Can a head gasket do this?

[oldfox]

Hi, I have a mostly stock 5.0 and I'm running a little boost 10lb max and this
sounds nuts but here goes,, When I hit about 8lb of boost the water blows
out of the radiator--So hard you got to see it to believe it--
But no water in the oil and no miss at an idle runs smooth and no problem
until I boost. And I would swear I can hear compressed air rushing out of
some where is it possible for the compression to squeak past a head gasket only when the compression is raised? The car runs fine when not boosting.
I know I'm picking up extra pressure in the cooling system and head gasket
is about I can think of. Am I missing something here?
Possible? Ever hear of this?

 

[Fordfanatic89]

I don't get why you wouldn't have the additional issues that go with a bad headgasket ie: coolant getting into the combustion chamber. I guess if the head gasket isn't completely blown. The pressure is more against the gasket when you're forcing air into the chamber vs. the coolant pressure pushing it into the combustion chamber. So no white/coolant smoke from the exhaust?

I am pretty sure I have seen this on Ford turbo diesels but generally it leaks both ways, into the chamber and into the cooling system.

 

[Mustang5L5]

Molecules of air are smaller than water. That leak would have to be sized "just" right to allow 1-way travel of air and not water. Very odd if that happened.

 

[Rick 91GT]

Lower intakes will lift as well causing similar issues. Check the tq on the lower intake, I stud most lower intakes on boosted setups that leave my shop.

 

[4rdnut]

sounds like your running straight water with a worn out radiator cap if its pouring out of the radiator

 

[Rick 91GT]

What pound cap is on the rad?

 

[oldfox]

What pound cap is on the rad?

I'm running a 16lb cap and it's new.

 

[oldfox]

I found it,
I switched the pulleys around to increase the boost and gave it a good thrashing. I now have a dead miss and #4 is dead. I pulled the plug and I have water in the cylinder and white steam coming out the exhaust.
I guess that the gasket was just starting to go bad and the extreme pressure the cylinder produces while boosting was enough to escape but the 16 lb pressure in the cooling system wasn't enough to get around the flaw in the Gasket. At least now I know what the problem is.

 

[VibrantRedGT]

Been there and done that. I could change head gaskets in just a few hours with my Vortech S-Trim installed. I got greedy and changed to a small blower pulley, bad idea. Not once but twice blew the heads off the block (see 14+ psi). The third time was a charm and broke a ring in #5 & #8. Then I sold the Vortech to fund the 347.

Do yourself a favor. Change headgaskets, don't get greedy and most important get it tuned then leave it alone.