Thermostat opinions - Lower Set point for Summer

[TiGeo]

A 180 deg t-stat will do nothing for this issue here. Does your temp gauge actually move off its normal position? You may have some airflow issues through you radiator...is your condenser beat up/fins in bad shape reducing airflow? System components working as they should? Coolant fresh?

An example of what a lower temp range t-stat is helpful for is buying more time before the system is overloaded during performance driving situations (track etc.) by being "wide open" earlier at a lower temperature vs. allowing higher temps to build before opening fully. Once open a thermostat is doing zero to regulate coolant temps. Disclaimer: this is for a simple cooling system...many modern systems are very complicated and include ECU control of other portions like trans and oil cooling circuits.

 

[clinebarger]

The fan/s being able to regulate temp says it all.....You have no issues besides the factory ECM programming that lets coolant temp run up to 226°/230° before activating the fan/s.

Running the A/C usually helps as the fan/s will react to head pressure.

 

[meep]

Right. That thermostat could full open at 160F, but if you aren’t moving and the fans dont kick in until 224F, there’s no air moving to pull the heat away. Chrysler is not alone in this design - a lot of ecoboost owners who tow in the desert have asked the same question while seeing temperatures they don’t care to see. The fans need to come on sooner at idle to counteract what you are seeing. I personally would not lower the thermostat. I would keep it clean, make sure the antifreeze concentration is correct, and … measure voltage drop between the frame of the alternator and battery ground, and add grounds if needed. Both of mine had something like 1.8V drop or something huge when lights, defrost and both fans were running.

Engine temps fluctuate more than people want to see - and the mfrs put a dead zone in the gauges to reduce owner concern.

What year van? I had a couple of gen 4 town and countries - and really liked them both. Like you, it was amazing how much heat they can put out. I found the transmissions also get hot in those, especially in the summer, especially with the AC on, especially on a hill climb. 225-240 was not out of the question for uphill stints. Those drivetrains manage a lot of power in a very small package.

I think I played with water wetter in one. It did not make a notable difference. But in the end, I never had a problem with either of them from heat, either. I had one with the 3.3 and one with the 3.8, and both were great vehicles. I *did* replace the transmission fluid with amsoil synthetic and felt better about that.

If yours is a gen 4, keep an eye on the wiring harness that comes over the transmission on the driver side and then wraps around and comes sideways across the front. Both of mine started the chafe.

 

[edyvw]

Common trick on track among people who don’t have cooling sorted out for track purposes is to go lower T-Stat temperature. That allows them to buy maybe one or two extra laps. Eventually, they will hit high enough temperature to have CEL and engine dialing back power.
So, first: is there a problem running 224f? My BMW runs in easy, HWY coast mode around 235-240f. But BMW has electric water pump, so it will go in full cooling mode if I push it. Point is, cars can sustain that.
If you think it is an issue, then try to find culprit. If you would like to run cooler, dilute coolant a bit. That will make heat exchange more efficient.
Next step is all aluminum radiator.

 

[Donald]

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 the factory thermostat is the proper one to use. If you have a cooking system problem then it needs to be fixed. Changing the thermostat to a different temp thermostat is not the solution.

 

[eljefino]

Best bet is to get a "pusher" electric fan kit from JC Whitney that has a little probe and relay, and is independent of the computer controlled "relay" which iirc on this van is pulse width modulated for variable speeds.

Your thermostat temp of 190 is fine; it's the no mans land of 35 more degrees before the fan comes on that bugs you.

They usually use logic like this for the CAFE fuel economy run where they know they idle here and there for 75 seconds.

 

[Cruisin'n5thgear]

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.

Sitting in traffic, there is no airflow over the radiator, so without the fans running, the temp will rise. Fan relay temp is the controlling factor here.

 

[Cruisin'n5thgear]

Those who notice cooler stationary temps when changing thermostats likely have engine driven fans, which will continue to move air over the radiator always, even when parked.

