Thermostat opinions - Lower Set point for Summer

[MaximumMini]

Got a Dodge minivan.
Factory Thermostat = 195F
Current thermostat = 195F
Runs a bit warm in the Summer only when sitting still on very hot days in traffic or at long red lights etc.
When moving it seems to do fine.

Sitting still in traffic Max temp = 224F-228F (fans kick on, temp drops back to 212F, then rises again...repeat)
Moving = 197F-205F

228F seems too close to 260F (purely opinion) and I'd like to see it hover a bit lower when sitting in traffic etc.
But installing a thermostat will probably give me temps under the 195F specified for this engine when moving. (If radiator has the capacity)
Would installing a 180F - 190F thermostat help (or hurt)?

 

[alcyon]

Got a Dodge minivan.
Factory Thermostat = 195F
Current thermostat = 195F
Runs a bit warm in the Summer only when sitting still on very hot days in traffic or at long red lights etc.
When moving it seems to do fine.

Sitting still in traffic Max temp = 224F-228F (fans kick on, temp drops back to 212F, then rises again...repeat)
Moving = 197F-205F

228F seems too close to 260F (purely opinion) and I'd like to see it hover a bit lower when sitting in traffic etc.
But installing a thermostat will probably give me temps under the 195F specified for this engine when moving. (If radiator has the capacity)
Would installing a 180F - 190F thermostat help (or hurt)?

I think a 180F is a great all rounder, but you will have to monitor if on colder days is it not warming up correctly. For instance, I installed a beck arnley 170F stat in my car that originally uses a 180F stat. What happened was it seemed to be opening way earlier than 170F and it is very noticable on colder rainy days , and lowering the operating temp too much. I think its more of a stat quality issue. Stay with a good quality stat if possible OEM one and observe.

 

[Lubener]

I have found when I installed a cooler thermostat in a vehicle which ran too warm that eventually the temperature crept up to the same temperature as before. It just took longer to get there. If you think your engine is going to run 10-15 degrees cooler, don't count on it. The cooler thermostat was not the long term solution.

I would try to find out why your Dodge is running too warm. My bet is the radiator is not in the greatest shape. The fins on the radiator or condensor are partially blocked , reducing air flow or the fan is not energizing at the proper temperature. I would believe the fan should be turning on sooner than what you mentioned..

 

[SubieRubyRoo]

Have you done a cooling system purge with either a factory-installed bleeder (I don’t know if your minivan has one) or a Lisle radiator funnel? You could have air pockets near the temp sensor and are getting a false reading.

 

[billt460]

I switched the thermostat in my truck from a 190 to a 180 years ago, and never looked back. It runs noticeably cooler on the temperature gauge.

 

[rstcso]

If you think your engine is going to run 10-15 degrees cooler, don't count on it. The cooler thermostat was not the long term solution.

I would try to find out why your Dodge is running too warm. My bet is the radiator is not in the greatest shape.

This ^^^. I had a 1999 Dodge conversion van with the 318 engine having similar issues. Bought it new, so knew how it was maintained. Went through flushing, changing thermostat, etc. Finally replaced the radiator and all was well. Sold it to my next door neighbor and he passed it on to a large family in need. Still running good to this day.

 

[John105]

My thoughts are something isn't right, but maybe replace the thermostat with the correct one? And if it still runs hot, potentially the radiator isn't doing its job?

One of our cars does not have a temp gauge, but the others have always had the needle in the same spot, and one is a 2007 and the other was a 2011, and 1998. Someone else out there knows for sure, but for the temp gauge to always be the same, even when it's 95F or 105F, doesn't this mean that the thermostat has to be closed to some extent? In other words we cannot simply remove a thermostat altogether in the summer, and expect the temp to be the same as if it were in place?

I don't know what a thermostat looks like in a modern car, because on our 2011 it was a housing, not a small device that drops in. But temp is something that's important, especially if running hotter than normal. So I'd want to know the thermostat is 100%, before going further, and I'd use the correct one... my .02

 

[SC Maintenance]

Modern thermostats - maybe always?? - aren't that simple. My Fronty is full open at 180, and closed at 171. So there is kind of a range. I have also noticed that range on aftermarket stats often isnt that precise.

I am thinking something else isn't working - like the rad is plugged with bugs, or the aux fan is not kicking in soon enough or is weak?

If you do change the stat, I would start by going to an actual OEM part first - see if that helps.

 

[Mechanician]

Because the temp only rises that high while setting still, it appears that's the temperature the fan switch is set to.
Not the thermostat. Why are the fans cycling, don't you use the A/C?

 

[Kira]

Year, make, model, engine, odometer reading and a mention of the overall condition of the cooling system would be interesting.

 

[kschachn]

Changing the thermostat won't change what you're seeing.

