Rv8a2001

LS3 in kit car everything is fine ~7k miles never overheated, no heater, newer radiator, 2 small bypass holes in T-stat. One day wanted to check coolant in the morning. Lifted the level and it spewed 1 quart of water with loud bubbling/boiling sound. Only run distilled. Filled it back up, came out the next morning and it did the same thing. The engine has not been run in 48 hrs.
Now with plugs out and looking good, radiator cap off, I am watching water drip out of the overflow tube at 1 drop a second. Something is expanding in the cooling system
Runs, drives, cools great.

HELP!

B52bombardier1

Blown head gasket. Take a look at the following You Tube videos and buy yourself a "Block Check" test kit. The kit checks for the presence of combustion gases leaking into the coolant past a blown head gasket.


Rick

Rv8a2001

Tester says no combustion gases in system……

Ledzep

Check water pump flow or restriction in coolant flow. Are you sure it's not overheating? Could be airbound also. In a rare occurance, I found a jeep water pump impeller completely rusted and not pushing the coolant, not saying this is your case, but, I do agree from what you said, possible head gasket issue. Let us know what you found. Another thought, you could bypass the heater, maybe heater core has a blockage?