Condensed version:
Thought a customer's car had a blown head gasket, pulled the head off and noticed that the intake runner had coolant puddled up in it. Looked at head gasket.. couldn't see where it had blown. I'm thinking the head has broken thru to a water jacket, but I can't find a hole yet (maybe it's really small). I'm going to have the head pressure tested today to make sure. But is there ANY way coolant could have puddled in the intake runner from a blown head gasket? I can't see how it could be anything but a water jacket leaking into the runner. The heads are ported and have about 1000 miles on them. Where are the "thin places" to look for a hole at?

 

My guess would definatly be that someone ported too much.

 

Thats a hellacious porting job, maybe a little over zealous. Rocker bolts not sealing typical, but you bust through the jacket, ouch. With the design of the LSx I am sure the only way to get water in there would be over porting. Post up pics of your finding if you can.

 

I've been doing some research and it seems like the area right behind the valve guide is the "thin" spot on the castings. I'm going to wait on the results of the pressure test and go from there.

 

And it's only in 1 runner, right? (thinking maybe it could be coming from the TB if they haven't done the coolant bypass, but with ported heads I would guess they have......)

 

Gomer, I have blasted through a few LS1 heads to check tolerances and depending on how agressive the port job, you can actually break through in a few spots. The most notorious being the swirl ramp close to the runner wall, mid way up. Other common spots include the "sweep wall" in the intake bowl, on the right side if looking down through the CC, this is where the majority of porters try to max out for gains. You can also break the upper left wall straight accross from the valve guide. The roof by the valve guide actually has a decent amount of meat and there isnt a ton of gain to be had there anyway.

Brandon