I have a 1988 honda crx with the factory engine, my problem is after about 4 days of driving the car it will start to overheat. I then put more water in and then drive it again for another 4 days and it again starts to overheat. There is No puddles under the car, it doesnt smoke at all, the fans kick in, it has a new radiator, new cap, and thermostat.

 

you may have a blown head gasket if your adding water all the time, you may also want to try to bleed the sytem as well, but chances are blown gasket, do a leakdown/compression test.

 

Sometimes with water leaks you might not allways notice a small one. The water is at a high temp and evaporates easy.