P0128, 2004 3.0

[flyin-lowe]

My son's truck, 120K miles. Light came on tonight and reads P0128. From what I am reading most likely cause is thermostat. I plan to replace that in the morning. Watching YT videos seems really straight forward. Couple questions though, I looked on Oreilly's website tonight to make sure they had them in stock, they show several different temperature's. Which one do I need? In Indiana if that makes a difference. What would the stock thermostat be as far as the temp goes? Also, I assume on this year Ranger the standard coolant is fine if I need to top it off? Lastly, will I loose much (if any) coolant if it's been parked for a while? Didn't know if I need to drain any or since that hose is high, should it not be holding anything if it has not been running?

 

[flyin-lowe]

I went out this morning to check the coolant levels and I noticed as I looked around there was some moisture around the thermostat housing. I went ahead and bought a new housing (aluminum) and thermostat. I am 90% certain the thermostat I took out was in upside down but wasn't really paying attention because as I pulled the housing off I was trying to get my drip pan kicked into the right position, but the way I pulled it out and had it in my hand i "think" it was upside down. Am I dreaming, or is it possible it could have been upside down since I have owned it that past year? Got the new housing, stat, and gasket installed and a 50 mile test drive with no CEL so all appears to be well. The temp gauge went to right at straight up and down in the dash and stayed there.

 

[SenorNoob]

The previous owners' ability to do stupid thing is unmatched...

 

[flyin-lowe]

Would it run and not have major issues if it was in upside down? The only “issue” I noticed was last year when it was really cold a couple days the temps would drop at interstate speeds and then once we slowed down they would go back to normal. This only happened one day and it was close to zero out so I thought that might have been why…

 

[SenorNoob]

I would think it would open later upside down. IF it could open at all. Obviously did thou or you'd have an overheated engine.

 

[flyin-lowe]

Like I said, I'm not 100 % sure it was in upside down. I pulled it out and as soon as I did I started using my foot to move my catch can around. But the way I was holding it in my hand it would have been upside down. I don't feel like I spun it around in my fingers. I didn't know if it would ever even open if it was upside down. Possible it was in right, just have a feeling it wasn't.