04 Honda Civic. New radiator put in last year. New water pump put in last week. Honda has been overheating randomly for about two months now. No smoke. When I pop the hood, there is water splashed everywhere. It also will not take much water in the radiator. I don't think there is a leak. Mechanic did a pressure test last week. He is puzzled. Thermometer has been replaced.
It seems I can feel a slight hiccup just before dial starts moving to the H. Almost like car is switching gears. Dial rises quite fast. I pull over. Pop hood. And see what appears like a huge splash of water. I let engine cool, put an ounce or two of water in, start up and car is fine until a few weeks later. Then it overheats again. Any ideas?!

 

I was having the same problem so i did the following things and it worked.

1. Get your thermostat changed and get your radiator flushed. These are both routine maintenance and you should be able to get them both done for less than 100 bucks, if that.

2. Make sure you have enough coolant in your system including the overflow bottle. Make sure you have the right blend for your car - usually 50% coolant, 50% water.