 

[football]

Is it the 3.6L? I had a 2017 Chrysler minivan with that engine that would get very hot in traffic if I had the AC off. Turning the AC on would turn the fans on and keep them on but if I turned the AC off, I never heard the fans. Don’t know if the fans ever came on at higher temp. Don’t know if there was something wrong with the relays or what. Maybe it was operating as designed. But I wasn’t comfortable watching the needle creep up. So… I just made sure to keep the AC on (and thus, the engine cooling fans) especially when at stoplights or in traffic.

 

[MaximumMini]

I have found when I installed a cooler thermostat in a vehicle which ran too warm that eventually the temperature crept up to the same temperature as before. It just took longer to get there. If you think your engine is going to run 10-15 degrees cooler, don't count on it. The cooler thermostat was not the long term solution.

I would try to find out why your Dodge is running too warm. My bet is the radiator is not in the greatest shape. The fins on the radiator or condensor are partially blocked , reducing air flow or the fan is not energizing at the proper temperature. I would believe the fan should be turning on sooner than what you mentioned..

Thanks football.
In this case, the vehicle has a new radiator and the condenser and radiator were carefully cleaned recently.
Also, the coolant is fresh and there is no sign of any sludge or contamination in the cooling system. It is maintained with great care.

As far as the fans, the fan relay was replaced and the fans come on (and turn off) at exactly where the Factory Service Manual says they should. I think these particular minivans might simply have slightly undersized radiators.

 

[Nick1994]

An open thermostat is an open thermostat.

My Jeep didn’t run any cooler in the summer with a 180* than it does with a 195*. We don’t have extreme winters here but it still gets chilly, and it ran too cool and the heater was weak. Swapped a 195* back in and nice heat.

 

[MaximumMini]

My thoughts are something isn't right, but maybe replace the thermostat with the correct one? And if it still runs hot, potentially the radiator isn't doing its job?

One of our cars does not have a temp gauge, but the others have always had the needle in the same spot, and one is a 2007 and the other was a 2011, and 1998. Someone else out there knows for sure, but for the temp gauge to always be the same, even when it's 95F or 105F, doesn't this mean that the thermostat has to be closed to some extent? In other words we cannot simply remove a thermostat altogether in the summer, and expect the temp to be the same as if it were in place?

I don't know what a thermostat looks like in a modern car, because on our 2011 it was a housing, not a small device that drops in. But temp is something that's important, especially if running hotter than normal. So I'd want to know the thermostat is 100%, before going further, and I'd use the correct one... my .02

It's not running "hot" according to the factory service manual.
In fact, it runs about exactly where the factory service manual says. But the factory service manual calls for fans to kick on LOW MODE at 224F and to me that just feels too hot.

And I have several of this exact same vehicle. Both maintained like aircraft.
They both run about the same temperature in the Summer

 

[Chris142]

The thermostat only controls the minimum temp. If the cooling system can only maintain 240f on a hot day putting in a thermostat with a lower opening temp won't make any difference.

 

[MaximumMini]

Because the temp only rises that high while setting still, it appears that's the temperature the fan switch is set to.
Not the thermostat. Why are the fans cycling, don't you use the A/C?

The fans are cycling exactly as prescribed in the factory service manual. I try it with and without AC. it does run a bit cooler with the AC off....or more correctly I should say.....it takes longer for the fans to cycle when the AC is off.

it has a new AC pressure switch, New thermostat, new radiator, good compression, not losing any coolant, fresh radiator flush with a 15% antifreeze / 10% Rislone Hyper Cool / 75% water mix for coolant. Clean and clear as can bee with no contaminants in the coolant.

 

[MaximumMini]

Is it the 3.6L? I had a 2017 Chrysler minivan with that engine that would get very hot in traffic if I had the AC off. Turning the AC on would turn the fans on and keep them on but if I turned the AC off, I never heard the fans. Don’t know if the fans ever came on at higher temp. Don’t know if there was something wrong with the relays or what. Maybe it was operating as designed. But I wasn’t comfortable watching the needle creep up. So… I just made sure to keep the AC on (and thus, the engine cooling fans) especially when at stoplights or in traffic.

One is a 3.3L and the other a 3.8L. Both Gen3, 1999

 

[Chris142]

But the factory service manual calls for fans to kick on LOW MODE at 224F and to me that just feels too hot.

Just because your body does not want to be 224F does not mean your engine does not like it. 224 is perfectly acceptable for it.

 

[MaximumMini]

An open thermostat is an open thermostat.

My Jeep didn’t run any cooler in the summer with a 180* than it does with a 195*. We don’t have extreme winters here but it still gets chilly, and it ran too cool and the heater was weak. Swapped a 195* back in and nice heat.

I read that most thermostats open PARTIALLY at their set temperature and won't FULLY open until 10F - 15F higher than the set temp.
I figured if that was the case, going to a lower set point would also lower the temp at which it is fully open?