they see for rebuilding are cracked, that means to find a block that is not cracked is very hard to do and even then there is no guarantee the block will not crack after you rebuild it. They repair the blocks that can be and use them.

Sean on the CJ2 site said that from a month after the block is cast at the foundry the block is machined and ready to assemble. That information was a death knoll to the L134 blocks. Cast iron has to be aged by letting it lay out in the weather for at least a few years to leach the acids and let it stress relieve. That means every engine they built was with a green cast iron block and probably the head as well.

The chance of finding a block without a crack somewhere or not needing a line bore for the mains and cam bores is like finding a needle in a hay stack. Chances are I could go through 5 blocks to find one uncracked one and there is no guarantee it won't crack next week in use.

If you tear these engines down and rebuild them without having the deck and head surfaced your asking for trouble. Remember it is a 60 year old block that has stress relieved it's self and is twisted and the likely hood of the deck surface and head ever sealing without being resurfaced is a real crap shoot at best.

The fact is I should have had the cam bores and main bores line bored but I choose not to. I still have a complete CJ2 engine and I will eventually tear it down and check it out. It may be a good block and if so I will build a short block for future use, at least I will prepare the block for use. 

There is one saving grace that I do. I don't tighten the radiator cap and I use a 160 deg thermostat. I also don't care if water leaks to the outside of the head and block as long as it stays out of the cylinders. Since I had the block surfaced and the head surfaced it should seal very good.  

Carl:
I feel for you. I went the route of pinning my original L-head and having it decked and so on. Cyls 2 & 3 were bored and sleeved due to bad scoring on their walls. The new sleeves prevented any coolant from passing through them. I always had issues with overheating and coolant getting in my oil. I chased the little gremlins all over that engine and replaced numerous head gaskets and even the head.

I wish I had a camera in hand to take some more pics of that old block, but was lucky to get a few with a cell phone.

Interesting observation: After the old block sat out in the weather for a couple weeks, the cracks became highlighted by a line of rust that extended past the end point of the cracks via visual observation by almost 1/2 inch! I believe my problem was the hot coolant being pushed up between the gasket and head... regardless of what type of gasket I used or how often I checked the torque on the head nuts.

I believe all of our 2A and 3A engines were experimental! Ever look at the casting marks? Looks like they were playing around with the recipe for their cast iron. Hmmm... let's see what happens if we add more chrome to this batch of blocks!  

Boy Carl,
Those are the same thoughts I was telling myself last summer when I struggeled with engine rebuilds, i can feel the energy.  Just keep telling yourself that you are enjoying this, and eventually you will !!! LOL

Todd

Pardon my ignorance, but what is siamesed?  Thats a new one on me.

Update, I've had some interruptions like replacing pistons, tractor down and getting a hone among others. So I got the .040" over pistons, bored the cylinders, was given a Sunnen AN hone and bought some stones for it. I got the tractor hyd working again so I hauled the block to the pole barn to pressure wash it and paint it with rust protection primer. Then I relaxed with a whiskey and Coke while I watched the paint dry.



Today I have the block back on the engine stand and made a valve guide driver/installer. The large round part is a spacer to install the guides to the correct depth, 1" and 1 5/16". If you replace your valve guides be sure to get the correct guides. Some dealers sell only one length guide and that is not correct.

That's my radio head phones and it keeps me from hearing a helicopter when it falls on me.

I was going right fine installing the valve guides and then, OH CRAP, I shattered the top of the fourth exh guide. Well, the truth is I knew it might happen but was hoping the tool would last longer. The soft metal driver expanded and cracked the top of the guide. I did update #2 by making a sleeve of tool steel and I installed the four intake guides with no issues. I had to drive the guide out from the bottom and that required another tool  . Update #1 was when I realized I misjudged the shoulder to set the guide depth. 

I have another exh guide ordered and while waiting will proceed with cleaning the oil galleys and laying the crank. I have to dial indicate the bell housing before I do a full assembly so there will be a lot of putting together, measuring and taking apart. I'm sure glad this didn't happen in August. I knew this rebuild was not going to go fast. I'm starting to think I am to picky and think I am rebuilding a pocket watch instead of a Jeep engine. 

I am transferring a post from the old site.

The crank is laid in and plastigaged and the pistons assembled and punched in the holes and plastigaged and everything is good. One thing that puzzled me a bit is the wrist pin clamping bolt is on opposite side on two of the rods. I read the manual and it told how the slots in the piston goes opposite the oil hole in the rod and that makes the numbers on the rod go toward the cam. Then I picked up the old piston and rod assemblies and looked them over and noticed the wrist pin clamp bolts are on the cam side on #1 and #3 and the opposite side on #2 and #4. I am still wondering why Willys did that.   That's a good way to get the rods in backwards as I see it. There have been a few things that I wondered why would they do it that way but it is what it is so I just move on along.

Tomorrow I will grind the valve seats and put the valves in. Maybe more if the seat grinding goes well.