Gurgling Noise

[Syndicated]

This question has nothing to do with buicks, however, I have come to trust the opinion of the members of this site so I've come here to ask...

I'm helping a friend of mine restore a 1968 Coupe DeVille with a 472ci V-8.
When he first bought the car, unbeknownst to everyone the T-stat was stuck shut, and when he went to start the car and let it run, it obviously overheated. When he shut it off, he heard a loud gurgling/bubling noise then about 5 mins later the lower rad hose exploded all over the place.
Since then I've replaced the thermostat, hose and refilled the cooling system and let the engine run up to temperature. It no longer overheats, but after shutting the engine off the gurgling/bubling noise is still there for about 10-15 minutes after shutting the engine off, then slowly goes away. I've eliminated air bubbles as the cause of this noise since I've bled the system many times of air.

My theory is that maybe the head gasket is blown and is allowing combustion gasses into the cooling system slowly until the pressure is vented. This is all the detail I can remember right now.

Any help would be appreciated!

Thanks!

Ben

[Bob]

If it's a blown head gasket, the water will also go the other way so you should have vapour out the exhaust and be loosing coolant.

If you are not experiencing these, it would almost sound like the water is boiling around the combustion chambers.

Where to go from there? Here's some thoughts...

Heat is not moving away from the combustion chambers when the engine is running in an efficient manner. Weak water pump? Corroded block?

Unrelated hint. Something I alway like to do is drill a 1/16" hole in the thermostat before installation to eliminate problems of air locking.