12v owners. I installed a Stant 13479 thermostat over the weekend. NO more wild 50* temp. swings from the old thermostat. Just nice mild 5-10* swing on open and closed. Got the idea from ghostman over on the other forum. Very very happy with the results. Truck actually made temp. on my way to work this morning in the 37* cold. It would have been barely off the 140* mark with the old tstat.

On 1/3/2018 at 9:27 AM, jlbayes said:

 

I had to clean out my housing to get the stat in. I am watching the cluster vs. your scan gauge as well. I get one huge temp. swing when the stat initially opens. It is slow to react at first. I also have a small air pocket in the heater core. Gurgles on startup.

Mine would not fit at all. I had to trim off almost an 1/8" all the way around to get it in with the o ring. Of course it is 12v t stat in 24v engine.

 

Ahhh ok. That would be why then lol

Since there is all the talk about 200° thermostat's I'll chime in. 

 

Dodge/Ram went to a 200° thermostat with the MY10 trucks. This was done to help increase fuel mileage,  and presumably reduce emissions/regens. 

 

The hotter the engine the more efficient a diesel engine should be. For this reason I always said that I would switch to a 200° thermostat in my truck once we had fan control with UDC. 

 

Well we have UDC fan control and I will not be swapping out to a 200° thermostat. Dodge/Ram only ran the 200° thermostat for 3 years and that made me wonder why, especially since it should yield a more efficient truck. 

 

So I started doing a little research and the only thing I can come up with is that while the motor might be slightly more efficient the oil temps got too high while towing and they were seeing oil issues related to heat. There is nothing definitive thou. Oddly enough when the trucks went back to a 190° thermostat they also got an oil temp gauge (thou I cannot determine if they are real or fake). The newer trucks also have a much more aggressive fan schedule than the older ones, that keeps the coolant and oil temps lower. 

 

On a 2nd gen, or a non custom tuned 3rd gen, you won't have the ability to change the fans lockup temp and a 200° thermostat will cause the fan to operate more even thou the temps are in the normal range for a hotter thermostat. 

 

So that's my 0.02. 

 

 

Edited January 9, 20187 yr by AH64ID

I'll monitor my fan lockup this summer, but I was under the impression the fan wouldn't lock up until a temperature quite higher than 200°F.

38 minutes ago, kzimmer said:

I'll monitor my fan lockup this summer, but I was under the impression the fan wouldn't lock up until a temperature quite higher than 200°F.

 

A 200° thermostat cracks at 200° but it’s not fully open until around 215-217° which, IIRC, is well above the fan temp. 

 

For reference a 180° thermostat is fully open at 198° and had a max allowable (based on heat rejection data) of 212°

 

The 190° is fully open at 207° and has a max allowable of 225°. 

Fair enough. Don't forget, however, that the 2nd gen fan clutch is not electronically controlled. I don't know if that's really an argument, but the temp of the fan clutch is not necessarily the same as the coolant temp. 

 

I had the same thoughts that you have posted however. I did quite a bit of reading about it and decided the fan shouldn't run any more unless I have other problems and the thermostat can't keep up. I'm excited to find out.

A hotter thermostat should yield a hotter enigine bay and radiator for the same load, both of those will have an effect on fan operation for a fan clutch designed around a cooler thermostat, which would make it cycle more even with everything in proper working order. 

 

I’m certainly interested in hearing about more data when the temps warm up. 

On 12/28/2017 at 12:50 PM, jlbayes said:

Tech Tip Description:   Important! There has been an application change to the Cummins turbo diesel thermostat. When replacing a thermostat confirm the correct replacement is choosen.

2010, 2011, and 2012 RAM Trucks 2500/3500/4500/5500 engine coolant operating temperature has been increased to 200 degrees requiring thermostat 68067109AA.

2009, 2013, and 2014 RAM Trucks 2500/3500/4500/5500 engine coolant operating temperature is 190 degrees requiring thermostat 68005464AA.

These thermostats are not interchangeable and doing so will result in reduced engine performance.

 

16 hours ago, AH64ID said:

Dodge/Ram went to a 200° thermostat with the MY10 trucks. This was done to help increase fuel mileage,  and presumably reduce emissions/regens.

 

:thumbsup:

Cummins part number for a 200° thermostat is 5292724.

 

More fuel in the anti-200° thermostat fire is that Cummins doesn't use it on any of the non-Dodge/Ram ISB/QSB motors. 

 

Cummins preferred thermostats are 180° for non-EGR and 190° for EGR. 

 

I'll be putting an oil temp gauge in this summer and will drop to a 180° if the oil gets hotter than it should.. thou I don't think it will. 

4 minutes ago, AH64ID said:

I'll be putting an oil temp gauge in this summer

 

From what I remember on the 24V truck the oil temp follows fairly close to coolant temperatures. Can't vouch for CR engines.

2 minutes ago, Mopar1973Man said:

 

From what I remember on the 24V truck the oil temp follows fairly close to coolant temperatures. Can't vouch for CR engines.

 

It's the same, and should be similar under every day driving. When making sustained power, i.e. towing, the oil temps will get hotter than coolant temps as the oil has direct contact with pistons and the oil cooler is the coolant. 

2 minutes ago, Mopar1973Man said:

 

From what I remember on the 24V truck the oil temp follows fairly close to coolant temperatures. Can't vouch for CR engines.

It does with in 10 degrees i believe, I had my trany temp guage plugged in oil line for a while and it was very similar to coolant.

1 minute ago, AH64ID said:

and the oil cooler is the coolant. 

Makes sense, that's why oil cooler gets cooled with antifreeze. 

The 4th gen trucks with oil temp show about a +20° oil temp, but I still haven't heard if the sensor is real or fake. 

 

I've looked and can't find a part number for a oil temp sensor and the pressure switch part number hasn't changed since 2007 so it's wasn't incorporated into that. 

Edited January 10, 20187 yr by AH64ID

The 3rd gens were a switch. Some late 2nd gens too.

3 minutes ago, jlbayes said:

The 3rd gens were a switch. Some late 2nd gens too.

 

Correct, all 3rd and 4th gen's use the same switch. 

 

2nd gens all have pressure senders; however, the ECM has been reprogrammed to treat it like a switch instead of a sender. 

Not all. As long as you never had any reflashes done the oil pressure is still a gauge. Mine still shows true pressure. I know that your right and if thee ECM been flash to the newest version then yes the gauge is switch. 

57 minutes ago, Mopar1973Man said:

Not all. As long as you never had any reflashes done the oil pressure is still a gauge. Mine still shows true pressure. I know that your right and if thee ECM been flash to the newest version then yes the gauge is switch. 

 

Right, generally only if it's been reprogrammed. 

 

I thought that by 2002 they were all "switches" from the factory. 

Edited January 10, 20187 yr by AH64ID

I thought the 02s were all switches also based on what I have read here.. 

I think there was a TSB to flash a change to the trucks to make the oil pressure gauge read more like an idiot light, "good" or "bad". Because people complained that pressures would appear to be high or low in certain circumstances (high vs low temp, low vs high rpm). Not the stupidest thing I've heard this week but it's in the top 5.

Yes there was a TSB that converted it from a sender to a switch. 

 

@Mopar1973Man have you ever had a smarty on your truck?