coolant leak problem update

[Jeff Taylor <jbtaylor@domain.elided>]

My initial thought, or at least my thought yesterday, was a crack inside the
intake manifold. So I went out and got a 4-bbl intake, I kinda wanted one
anyway. 

I bolted on the new intake, held my breath... and got the same leak. I then
used a piece  of duct tape to block the exhaust crossover port on the leaky
head and bolted the IM back down... A-HA! It still leaks. So I pulled the head
(again) and blocked the crossover hole with duct tape. I set the head on edge
so the exhaust ports are facing up. When I put water into the #3 exhaust port.
it comes out the coolant port!

I guess I have a cracked head. I also guess I'll be going back to the machine
shop on Monday to see what they can do to make this right. Hopefully they can
find the crack this time.

Does it seem possible the crack was there all along, maybe plugged with years
of gunk, and when the machine shop cleaned the heads they dislodged the plug,
and then missed the crack when magnafluxing (or didn't actually check it for
cracks)? Or is it more likely that they cracked something while rebuilding the
heads? Or could I have done it while torqueing down the heads? I did use the
FSM pattern and used 3 or 4 torque steps.

Jeff Taylor
(relieved to have found the problem, not so happy the head is cracked)


John A. Landry wrote:

> Aside from some massive crack in the head, there shouldn't be any way that
> coolant can get into the exhaust port *from the head* itself.  Rather, I have
> a hunch that the problem you're encountering is with the intake manifold.  I
> know you said it didn't look like coolant had been in the intake manifold, but
> it just seems too strong of a possibility that something is wrong there.  I'd
> examine the intake manifold very carefully for internal rust or corrosion
> holes.  I'm thinking maybe coolant is passing between passageways in the
> intake manifold when it's not supposed to.  You could block off various
> passageways with duct tape and use low pressure compressed air to check the
> integrity of the intake manifold.