180 Degree Thermostat

[chri5k]

During a coolant change I swapped the stock 190 degree thermostat for a Motorad 180 degree unit. With the 190 the coolant temp was always around 194 and oil temp was 203 with out a load or my smaller trailer. I started towing a larger trailer and the temps shot up to 215 coolant and 230 oil. I was a bit concerned at the increase.

With the 180 unit the coolant temps are 179 to 181 and oil is also 179 to 181. What surprised me is that with the lower temp thermostat, the oil and coolant temps pretty much track each other. Whereas with the 190 thermostat the oil was always 9 - 10 degrees higher than coolant. Have not towed the big trailer yet but I am expecting I will see lower temps.

I live in Central Florida so I am more concerned with heat than cold.

 

[Iron Outlaw]

Interesting. I would like to do this too. My oil temp was up to 220 running 80+ to the beach this week.

 

[Iron Outlaw]

Where did you get it and how hard is it to change?

 

[chri5k]

The thermostat came from Amazon. It is a Motorad T426-180. Follow the upper radiator hose to the engine. It is in that large fitting held down by 3 bolts. There is a hear shield over it between it and the EGR cross-over pipe. You will need to remove the EGR cross-over pipe to get to it.

 

[Wild one]

Where did you get it and how hard is it to change?

Going by avatars he has a Cummins diesal while you have a 6.4 gas engine,they aren't the same T-stat.I'm not sure,but I don't think there is a 190 or 180 t-stat for the 6.4 trucks,i could be wrong,but I think the 6.4 uses an oddball thermostat and housing.Somebody will correct me if i'm wrong though.

 

[wgreggking]

Ive heard that its good to get your oil above the boiling point to remove water / condensation in oil. helps fight the build up of sludge. 215 oil and 230 coolant not horrible. I'm not a diesel guy though, As for the 6.4 t-stat assembly, I think the PCM opens and regulates operating temp.They had problems with them and are/were on back order for quite a while, no other options I believe.

 

[SouthTexan]

The Cummins oil cooler is on the other side of your oil filter in the block and is surrounded by coolant. So if you lower the temp of the coolant then you will lower the temp of the oil. Oil will generally remain within 10F from the coolant under light load conditions and up to 20F under heavy load. You are getting a more constant flow throughout the block with the 180F t-stat versus the 190F keeping the oil cooler temp more stable.

I don't think you will see that different of temps under heavy sustained load though. The only thing you might notice is that it may take longer to get to those higher temps(since your starting at a lower temp to begin with), but both t-stats are fully opened after 200F so there is no difference between the two past that point. If the a fully open 190F t-stat could not maintain 205F temps then neither will a fully open 180F t-stat.

In regards to keeping things cool in the heat, I would also recommend a Revmax thermal bypass valve for your trans. It removes the t-stat that is in the stock valve and has a larger port to the cooler with a lot less restriction. You will notice much lower temps unloaded and loaded, and you will also notice that it takes a lot longer for the temps to get hot.

 

[Gr8bawana]

I asked this same question on Cumins forum about installing a 180 t-stat in place of the 190 in my 2017. I live where the summer temps are regularly 110+.
Someone said that the colder the t-stat the less efficient the engine. Also that the 190 would keep the emissions system happy.
What do you think?

 

[SouthTexan]

I asked this same question on Cumins forum about installing a 180 t-stat in place of the 190 in my 2017. I live where the summer temps are regularly 110+.
Someone said that the lower the colder the t-stat the less efficient the engine. Also that the 190 would keep the emissions system happy.
What do you think?

That is pretty much true to an extent. A hotter diesel(to an extent) is more efficient. The only reason why I would install a lower temp t-stat is on a gaser so I can run more timing advance so I can make more power without fuel detonation. I probably would not run one on a diesel unless I was creating some major power.

What most people don't understand about t-stats is that it sets the minimum temp your engine will get to, not the max. The efficiency of the entire cooling system determines the max temp it will get under X load. Once fully opened, the t-stat has no bearing on temperature control.

 

[Iron Outlaw]

Going by avatars he has a Cummins diesal while you have a 6.4 gas engine,they aren't the same T-stat.I'm not sure,but I don't think there is a 190 or 180 t-stat for the 6.4 trucks,i could be wrong,but I think the 6.4 uses an oddball thermostat and housing.Somebody will correct me if i'm wrong though.

