You should have a cooling system pressure test performed when the engine is cold, and if there is no indication, idle the engine until it warms, then give it some acceleration. You might be able to loan-a-tool from Auto Zone. There must be some sort of leak.bmx-dad said:I have a 96 suburban 5.7 and its bubbling thru the over flow bottle just on excelleration, i was told it might have a cracked head or block or gasket leak? it doesnt seem to be blowing much smoke yet? the engine light isnt on eather.