My car is 2001 maxima changed thermostat was acting fine got on highway got hot , flushed radiator twice and changed fluid got on highway to test 10 min out fine started to get hot now heater working great but not drawing heat off engine there's no water in oil so the pump according to everyone is fine so what can be the issue . It's killing I've tried everything except water pump and timing I'm missing out on precious time with my kids tell me you have a simple and quick solution