When you say it starts to run on one cylinder when the cooling system cuts in, do you mean the fan starts or it just begins to get up to temperature? If water is getting into the front cylinder it can do so only really from two places. Head gasket or a cracked water jacket. If the brick hit the exhaust hard enough to dent it, maybe it carried enough energy through the studs to damage the cylinder???? You really won't know until the front cylinder is off. |