Would the pro builders please look

[66FAIRLANE]

at the pics of the deck cracks in my post below (last pics) & offer opinion. Thanks.

http://fepower.net/simplemachinesforum/index.php?topic=5877.15

[blykins]

I personally wouldn't be concerned about them.  I see those kinds of cracks all the time with factory FE blocks and even on some *ahem* 400 Chevy blocks.  They have never given me any trouble, but I always try and address them one way or the other:  either by using thread sealant (if the crack goes down), or by using silicone in that area.  You could also run a bottle of Ceramic Seal through the coolant system if you wished.

[jayb]

If you don't see any other potential sources for the leak, I think it has to be from those cracks.  I'd force some sealer into them, and then run the motor with Moroso Ceramic Seal for a few hours.  That Moroso stuff seems to really work, I've fixed leaks on welded up SOHC heads before with that stuff...

[Falcon67]

X3 on the Moroso Ceramic Seal.  Good stuff, works well.  Sealed up a external block crack in one of my 351Cs that was about an inch long.  Held for a year (full race season) until I could pull the engine and pin up the crack.

[66FAIRLANE]

Yes I put it in this engine when I first built it 20 years ago and then not after a freshen about 11 years ago. I just cant see those cracks dumping that much coolant in so quickly and the head bolt holes dont see the crankcase.

[blykins]

Yes I put it in this engine when I first built it 20 years ago and then not after a freshen about 11 years ago. I just cant see those cracks dumping that much coolant in so quickly and the head bolt holes dont see the crankcase.

The head bolts don't see the crankcase, but there is a remote possibility that the water can go through the crack from the water jacket into the bolt hole, then wick up and out from underneath the bolt head, which would leak out into the top of the head. 

[RJP]

That crack in the deck/head bolt area would most certainly be a cause for water in the oil.  As cited above the water will wick up the bolt and leak from the head of the bolt as there is no positive seal at the bolt and  cyl. head. Also consider this: the cooling system pressure is not static at whatever the cap says, say 14lbs. [But even at that it could be enough pressure to get passed the bolt head and the cyl. head.] As RPMs rise the water pump forces more coolant under higher pressure into those areas of the cooling system. I learned the hard way by not using the proper standpipe heater hose fitting in the intake manifold and burst 3 or 4 new heater cores in my 66 Galaxie/428 before I installed the proper fitting. How much pressure does it take to balloon and burst a brand new heater core? I would take a WAG and say 30-40 lbs. pressure. All the heater cores were fine until I spun the engine up to 5-5500 rpm...and then the heater core puked its contents all over the carpet.   

[Heo]

That crack in the deck/head bolt area would most certainly be a cause for water in the oil.  As cited above the water will wick up the bolt and leak from the head of the bolt as there is no positive seal at the bolt and  cyl. head. Also consider this: the cooling system pressure is not static at whatever the cap says, say 14lbs. [But even at that it could be enough pressure to get passed the bolt head and the cyl. head.] As RPMs rise the water pump forces more coolant under higher pressure into those areas of the cooling system. I learned the hard way by not using the proper standpipe heater hose fitting in the intake manifold and burst 3 or 4 new heater cores in my 66 Galaxie/428 before I installed the proper fitting. How much pressure does it take to balloon and burst a brand new heater core? I would take a WAG and say 30-40 lbs. pressure. All the heater cores were fine until I spun the engine up to 5-5500 rpm...and then the heater core puked its contents all over the carpet.

Did that in a 70 mustang one cold winternight the hot antifreeze  fogged up the cold widshield instatly, almost went of the road

[HvyFt4spd]

 There isn't much meat there but maybe a thinwall countersunk flange blind insert set in green loctite? Most guys seem to be okay with just thread sealer but something more permanent would be one less worry.