Some of you 3.0 savy dudes on here please help me out. I got a 97 Ranger XLT 3.0 automatic I’m having a little issue with My temperature gage first thing I want to do is replace the sending unit. Can anyone tell me which sending unit goes to the gauge & which one goes to the ECM. Is the one on the thermostat housing or the one that screws into the manifold going to the gauge? they both have similar looking plugs with two wires. Rock Auto doesn’t show any difference except the color of the plugs one black one grey. Do they both use the same sensor?
Thanks, Larry

ps: The reason I’m doing this is because once in a while after a long drive when I shut it off it will boil a little water back into the tank. The gauge is reading about halfway with my laser temperature gun. showing the top radiator hose and thermostat housing to be about 190°. The bottom radiator hose was about 164°, but I put my thermometer in the tank water and it Pegged at 220°. I have replaced the fan clutch the radiator with a dual core three different thermostats and new hoses.
also pressure tested radiator/engine with engine hot held 16 pounds for over 10 minutes and it passes the glove test. Completely flushed with new coolant and flushed heater core .The only thing I haven’t replaced is the water pump. You can idle the motor for 30 minutes with the air conditioner on and 90° outside. never overheats never overheats on the road either. Even pulling a trailer with 1000 pounds in it. I’m stumped!!!

 

Notice the difference in the tip

Sender
https://www.rockauto.com/en/moreinfo...138159&jsn=977

Sensor
https://www.rockauto.com/en/moreinfo...sn=975&jsn=975

 

You mean one is cylinder Derico and the other is conical so which one is which?

 

Red/white wire is on the SENDER, for dash temp gauge
grey/red wire is on the sensor

 

Thanks Ron I knew you were in there somewhere...
Larry

 

Ron:
One more question the red and white wire you referring to is that the trigger wire to the Grage and the other wire is the ground? Do I have that right?

 

Yes, red/white wire would run to the gauge, in the past a SENDER was always just the 1 wire and used its threads as the ground, in later years a separate ground wire was added as more "plastic" parts were added to engines, lol, i.e. the 4.0l SOHC has plastic thermostat housing with sender on top, so a no ground housing, needs 2 wires
2nd Sender wire often matched signal wire, in striping, so black with white stripe in this case

Sensors, for computer use, always have at least 2 wires

 

Man you are the Ranger knowledge base thanks again Ron.
Larry