how do i bleed a car radiator?

Hi, Dennis,
Presumably you've done something to the cooling system to allow air in...perhaps drained water out to put antifreeze in or changed the thermostat, maybe. Sometimes you'll get away with it, sometimes, as you've done, managed to get an airlock in the system. Air in the system will always find its way to the highest point. First of all, find where that is. Maybe it's the filler bottle or expansion chamber. Run the engine up to its noraml operating temperature, as this will tend to forsce the air to the high point. Then, very, very, very carefully, with a rag over the screw cap, unscrew the cap very slowly. If you do it too fast, very hot water tends to spurt out and do nasty things to you. You should a hiss as the air's forced out. Now, try the heater. This may have done. If not, you've got to loosen a hose. Find the highest hose connection on the engine (remeber the air will always go the highest point. With the engine to normal temperature, slacken the clip holding the pipe then very, very gently ease the hose away until water floods out freely, then remake the connection and tighten the clip. It helps to loosen the connection when the engine's cold actually, to make it easy to move when it's hot. This should have got rid of all the air now. Make sure all the connections on the hoses are tight if you've put antifreeze in, as antifreeze will find a leak where water won't. But do be very careful, as the water in the cooling system at normal operating temperature is nearly boiling....I've learned the hard way!!
Best of luck and stay warm!!

Denis (CareAid Mobile Mechanic)

Denis Langley
November 2007