I'm not too please with this, but it is interesting. My 05 350 always ran somewhere in the bottom third of the temperature gauge. One day it registered in the upper third. Hmm, my first thought was the thermostat failed. Replaced it with an O'Reily part. It didn't do much better, I thought. So I got a spendy Gates Thermostat and slide that in there. About the same. I began looking at other things, and found the fans weren't turning on with the air conditioning. I checked all the relay's / fuses etc., they were getting power. So I jerked them out, put in a new set. They have power and both run strong with the air-conditioning turned on, however the car still heats up, say to the halfway mark. I don't really like that. When I fix something, I kinda like it to go back to normal. I'm wondering if there isn't a computer code that is supposed to turn on, say, one fan when the engine reaches a certain operating temperature. I don't know how to check that, but it makes sense to me. Any suggestions?

 

Well, after about the fifth burp, squeezing hoses and removing the plug in the heater core line back by the fire wall, she seems a bit better. Running n the lower 35 percent of the gauge. But it's cool weather. In mid-summer, that would be over heating. I know that old cars had an actual valve that turned on the water flow to the heater core, but it's hard to believe in 2005 the Japanese would do this. Turning on the heater in the car should only start a fan, open an air flow door. Anyone have a better idea of the heater core water flow?