Hey guys this forum is awesome! I am a die hard Dakota owner who spends way to much time fixing and replacing stuff that isnt broke. My question is I just put in a new thermostat and Im pretty sure its running too cool, My mpgs have dropped and its so low it worrys me with winter around the corner. I will post a pic when I am off work but it looks like its running at 165 - 170. I am pretty sure i just got a bad one that opens too soon but what do you guys think

 

It's normal. The temp gauge will read just a little bit lower due to the lower temp input from the thermostat. My truck did the same thing when I put in a 180 tstat, the gauge is slightly lower at operating temperature. Stock tstat is 195, so your coolant temp with a 180 probably is not that much lower. Dodge engineers did a study some years ago and found that the Magnum engines actually make better power and run more efficiently at 182 degrees, but they had to use a 195 to meet the Federal Emissions guidelines. I don't know where you live but I have had no problems at all in winter resulting ftrom my 180 tstat, but it does not get that cold here in Florida. My heater works fine, truck runs great and has never overheated.

The lower MPG is also a characteristic of the lower t-stat. With a 180 degree t-stat the PCM thinks the engine is not up to full operating temperature so it richens the air-fuel mix and advances the timing just a little. Both of those will reduce your MPG. The trade-off is increased performance from the advanced timing and richer air-fuel mix, and it can help reduce preignition ping. On my truck, a 180 tstat and Autolite 3923 spark plugs eliminated the ping completely.

Jimmy

 

Awesome thanks for the info dude, i have switched from the 195 back to the 180 several times and it just looks lower than it did before, and im in minnesota so it can be a little chilly out in jan! This pic was taken after a 30 mile drive all highway

 

Yep that's about where my temp gauge sits too. My gauge is different from yours, it has no numbers on the gauge face but I guess the travel on the needles is about the same and the gauges each indicate about the same temperature. Unless your heater is not hot enough for you I would say don't worry about it.

Jimmy

 

Yeah it has just about eliminated all pinging unless i im in the wrong gear like 4th instead of third and put the pedal to the metal,