I have a 2002 Nissan ultima, the heat didn't work when I bought it, they replaced the thermostat, it worked briefly, then stopped the mechanic said it was the radiator cap, he said he fixed it, now I gave no heat again and while sitting my temp gauge is going to hot

SOURCE: Outback 1997 was overheating. Temperature

sounds like heater problem.not enough flow down to waterpump.
solution cut heater hoses and add to t junctions and join bypass so water flows through heater and through bypass straight to waterpump.

SOURCE: 99 seville is overheating. temp

My retired uncle has a 97 cadillac deville sts that runs well but after a short distance or time idling begins to overheat. He has replaced the water pump, thermostat and had the radiator and head gasket checked. Unfortunately he lives in a rural area and there is no local cadillac dealership for diagnostic repairs.

Steve Allison

• 5569 Answers
• Posted on May 26, 2009

SOURCE: radiator fan not working replaced relay,temp

You didn’t mention replacing the temperature sensor located on the block in the path of the ‘cooled’ coolant.
I can’t tell you any closer where to look for it since you didn’t specify which engine you have.
This device is a solid state item called a thermistor.
With the air temperature around 77 degrees F and a 'cold' engine, it should measure about 10,000 Ohms and hot, around 1,200 Ohms while disconnected from its mating connector.
With the ignition on, and the connector disconnected from the sensor, you should measure about 5 volts coming from the ECU.
If this has failed, the ECU is not getting the right info back from the sensor and doesn’t know if the fan is needed or not.
 

SOURCE: 2002 dodge 1500 Changed radiator, thermostat, and hoses. No heat

Why was radiator replaced?Did it have heat before ? If it was plugged, the heater core may also be plugged. Try flushing it with a water hose in both directions. I dont know why the botton radiator hose would be cold, the radiator should be a uniform temp and the air coming through the radiator should be HOT, when the engine is at operating temp. What condition was the old coolant? if it was rusty, the water pump may have lower flow than normal.

SOURCE: 2002 Dodge Ram 1500 4.7L- Started over heating a

As long as you reseached the problem and have confirmed that head gasket is not leaking. Blowing out coolant, coolant reservoir appears milky or oily. The next step is to replace the radiator.

These are single core cheapy radiators that Dodge instaled on the 2nd generation Rams with the 4.7 L engines. Cost to purchase a new radiator from onlines stores is about $120.00 . Flush the engine and heater core before reconnecting new radiator. See my other detailed post regarding the overheating problem with 2004 models too.