What Thermostat temp is best for Dodge Ram/24v Cummins?  Just wondering if I would get better fuel mileage with the 190* thermostat.

What temp do you have and mileage.

Thanks, Kerley

 

When I bought my truck it had a 180 in it. One of the first things I did was replace it with a 190. When I worked for the Bakery we changed all of our 6bt's and 4bt's to 190. We did it mainly because they don't have much of a heater and its like riding around in a freezer in the winter.

Like yesterday I made a run to Ontario, OR for some personal stuff and with my winter front still in and outside air temperatures in the 60's I was starting to pull a nice 19 MPG @ 65 MPH. Coolant was ranging in the 195-197*F.

I bought a 190 Stant at Advance last January, and it worked well until the last week or so (of course a month out of 1 year warranty), So I stopped at NAPA today and picked up a part #375-190.   I got home and swapped them out, and realized they were identical. Soooo, I look on the NAPA box and lo and behold- Stant Corporation.

I'll see how this one does from cold start tomorrow. 

So how about a Cummins part # for the 200 degree thermostat?  Does anyone have that information?

Can someone explain what exactly you guys are meaning when you say 180/190 etc thermostat? Are we talking just the gauge itself in dash? I know my gauge RARELY if ever gets off the very bottom tic mark on the gauge itself. I think that makes it 165 degrees-ish and it takes quite a while for me to get heat in the cab. Although after putting in my amsoil air filter with no heat guard I've noticed it does warm up a little faster.

Thermostats for our trucks are designed to keep the temperature at 190*, that is what is meant by the 190*.  Some have played around with other thermostats that operate around 200*.  are you saying that your engine doesn't get warmer than 165*? Ever?  You may have a thermostats that isn't working correctly.

Edited February 25, 201510 yr by Hawkez

As long as I can remember the temp has rarely shown over 165* on the gauge. Just recently it's occasionally started jumping up to maybe 175ish but usually only under harder acceleration up a decent hill, but then right back down. I'm going to swing by and pick up a new thermostat. I'm sure I'll loose some coolant in the swap. Does anyone recommend a certain type of coolant or does any ethylene glycol-based coolant work, especially for basically a top off?

I put the green Oreilly's brand in my truck. 

As long as I can remember the temp has rarely shown over 165* on the gauge. Just recently it's occasionally started jumping up to maybe 175ish but usually only under harder acceleration up a decent hill, but then right back down. I'm going to swing by and pick up a new thermostat. I'm sure I'll loose some coolant in the swap. Does anyone recommend a certain type of coolant or does any ethylene glycol-based coolant work, especially for basically a top off?

Your mileage must be horrendous. I replaced mine with a stant then a NAPA, and jokes on me they are the same build.  Hope you get that addressed soon. 

Your mileage must be horrendous. I replaced mine with a stant then a NAPA, and jokes on me they are the same build.  Hope you get that addressed soon.

I think I actually get pretty decent mileage! About 14-15 around town and just recently did a 1000 mile trip from central CA to northern WA and averaged about 22-23mpg. Granted that was off the trucks calculations but I've never felt my mpg's were sub par.

I do have the Napa thermostat ready to go into the truck in the morning. I wanted to do it tonight but the coolant was too hot! All I have for coolant is some cheap-o 50/50 pre-mix though. I'll probabaly do a full system flush in the near future. I don't like mixing different things! Haha

*UPDATE*

 

I replaced my thermostat this morning. The gasket had practically melted, so needless to say, it wasn't easy getting it out of there. But I got it swapped out with the shiny new one from Napa. I took an extra long drive to work this morning and saw my temps rise to around 180ish so I think I'm good to go!

 

In the process of all this, I was following directions from HERE and when I tired to drain my coolant from the drain hole as shown, I couldn't get anything to drain! I ended up having to remove the radiator hose from the thermostat housing and using an old milk carton to catch as much excess coolant as I could. After I had the housing off and old thermostat out I tried the radiator drain again and still nothing. Is this cause for concern?

 

 

After I had the housing off and old thermostat out I tried the radiator drain again and still nothing. Is this cause for concern?

The drain-cock for the radiator will only turn a half turn or so and then you need to pull it outward.  It will not come all the way out, but that is what will open the drain and allow the fluid to leave.  Were you pulling it out or just turning it?

You might have crud blocking the drain valve, I did one time and had to pull the whole drain valve out.

The drain-cock for the radiator will only turn a half turn or so and then you need to pull it outward.  It will not come all the way out, but that is what will open the drain and allow the fluid to leave.  Were you pulling it out or just turning it?

 

  I was definitely JUST turning it. Now that I look back through those instructions, it's completely obvious in that 5th pic that it gets a 1/2 turn and then PULLED OUT! Jeeeeez!

 

Thanks guys!

Edited February 25, 201510 yr by notlimah

Glad to hear you are warming up! Back to the single digits here again tomorrow. 

I run a 200f tstat for a 6.7l and the truck runs better warmer with it.

It is nice when it is cold out. I can see 170f with the heater on and not on max ac

I run a 200f tstat for a 6.7l and the truck runs better warmer with it.

It is nice when it is cold out. I can see 170f with the heater on and not on max ac

 

By chance, do you have the Cummins Part # for that thermostat?