 

[MaximumMini]

Thanks. Lot's of helpful advice.

I find it odd that some people with the exact same vehicle (year and model), same type radiator (and not even as new as mine), report they "Never" see temps above 212F? That does not jibe with the Factory service Manual for that particular vehicle as the fans don't even come on until 224F. The case in particular does not admit ANY changes to the factory fan or fan relay system.

I think the consensus here is to adjust the fan relays so that they come on sooner.
Not sure yet how to to that since the BCM controls fan operation. I'll have to study the FSM.

 

[eljefino]

You'd need a tune. And like I wrote, I don't think you have a fan "relay", but rather a controller, a MOSFET, a solid state doohickey.

 

[JHZR2]

What about at 200F? 205F? 210F?
If it doesn't FULLY open until 238F then changing it to open earlier couldn't hurt it seems.

That's what I'm getting at.
That said, the consensus is that it won't make any difference and basically, I believe that to be true

It won’t make a difference, heck, it can’t make a difference at steady state.

What can come into play are cases of subpar thermostats not opening fully. Have you verified that?

 

[tblt44]

35 years ago I used to drill 2 small 1/8 holes in the flange so when it was closed it still slowed slightly.
Did it help couldn't tell.
But in my mind if my thermostat ever stuck closed I would have some water circulating to help prevent overheating

 

[TomYoung]

trick the ecu into thinking it's running hotter than it is. should be easy and cheap, a few resistors at most. Or leave it as is.

This is terrible advice.

 

[50yr Street Mech]

Maybe a bad gauge ? Install one of those after market gauges you can pick up in a speed shop. There cheap and easy to install. That will rule out a bad cluster.

 

[MaximumMini]

Maybe a bad gauge ? Install one of those after market gauges you can pick up in a speed shop. There cheap and easy to install. That will rule out a bad cluster.

Well, it's a new sensor and I'm using OBDII to get the reading.
But I guess anything is still possible. Thanks

 

[MaximumMini]

You'd need a tune. And like I wrote, I don't think you have a fan "relay", but rather a controller, a MOSFET, a solid state doohickey.

I "think" I found the best solution.
An aftermarket, adjustable 160F - 240F fan control system.
That way I can manually set the On/OFF temps that I want.

 

[Jetronic]

This is terrible advice.

if you do it wrong.

 

[factorytuned2012]

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’d leave it alone the car was designed to run and operate with that t-stat.

 

[eljefino]

I "think" I found the best solution.
An aftermarket, adjustable 160F - 240F fan control system.
That way I can manually set the On/OFF temps that I want.

Yeah, this is about what you want, but if the PCM can't see the fan controller it might throw a code which would be a problem if you live in an emissions state. Hence my suggestion for the "pusher" fan with its own independent probe and relay system, which would get installed in front of the condenser, blowing rearward.

 

[ripcord]

Basically, after reading this thread, it sure seems to me that there is nothing wrong with the cooling system of @MaximumMini's van. He merely has a disagreement with the manufacturer about what the appropriate temperature is to turn the fans on and off. Have you tried turning the AC on to force the radiator fans on? If you don't want the cabin cooling from AC, you can also turn up the temperature on the heater to compensate.

The simplest way that I can think of to MacGyver an override of the ECU logic without a custom tune would be to install a small resistor or potentiometer inline on the temperature sensor signal wire. Maybe in the rage of 5 to 25 ohms. I'm guessing you'd want to reduce the voltage in the range of tenths of a volt. The normal theory of operation in most cars is that the voltage returned by the sensor goes down as the temperature goes up, so pulling the voltage lower with a resistor will trick the ECU into seeing a higher coolant temp and turn the fans on and off at a cooler temp. You would probably want to put this resistor on a manual switch for hot days as it would also have the effect of causing the ECU to keep it in open loop longer during warm up and running slightly richer at times.

This idea only works, BTW, if the sensor is a conventional that returns a voltage based signal.