2005 Ranger XL 2.3L 5sp 378,000 miles.

FTE Family

I bought this truck new and travel 180 miles daily for work and have recorder the fuel mileage over the years going from 32 to 27 mpg. This winter when it is below freezing the temperature gauge will drop well below the normal operation and close to the C on the bottom. I know this is just a reference gauge. When it is below freezing and the gauge drops the fuel mileage goes down 6 mpg to 21 mpg. Cooling system has been kept clean, it is full. When I get to destination and check under the hood the reservoir is full, the upper radiator hose and the motor are just slightly warm and not a lot of pressure on the hose. From using the search for Ranger and F150 I have put together that the thermostat may be failed open causing the computer to sense low temperature and go back into cool loop fuel management. No access to scanner. (Which scanner would you be able to view temp while driving?).
Normally I do all my repairs with the help of FTE but.
It appears something is controlling the thermostat. (If this is the computer is it getting information from the sensor) Do I have a bad sensor?
Is this project more than a simple part, should I take it to a shop to be serviced?
If not any input on probable failed part?
Thanks FTH
Happy Holidays to all.
Bob

 

I just went through a similar situation on my 97 2.3, I could drive it for miles and the temp gauge never moved, coolant hoses were relatively cool to the touch, and the heater would produce very little heat. Being that the hoses were cool to the touch, my first assumption was that the thermostat was stuck open. When I pulled out the old thermostat, sure enough, it was failed and stuck open. I bought a new one from orileys for $8, installed it and now the heater produces plenty of heat, and the temp gauge actually moves to normal operating range. One interesting thing I noticed, when I connect my scangage II, I can monitor the actual coolant temp, and the dash gauge in my pickup won't even begin to move until the temp reaches about 130°-140°F and tops out at 180°F. To make a short story long, I'd opt for replacing the thermostat first, based on your description of the cool hoses. Thermostats are mechanical, and don't need a computer to work, only heat. Your reduced fuel mileage could be a result of your engine operating below full operating temperature for a prolonged period of time. (just a guess).

 

Thanks for the reply.
I think part of my confusion is that I was issued a MOTORCRAFT RT1157 {#1S7G8575AJ, 1S7Z8575AG} 190 Degree Thermostat and it has large housing and a plug for wires and refers to motor control. After looking at the truck in the day light it looks like just a thermostat housing on the driver side of the motor with a radiator hose and one other hose not an oversize housing or wires for the motor control (?? Motor control??). So now I will exchange and go for the thermostat. Thinking the fuel issue is due to low operating temperature and shows more when below freezing.
Thanks FTE
Bob

 

The part# you listed is definitely a different housing set up than what I have. However, it looks like you should still be able to change out just the thermostat, which would probably be cheaper than replacing the entire housing. The smaller port I believe is the bypass/return line where the coolant temp is measured, and the sensor sends the info back to the computer.

 

Learning more every day looks like the wires are related to the Climate Control.
Thanks
Bob

 

I just did a google search on this & found a youtube video that shows how to test the electronic T-stat on an 03 2.3 which i believe works the same as yours.

2 wires connect to the stat housing and power a heated pin. The stat is a seperate item that fits over the heated pin.

To test remove the housing & the T-stat, connect 12 volts to the heater & if the pin gets hot the heater is working & i presume the seperate T-stat can be replaced.

If the pin stays cold the housing (ouch $159.00) needs replaced.

 

A 1997 2.3 will be a Lima engine, and a 2005 is a Duratec, so they are completely different engine families anyway.

The correct Motorcraft # for a 2005 should be RT1194. It comes with a composite/plastic housing with two necks, but shouldn't have any electronics. I think it is only '01-'03 that has the electrical connector, but I am not positive on that.

 

With your clues, ^+1 on putting the thermostat at the top of your suspect list. It's designed to fail in the open position & over cool the engine, which is better that it failing closed & overheating, so be sure to replace with a like design thermostat.
Have your Dealer run the Vin #, as you may be eligible for a no cost thermostat replacement!!!! A forum search before the call, will arm you with the program number. Let us know how it goes.

 

Update: I took the vin number to the Ford Dealer and the parts information showed no recall and the thermostat with a sensor which is different than what is on the truck. They were able to reorder one without the sensor. I explained to the service technician that I thought it was staying in cold loop, due to the temperature gauge being below C and that was why the fuel mileage was down by 6mpg. He thought that should trip the CEL, connected his laptop and identified no trouble codes or history. Using a hand held temperature tester he confirmed the inlet to the motor after warming up was only 33º, outside temperature was in the twenties. So after installing a new thermostat and housing, coolant flush and new antifreeze the operating temperature returned to normal and the engine is running smooth.
Thanks FTE and all for the help.
Bob

 

Good find, fix & feedback on your over cooling trouble shoot & to hear all now seems well. I agree that the computer should have been aggravated enough to have lit the CEL.

 

pawpaw one of the thing I have learned from you is the importance of reporting back it really brings the FTE site to a new level when you can follow a repair from diagnosis to repair to return to normal service and all the investigating along the way.
Thanks

 

Please let us know if you notice any improvement on your fuel mileage.

 

Having a number of tanks of fuel ran than through the fuel mileage is back up to 26.7 MPG. This is good because I am back to two days’ round trip with no fuel light coming on.
Thanks to all at FTE for the help.
Bob.

 

OK, good to hear replacing the thermostat seems to have put the fix on your mpg drop & thanks for closing out your thread.

 

I had a similar issue on my 2002 w/4.0L last year. Gas mileage way down from what I was used to. Scan tool showed ECT was running lower than some data logs I had done years ago. Long story short, I did a bunch of stuff that didn't make a difference(including the thermostat), I finally replaced the ECT transducer in the summer and gas mileage went back to normal. Never had a CEL or any codes and the difference between the old sender and new was only about 10F.

Edit - I should add in addition to the new ECT sensor I found the wiring from the connector was bad and replaced the connector and 6" of wiring.