My Thermostat has stuck Open

[Donpd]

My thermostat has stuck open.

The questions I have are should I get the 180° or the 190° thermostat? Where should I purchase the replacement from a dealer, Geno's Garage or a parts store? I have a 2005 truck.

 

[p-Bar]

Stant should be good still. You better replace as spec'd as they run these hotter today to meet emissions

 

[6speed]

I put a 180 in mine. I live in the south and in IMHO it gives me a little wiggle room to play with on temp. It will still get up to 205 when in a hard pull, but cools right back down. I got mine from Geno's.

 

[ata]

My thermostat has stuck open.
The questions I have are should I get the 180° or the 190° thermostat? Where should I purchase the replacement from a dealer, Geno's Garage or a parts store? I have a 2005 truck.

Go with a Cummin's or Geno'o which is a Cummin's. I would put in a 180 if it was my truck.

 

[BDaugherty]

The same thing happened to my '01. I found a 190 deg made in USA Stant at the local parts store. It worked fine, but I notice more fluctuation in temp than before. Possibly because it was actually working. You also can't go wrong with the OEM part.

 

[AH64ID]

Go with the 190°, the 180° will not give you any extra wiggle room. Max temp per Cummins is 225° with a 190° and 212° with a 180° thermostat, so you actually lose 3°.

The thermostat is what dictates the max temp based on the ability to reject heat, if you get above 212° with a 180° you are working the motor harder than the cooling system can keep up with.

In addition to the 3° less wiggle room above full open then fan is programmed around a 190° thermostat, and by the time you get 100% fan operatio you will be above the max allowed temp.

While you may never really notice it, the 190° will provide better economy and power than a 180°.

 

[fkovalski]

What is the stock temp thermostat from the factory?

 

[AH64ID]

For your 2005 its 190°.

 

[BIGNASTY]

I replaced my Factory 190 with 180 and have never really noticed any difference.

 

[AH64ID]

I replaced my Factory 190 with 180 and have never really noticed any difference.

I will throw my . 02 in here about that.

A hotter thermostat will generate better fuel economy, it's why they have been increasing the temp over the years. Will you see a change with 10°, maybe not but the 6. 7 guys who go from 200° to 180° are seeing a drop.

But more importantly the ECM is programmed to operate the fan around a 190° thermostat, and when you change the temp you are now not operating in the area you are programed for. The 180° thermostat has a max allowed operating temp (per Cummins, not Dodge) of 212°. The fan is not commanded to 100% until you are above that temp, so your fan is useless or you are operating too hot for the given thermostat.

If it wasn't for the fan I would put a 200° thermostat in my truck.

 

[BIGNASTY]

I will throw my . 02 in here about that.

A hotter thermostat will generate better fuel economy, it's why they have been increasing the temp over the years. Will you see a change with 10°, maybe not but the 6. 7 guys who go from 200° to 180° are seeing a drop.

But more importantly the ECM is programmed to operate the fan around a 190° thermostat, and when you change the temp you are now not operating in the area you are programed for. The 180° thermostat has a max allowed operating temp (per Cummins, not Dodge) of 212°. The fan is not commanded to 100% until you are above that temp, so your fan is useless or you are operating too hot for the given thermostat.

If it wasn't for the fan I would put a 200° thermostat in my truck.

AH64ID
I don't know about that you could be right?? I use to keep strict account of my MPG, and now I just fill when it gets close to the E on the tank, I will say that I have not noticed any big difference in it than when I had the other thermostat. Temp wise this truck has never got close to being hot it runs with the temp gauge needle covering the high side of the 2 on the 200 of the gauge. Pulling a pretty good load and grade coming back from Indy with Daughters things it got to in the middle of the two 0's of the 200 on the gauge, and had my foot stuck in it pretty hard,drop off the downhill side and it falls back to norm running temps.

BIG

 

[Alan Reagan]

I would go with the 190. My truck was in the shop and they ended up replacing three injectors (that wasn't the problem). The mechanic said they were beginning to carbon up because they were being run too cool. The problem was the fan clutch constantly engaging/disengaging and not allowing the temp to get up to 190. If the coolant temperature is decreased, the heat transfer from the cylinder to the coolant is increased and the combustion temperature is decreased. Emissions are increased with the lower combustion temperatures with the current #2 diesel. There are some low temperature diesel studies underway that have determined that there are some low temp diesel fuels available and the emissions are significantly lower that what we have now.