I have a 08 nitro that the cooling fan never comes in causing over heating I've replaced water pump radiator heater core because it was bad the relay seems fine power coming in and out but no fan on

If your 2004 Infiniti G35 is still overheating after replacing the thermostat and cooling sensor, there may be a few other issues that could be causing the problem:

1. Radiator blockage: The radiator may be blocked or clogged, preventing the coolant from flowing through it properly. This can cause the engine to overheat. To check for a blockage, visually inspect the radiator for any obstructions or debris, and flush the radiator to clear out any buildup.
2. Water pump failure: The water pump circulates the coolant through the engine and radiator. If the water pump fails, the coolant will not circulate properly, and the engine can overheat. Check the water pump for any signs of damage or wear, and replace it if necessary.
3. Fan clutch or electric fan failure: The fan clutch or electric fan is responsible for cooling the radiator when the car is idling or driving slowly. If the fan clutch or electric fan fails, the engine can overheat when the car is not moving. Check the fan clutch or electric fan for any signs of damage or wear, and replace it if necessary.
4. Head gasket failure: If the head gasket is blown, coolant can leak into the engine cylinders, causing overheating and other problems. Check the head gasket for any signs of damage or wear, and replace it if necessary.

As for the no heat issue, it's possible that the overheating has caused damage to the heater core or other components. It's also possible that there is air trapped in the cooling system, preventing the coolant from flowing properly through the heater core. Bleeding the cooling system may resolve the issue.

is water pump working--fans - and is the thermostat replaced correctly --radiator clean not clogged all these are some problems that can cause over heating

REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.MAKE SURE COOLANT NOT LOW.IF ALL IS GOOD CHECK FOR LEAKING WATER PUMP WEEP HOLE IF LEAKING REPLACE WATER PUMP.MAKE SURE COOLING FANS RUNNING.IF ENGINE RUNNING HOT WHILE SITTING LONG TRAFFIC LINE AND COOLANT NOT RUNNING.CHECK COOLANT FAN RELAYS AND FUSE.IF ALL IS GOOD HOT WIRE MAKE SURE COOLING FAN MOTOR GOOD IF COOLING FAN DONT RUN WHEN HOT WIRED FAN MOTOR BAD.IF FAN MOTOR OKAY AND FUSE RELAYS GOOD YOU HAVE FAULTY COOLING FAN WIRING.YOU COULD HAVE BAD ENGINE COOLANT SENSOR OR FAULT IN ECM CODE SCAN TO CHECK THEM BOTH.CHECK ENGINE OIL.LOOK LIKE MILK SHAKE YOU HAVE LEAKING HEAD GASKET.IF OIL LOOKS OKAY.YOUR ENGINE BLOCK, RADIATOR AND HEATER CORE NEED FLUSHING.

The most common overlook thing is you got a air pocket, so before you go spend your money turn Heather on full blast, open the radiator cap, car running look for air bubbles, takes patience cause you got to wait for the thermostat to open up, you must refill the coolant really really slow snail pace, some car have a bleeding valve others have two chamber on the overflow bottle,good luck, if that doesn't work change the thermostat first and if that doesn't work I'm afraid you may need to replace water pump. . water pump

SOUND LIKE HEAT CORES LEAKING ANTIFREEZE INSIDE DASH.

replace your radiator cap.

Over heat is caused by poor circulation of coolant. This problem can be: 1- The thermostat is not opening ( bad) causing coolant stagnant. 2- Water pump is bad, not circulate coolant. 3- Radiator is clogging up. It is full but water can not going through small clogging up tubes inside to have heat dissipated through the fines.
Since you also have no heat then I think the bad coolant causing the heater core clogged up also, unless the heater valve has a problem not allowing cooling flowing through the bypass hose to the heater core. Correct all 3 things above then you should be OK. Good luck.

your electric cooling fan is not switching on that is either 1. you fan is bad which you can test jumping a hot wire to the pos side of the fan if it works then exclude it. 2. your fan works on a ground system there is a coolant fan switch in the head that can cause no fans, and the last 3. nfan relay or fuse bad

You may either have a bad thermostat or a bad fan relay. If the fan is not turning on at all then the relay is bad. If there is not any heat coming through the heater then your heater core is plugged. That would also cause an overheating problem as well. To rule out a bad relay check to see if you are getting 12 volts at the fan connection. If not change relay.

Over heating can be caused by a faulty thermostat and or weak water pump and dirty radiator and old antifreeze or the radiator fan now working when at idle but should not over heat when driving. Service the cooling system if it has never been serviced before. Replace the thermostat, buy some radiator flush to clean out the radiator and heater core. Just follow the instruction and replace the antifreeze and make sure it's a 50/50 mix water/antifreeze. If you not sure how to mix it 50/50 you can buy them 50/50 premixed. Water boils at 100'C so you need antifreeze mixed with it but antifreeze does not have the same heat transfer as water so you cannot run 100% antifreeze cause it does not transfer heat fast enough and you over heat. Good luck and hope this helps. Keep me posted, Be glad to help, once you service the cooling system and your still over heating, then we look at the water pump.