So I've been trying to diagnose this problem. My brother said his 2004 Civic EX overheats, not all the time but has a couple times recently. The water pump, timing belt, PS belt and AC belts were all done recently. I was told to open the radiator cap when cold (some coolant spilled out immediately), then start the car and let it run. Bubbles came up pretty frequently and it pushed a decent amount of coolant out of the radiator. I let it run for about 20-30 minutes and bubbles were still coming. At the beginning kind of bigger gurgles, at the end more little bubbles but they never seemed to stop. It was parked on a slight incline as I was instructed to do. Could this be a bad radiator or fore sure is it the head gasket?
It could be the radiator. But first ask your brother if they changed the thermostat. That should have been done with the water pump. If they did not change that then that could be the problem.
never run a motor with the cap off, what can you tell from this, pressure test the cooling system, perform leak down test on cylinders, use a thermoniter to c/k the gauge reading,
White smoke from tailpipe? Head gasket.