Thanks, I'm on mobile and it doesn't show avatars, and most posts on here are for 6.4 so I assumed that's what it was for.

So if pcm controls our thermostats we should technically be able to tune it cooler.

 

[Wild one]

Thanks, I'm on mobile and it doesn't show avatars, and most posts on here are for 6.4 so I assumed that's what it was for.

So if pcm controls our thermostats we should technically be able to tune it cooler.

I don't think the pcm actually controls the mechanical aspects of the thermostat,i think it has a sensor incorporated into the housing that sends info from the thermostat to the pcm,but doesn't actually control the opening or closing parameters of the thermostat itself.If you do a search here,you should be able to find out if they'res an aftermarket thermostat for your 6.4,as i'm not overly familiar with the 6.4's thermostat and whats available

 

[olyelr]

Thanks, I'm on mobile and it doesn't show avatars, and most posts on here are for 6.4 so I assumed that's what it was for.

Just an fyi, when on mobile if you rotate the screen horizontally that info will show up.

 

[wgreggking]

I don't think the pcm actually controls the mechanical aspects of the thermostat,i think it has a sensor incorporated into the housing that sends info from the thermostat to the pcm,but doesn't actually control the opening or closing parameters of the thermostat itself.If you do a search here,you should be able to find out if they'res an aftermarket thermostat for your 6.4,as i'm not overly familiar with the 6.4's thermostat and whats available

Cant tell fron this pic but its inline with the shaft 2017 6.4 It's definitely an assembly.

 

[Jimmy07]

During a coolant change I swapped the stock 190 degree thermostat for a Motorad 180 degree unit. With the 190 the coolant temp was always around 194 and oil temp was 203 with out a load or my smaller trailer. I started towing a larger trailer and the temps shot up to 215 coolant and 230 oil. I was a bit concerned at the increase.

With the 180 unit the coolant temps are 179 to 181 and oil is also 179 to 181. What surprised me is that with the lower temp thermostat, the oil and coolant temps pretty much track each other. Whereas with the 190 thermostat the oil was always 9 - 10 degrees higher than coolant. Have not towed the big trailer yet but I am expecting I will see lower temps.

I live in Central Florida so I am more concerned with heat than cold.

Coolant temps are perfectly normal for that thermostat. Pay no attention to the oil temps, as they are artificially generated by the pcm.

 

[chri5k]

I guess $20 for a real oil temp sensor was too much to put on a $50K truck.

 

[chri5k]

The Cummins oil cooler is on the other side of your oil filter in the block and is surrounded by coolant. So if you lower the temp of the coolant then you will lower the temp of the oil. Oil will generally remain within 10F from the coolant under light load conditions and up to 20F under heavy load. You are getting a more constant flow throughout the block with the 180F t-stat versus the 190F keeping the oil cooler temp more stable.

I don't think you will see that different of temps under heavy sustained load though. The only thing you might notice is that it may take longer to get to those higher temps(since your starting at a lower temp to begin with), but both t-stats are fully opened after 200F so there is no difference between the two past that point. If the a fully open 190F t-stat could not maintain 205F temps then neither will a fully open 180F t-stat.

In regards to keeping things cool in the heat, I would also recommend a Revmax thermal bypass valve for your trans. It removes the t-stat that is in the stock valve and has a larger port to the cooler with a lot less restriction. You will notice much lower temps unloaded and loaded, and you will also notice that it takes a lot longer for the temps to get hot.

I am towing the big trailer next week so I will report back on the temps.

 

[chri5k]

Well I towed the big trailer this week. The OAT's were 96. The coolant got to 206 - 208 so a slight reduction. Oil followed coolant within a couple of degrees but since it is not real data I ignored it. It looks like like I got 7 - 9 degree drop in coolant temperature. Don't know if the 180 opens a bit wider or is design just has less restriction but the temps were small bit lower.

I guess the current cooling system is doing all it can. Looks like the only way to get lower temps is to go with a Mashimoto all aluminum radiator. Those things are really a work of art. They increase radiator capacity 63% and surface are 41%. It is a shame they get buried in the engine bay.